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Dynamos and Electric Motors: How to Make and - Forgotten Books

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HANDICRAFT
SF
OF
UNIVERSITY
AT
MAY
GIFT
OF
MORRISON
TREAT
IN
ALEXANDER
CALIFORNIA
ANGELES
LOS
THE
PI FS.
OF
MEMORY
F
MORRISON
Cranl
tion G,
DAVID
McKAY,
1022
Publisher,
Market
Street,Philadelphia.
HANDICRAFT
SERIES
(continued}.
and
Heat
Abrasion.
With
by
Working
Engravings
300
Diagrams.
Contents.
Appliancesused in Glass Blowing. Manipulating Glass Tubing.
JointingTubes to Bulbs forming Thistle Funnels,
Blowing Bulbs and Flasks.
etc.
Blowing and Etching Glass Fancy Articles ; Embossing and Gilding Flat
Glass Apparatus ; Boring Holes in, and Riveting
Broken
Surfaces.
Utilising
Glass.
Hand-working of Telescope Specula. Turning, Chipping,and Grinding
Glass
and
"
G
Manufacture
The
ass.
Model
of Glass.
Boats.
With 168 Engravings and Diagrams.
Yachts.
Building Model
Yachts.
Rigging and Sailing Model
FittingSimple Model Boats.
Building a Model Atlantic Liner.
Vertical Engine for a Model
Launch
Model
Launch.
Engine with Reversing
Gear.
Making a Show Case for a Model Boat.
Electric
to
Make
Fit
Them.
and
With
Bells, How
162 Engravings and Diagrams.
Building
Contents.Making and
The
Contents.
Electr c Current
the Laws
and
used in Electric-Bell Work.
Conductors
Wiring for
Batteries for
Systems of Wiring ; Burglar Alarms.
of Electric Bells,Pushes, and Switches.
"
that Govern
it. Current
Electric Bells. Elaborated
Electric Bells.
The Construction
Indicators for Electric-Bell
Systems.
With
Work.
177 Engravings and Diagrams.
How
Contents."
Bamboo
and Uses.
Bamboo.
to Work
: Its Sources
Bamboo
Bamboo
Bedroom
Tables.
Chairs and Seats. Bamboo
Furniture.
Bamboo
Bamboo
Music
Hall Racks and Stands.
Bamboo
Racks.
Cabinets and Bookcases.
Bambco
Window
Blinds. Miscellaneous
Articles of Bamboo.
Bamboo
Bamboo
Mail
Cart.
With
108 Engravings and Diagrams.
Contents."
Skinning Birds. Stuffing and Mounting Birds. Skinning and
Heads
: Polishingand
ing
MountStuffingMammals.
Mounting Animals' Horned
Horns.
Skinning,Stuffing,and Casting Kish. P. eserving,Cleaning,and
Dyeing Skins.
Preserving Insects,and Birds' Eggs. Cases for Mounting
Taxidermy.
Specimens.
Engravings and Diagrams.
Methods
of Stitching. Simple Repairs
and
and
to Cut
Pressing. Relining,Repocketing, and Recollaring. How
Make
Vests.
How
Make Trousers.
to Cut and
Cutting and Making Lounge
and Reefer Jackets. Cutting and Making Morning and Frock Coats.
and
Accessories.
Cameras
TO
Comprising How
Photographic
Tailoring;.
Contents."
With
180
Tailors' Requisitesand
and
STANDS.
DARK
160
With
MAKE
SLICES, SHUTTERS,
CAMERAS,
Illustrations.
Contents.
PhotographicLenses and How to Test them. Modern Half-plate
Cameras.
and
Pocket
Cameras.
Hand
Ferrotype Cameras.
Stereoscopic
Dark
Slides.
Cameras.
Cameras.
Cinematograph Management.
Enlarging
"
Optical
Comprising THE
Lanterns.
OPTICAL
LANTERNS
CONSTRUCTION
MAKING
MANAGEMENT
AND
SLIDES.
With
160
Illustrations.
lanterns.
Illuminant
Contents."
for
Dissolving View
Single Lanterns.
Accessories.
Lantern
Lanterns.
Conducting a Limelight
Optical
Optical
Lantern
Exhibition.
Painting Lantern
Experimentswith Optical Lanterns.
Slides. Mechanical
Lantern Slides. Cinematograph
Slides. Photographic Lantern
OF
AND
THE
OF
Management.
Engraving
Contents.
"
With Numerous
Illustrations.
Metals.
used.
Introduction and Terms
Engravers' Tools
and
their Uses.
Elementary Exercises in Engraving. Engraving Plate and Precious Metals.
Engraving
Engraving Monograms. Transfer Processes of Engraving Metals.
Name
Plates.
Engraving Coffin Plates. Engraving Steel Plates. Chasing
and
Embossing Metals.
Etching Metals.
With
189 Illustrations.
and Materials.
Simple Baskets. Grocer's Square Baskets.
Wicker
Round
Elbow
Chairs.
Flat Fruit Baskets.
Baskets.
Oval Baskets.
Basket Bottle-casings.Doctors' and Chemists' Baskets.
Fancy Basket Work.
Sussex Trug Basket.
Index
Miscellaneous Basket Work.
Basket
Work.
Contents."
Tools
DAVID
McKAY,
Publisher,1022
Market
Street, Philadelphia.
HANDICRAFT
Bookbinding.
SERIES
(continued}.
With
125 Engravings and Diagrams.
Printed Book
Book Sheets.
ing
Beatsheets.
ing
BeatAppliances.
Appliances,
FoldingPrinted
folding
and Sewing. Rounding, Backing,and Cover Cutting. CuttingBook Edges.
Cloth-bound
Cloth-bound
Account
Book
Covering Books.
Books, Pamphlets, etc.
Books,
and
Ledgers, etc. Coloring,Sprinkling,
Marbling Book Edges. Marbling
Book
Papers. Gilding Book Edges.
Sprinklingand Tree Marbling Book
Covers.
Lettering,
Gilding,and FinishingBook Covers. Index.
Contents.
Contents.
Bent
Bookbinders'
uookDinders
"
Iron
Work.
IncludingELEMENTARY
ART
METAL
WORK.
With
269 Engravings and Diagrams.
Contents." Tools and Materials. Bending and Working StripIron. Simple
Exercises in Bent Iron.
Floral Ornaments
for Bent Iron Work.
Candlesticks.
Hall Lanterns.
Screens,Grilles,etc. Table Lamps. Suspended Lamps and
Flower
Bowls.
Floor
Photograph Frames.
Newspaper Rack.
Lamps.
Miscellaneous
Examples. Index.
With Numerous
Engravingsand Diagrams.
Ihe
and
its Accessories.
Camera
The
Contents
Studio and the Dark
Plates.
Room.
tion
Exposure. Developing and Fixing Negatives. Intensificaof Negatives. Portraiture
and
Reduction
and
Picture Composition.
Photography. Retouching Negatives. Processes of Printingfrom
Flash-light
scopic
Negative*. Mounting and FinishingPrints. Copying and Enlarging. Stereo-
Photography.
"
Photography. FerrotypePhotography.
in Preparation.
Other
Volumes
TECHNICAL
Series of Practical Volumes.
ImportantNew
N.
With
HASLUCK.
book
Each
INSTRUCTION.
contains
about
1
Edited
by
PAUL
Illustrations in the Text.
numerous
60
pages,
crown
8vo.
Cloth,
$I.oo each, postpaid.
Practical
Draughtsmen's
With 226 illustrations.
Work.
ments.
.-DrawingBoards. Paper and Mounting. Draughtsmen's InstruCurves.
Drawing StraightLines. Drawing Circular Lines. Elliptical
Projection.Back Lining Drawings. Scale Drawings and Maps. Colouring
Drawings. Making a Drawing. Index.
Practical
Gasfitting. With 120 Illustrations.
Contents.
How
Coal Gas from the Retort to the Gas
Coal Gas is Made.
Gas Supply from Gas Holder to Meter.
Laying the Gas Pipe in the
House.
Gas Burners.
Incandescent Lights. Gas Fittings in
Gas Meters.
for Festival Illuminations.
Gas Fires
Gas Fittings
Workshops and Theatres.
Contents."
Holder.
and
Index.
Cooking Stoves.
Practical
Staircase
Joinery.
With 215 illustrations.
.Contents.
Introduction : Explanationof Terms.
Simple Form of Staircase
"Housed
Two-flight
String Stair : Measuring, Planning,and SettingOut.
Staircase with Winders
Staircase.
Staircase with Winders
at Top
at Bottom.
Staircase over
an
and Bottom.
Staircase with Half-spaceof Winders.
Oblique
Plan. Staircase with Open or Cut Strings. Cut StringStaircase with Brackets.
Open StringStaircase with Bull nose Step. Geometrical Staircases. Winding
Staircases.
Ships'Staircases. Index.
"
With 247 Illustrations.
Metal
Plate Work.
Contents." Materials used in Metal Plate Work.
Geometrical Construction
of Plane
Figures. Geometrical Construction and Development of Solid
Soldering and
Figures. Tools and Appliances used in Metal Plate Work.
Brazing. Tinning. Re-tinning and Galvanising. Examples of Practical
Metal Plate Work.
Examples of Practical Pattern Drawing. Index.
Practical
Practical
Graining and
Marbling. With 79 illustrations.
Contents." Graining: Introduction,
Aids.
Tools, and Mechanical
Graining
Oak
Grounds and GrainingColors.
Grainingin Oil. Oak Graining in Spirit
Oak Graining. Maple Graining
Colours.
Pollard Oak and Knotted
and Pitch-pineGraining. Walnut
ing.
GrainGraining. Fancy Wood
Furniture
by Staining. ImitatingInlaid
Graining. ImitatingWoods
Woods.
Marbling: Introduction,
Tools, and Materials.
ImitatingVarieties
of Marble.
Index.
and Water
Mahogany
Ready Shortly: Practical
Other
DAVID
New
McKAY,
Volumes
1022
Publisher,
Work.
Plumbing
Preparation.
Market
Philadelphia.
Street,
in
"
WORK"
DYNAMOS
HANDBOOKS.
AND
ELECTRIC
MOTORS
THE
A.F.
MEMORIAL
LIBRARY
ELECTRIC
AND
DYNAMOS
MOTORS
HOW
WITH
TO
MAKE
NUMEROUS
AND
RUN
ENGRAVINGS
AND
EDITED
N.
PAUL
THEM
DIAGRAMS
BY
HASLUCK
""
OF
EDITOR
AUTHOR
OF
"
"WORK"
AND
HAKDYBOOKS
"BUILDING
FOR
WORLD,"
HANDICRAFTS,"
ETC.
PHILADELPHIA
DAVID
McKAY,
1022, MARKET
1903
PUBLISHER
SJREET
ETC.
PREFACE.
THIS
Handbook
everyday
Electric
of
edit"
g=
principlesof
and
of
Run
the
much
that
g
jected.
"
anew,
altered
Z
causes
the
and
largely
contributions
writings of
it is my
book
columns
the
form
volumes
character
to
general
to
are
WORK,
to
be
mass
be
re-
arranged
From
these
blended
so
be
cannot
the
of
had
re-written.
of many
individuals
and
fortune
on
necessarilyhad
remainder
tion
informa-
it treats.
in the
tautologicalin
was
The
which
contained
matter
the
for
Dynamos
information
publicationin
for
of
thousand
ten
weekly journals
subjects on
preparing
C
convenient
Small
over
supplies concise
relevant
the
and
scattered
of the
one
K
In
Make
to
Motors,
WORK,
form
a
comprehensive digest
a
use,
How
on
""
contains, in
that
distinguishedfor
acknowledgment.
who
Readers
special
should
be
details
Handbook,
this
address
answered
I.'t Belle
of
additional
the
question
the
columns
Saw".ioe, London.
434360
to
information
dealt
matters
instruction
or
a
in
desire
may
kindred
on
WORK,
of
that
P.
N.
so
with
in
subjects,
that
journal.
HASLUCK.
specting
re-
it may
CONTENTS.
CHAP.
PAGfi
I.
Introduction
9
"
......
II.
Siemens
The
Dynamo
"
.21
.
.
III."
The
Dynamo
Gramme
.41
.
.
IV."
Manchester
The
.
.
Dynamo
61
....
The
V."
Simplex
Dynamo
66
....
VI."
Wire
Size
the
Calculating
Small
for
and
Amount
of
Dynamos
76
...
VII.
Ailments
of
Dynamo-Electric
Small
"
Machines
:
their
Causes
Cures
and
89
.
VIII."
Electric
Small
without
Motors
Castings
98
.
IX.
How
Determine
to
Direction
the
of
"
Rotation
of
a
Motor
.112
.
X."
XI."
How
to
Fifty-
Watt
Make
a
Shuttle-
Undertype
.
.
Motor
Armature
Dynamo
119
.129
.
XII."
Watt
Four-Hundred-and-Forty
Type
Manchester
Dynamo
144
.
,
LIST
OF
ILLUSTRATIONS.
LIST
ILLUSTRATIONS.
OF
ing
wind-
Dynamo.showing
Field
of
101." Bearing Brackets
102." Bobbin
for Magnet
Manchester
of
66." Section
103."
Magnet
62
Cores
.
.
.
for
Core
91." Magnet
chester
Man-
Dynamo
Iron
71.
Clamp
72." Method
"
winding
of
"
68
68
111, 112."
113, 114."
115, 116.
69
117."
70
118."
Ring
...
for
Plug
Wooden
67
of Simplex
74." Commutator
Dynamo
75.
"
...
Simplex
complete
of
Armature
Dynamo
.
...
Dynamo
73
73
74
...
80.
Bearings of Armature
81." Brush-Holder
82.
Dynamo
Simplex
"
.
88."
89."
Plan
...
Gun-metal
.
.
.
.
Magnet
and
Front
Limit
and
121."
Gun
.
Armature
"
.
.
for
Holders.
Brush
123
....
....
.
99
101
102
.
.
129
winding
-Holders,
...
and
Rocker,
complete
131."
132."
Plan
Brushes
Side
of Dynamo
of ditto
View
102
128
132
.
.
and
133
Motor
....
View
of ditto
133." End
of Armature
Side View
13K"
of Armature
135.-End
View
136." Field
showing
Magnets
of Winding
Method
of Commutator.
Position
137.
of Manchester
138." Plan
namo
Dy.
136
.
138
.
103
104
.
138
141
.
"
...
.
.
...
102
.
123
124
Brush-Holder
complete.
with
Milled
Screw
Brass
124
Head
.124
127." Brush
125
128." Commutator
ing
of Motor, show129." Section
.
f-in.
....
.122
125."
126."
100
showing
-
.
.
Castingfor Brush-Holder
Head
124.-Casting for Milled
Screw
121
for
.122
Motor
130,-Brush
of ditto.
.
.
Foot
metal
-
...
of Commutator
Shaft complete
ing
of Brass BearView
95." End
for Armature
Shaft
of Miniature
View
96." End
with
Electric
Motor
Iron Yoke
of ditto
Elevation
97._Side
of Small
98." Side Elevation
with
Horse-shoe
Motor
Wooden
and
Magnet
Saddle
....
of ditto
Elevation
99." End
VOO." Plan of ditto
Face
94.
86
87
Magnet
Shape of Brush
93."
Ends
Armature
85
.
Block
of
Field
Block
Elevation
90."
91." Armature,
92."
85
120
for
Casting
123."
-
...
86."
87."
.119
.
121
120."
74
.
117
....
.
....
84."
85."
.
.
Motor
.
122." Rocker
plete
com-
Shuttle
of
Section
Armature
of ditto
Side View
of
Section
Cog
ring
Armature
of ditto
Side View
Electric
Motor
Simple
.98
I
complete
of Field
Elevation
Side
83."
.
with
Field
Casting
Magnet
Armature
for Shuttle
Motor
for
119." Armature
Casting
tor
MoShuttle-Armature
...
"
116
.
-
71
72
72
72
.
Piece of ditto
76.-Pul"
for Magnet of ditto
77." Yoke
78." Coil Flange
of
Simplex
79." Bed-Plate
.
.
Motors
Shunt
driven
Motors
Two
Batteries
Shuttle- Armature
complete
.113
.114
.
"
ture
Arma-
....
Bar
in
.
Motors
Series
110
.
Magnetism
Magnets
.
110
.
Breaker
rents
Curof
Resultant
and
.
Simplex
Core
Armature
Core
for Armature
.
Armature
107-110." Directions
.
.
.
.
wheel
and Contact
-
63
Flanges
for making
Armature
73.
63
109
110
.110
Breaker.
.
108
Contact
.
Fly
Coils
.
-
106."
.
.
Magnet.
Horse-shoe
104." Iron Armature
105." Setting
out
63
.
Core with Fillets
68." Magnet
to receive Flanges
Core fitted with
69." Magnet
70." Former
PAflE
FIO.
PAGE
HO.
.
14i
of ditto
View
147
139." End
of
Section
140." Longitudinal
.148
ditto
thod
141." End
View, showing meature
of winding Arm107,
and
107
Fields
151
152
108
142." Brush
Gear
.
106
106
.
.
.
142
.
.
.
.
.
.
.
.
.
.
DYNAMOS
ELECTRIC
"
MOTORS.
CHAPTER
I.
INTRODUCTION.
the
SINCE
invention
Pixii,the
machine
evolution.
It
electric
steel
It
acted
as
then
required
when
name
truly
as
the
bear
to
were
because
of its successors,
the
continued
magnets
was
first
under
began
and
the
dynamo
passed through many
has
machine,
permanent
of
of
this
1832, by
phases
whilst
name
in
its
dynamo
as
any
a
magnets
It is not
of
magneto-
a
employed
permanent
moved.
in
intended
struction.
conone
only
in
history of the machine, but
how
small examples of those which
to make
to show
are
for electric lightingpurposes.
in general use
These
now
be arranged in classes named
according to the
may
this
types
Handbook
of
to
give
armatures,
a
of
the
either
the
or
field magnets
used
in
their construction.
Before
describing
dynamo
its
action,it
would
be as well to consider
when
and why the dynamois used, instead of primary batteries,
electric machine
as
of generating electricity
for lightinglamps, etc.
a means
In the first place,the lighting of electric lamps by the
of primary batteries
is only practicableunder
agency
somewhat
restricted
conditions.
To get a sufficiently
have
force
it is necessary
to
a
high electro motive
in series,
and big cells
of cells connected
great number
are
required to provide the current, or the battery will
down.
When
soon
run
a cell is required to give a current
of three
it polarises very
rapidly ;
or
amperes
more,
hence
of the lamp circuit (as by
the resistance
to lower
or
DYNAMOS
io
ELECTRIC
AND
MOTORS.
4s costlyand inconvenient,
placingthe lamps in.parallel)
is thus thrown
the
greater-demand ^fbr current
on
and laborious job of
battery. Then the costly,
.dirty,
cleaning]and tGcliarglhgthe Tells- is enough to make
as
a
.
wish
one
for
better
some
method
of
generatingthe
electric current.
Small
electric lights,
such
of
lights
low candle power,
two-cell chromic acid battery,
or
battery. But
when
the
and
night-lights
as
a
even
of
area
be fed with
may
sional
occaa
small
Fuller bichromate
lightingis extended,a
This is a
dynamo-electricmachine is generallyused.
machine
for convertingmechanical
into electric
energy
energy.
There
who
many
from
flows,
or
runs,
the
are
other, in
connected
believe that
end
one
certain
a
of
electricity
actually
wire
a
or
when
direction,
conductor
the
ends
to
are
batteryor dynamo. For instance,in
of a batteryof primary cells,
is
the case
the current
always spoken of as coming from the carbon terminal,
and returningto the
going through the external circuit,
is misleading; for the expreszinc. This,in pointof fact,
sion
and it might easilyhave been
is quiteconventional,
to
a
expressed the other
came
electricity
to
be studied
in the science,it was
the phenomenon in this way.
a
a
similar
have
it was
manner
or
and
made
no
laws.
But
advance
mutually agreed to
made
In
would
to electrical formulae
difference whatever
when
and
way,
agreed to call
one
was
express
end
of
magnet the north pole,and
in this
case
It is this
we
are
along been giving our
else Franklin,and many
or
magnet ends wrong
names,
been searching the
others after him, have diligently
Arctic
all the
:
the
we
time ; for like
are
have
for the North
Seas
all
Pole
when
poles repel each
it is the south
other, unlike
noticed that many
careful in callingthe two ends of a magnet
polesattract
writers
either
brought
the other the south ; but
face to face with a paradox.
Perhaps it
has been
north-seekingand south-seekingpolesrespectively.
But as regards an electric current, this conventional
INTRODUCTION.
of
way
expressing
is
Electricity
is
water
a
must
useful substance
example when
studying
taken
through
pipe. Although
to make
of
some
use
the
two
of
at
ways
gravity; also,it
an
as
of
in many
ways
not influenced
"
force
of
phenomena
is unlike water
electricity,
yet electricity
it can
be said to work uphill; it is
by the
literally.
flow
not
a
as
very
be
not
liquid; it does
water
through a
not
certain wire
a
it
1 1
be
can
said to act
once.
Whatever
clear
be, it is perfectly
electricity
may
of electrical energy
the present time that sources
different effects upon different substances,
copper,
and other metals
at
have
silver,
this influence.
to
beingvery susceptible
Hence, these metals are called the best conductors.
and
most
But
pound
comglass, vulcanite,paraffinwax,
substances
are
considered,in one
sense, bad
conductors"
traverse
to be
its
flows from
a
"condition"
both ways
As far
back
other,but it is a
entire length; and
circuit or
be
a
"say,
flow
to
"condition"
this
within
this
placed the
batteryor
means
a
and
round
; but
circuit is
that
closed,
wire.
or
electric circuit
from
set
one
up
length must
end
nothing
to
the
throughout the
form a complete
little.
Also,
forming part of it,
matters
and
circuit,
of
stated
right
source
the
ring,the shape of which
somewhere
must
when
alongthe conductor
as
we
know, in an
said
that
to
to
electricity
second ; but it must
this that the current
direction
one
up,
is often
a
from
again
is set
actually be
can
in
source
circuit and
the
fraction of
some
of
current
a
of wire
be understood
account
no
it takes
given length
a
put down
non-conductors.
say
actual time
The
on
some
settingup this "condition"
dynamo.
The
some
Two
followingoutlines represent the field magnets of
dynamos in general use : Undertype, Fig. 1 :
vertical cores
of rectangularsection joined to the
"
cast
pole-pieces,
with
armature
Similar machines
have
cores
Fig.2
:
Two
tunnel
in lower
of circular section.
vertical cores
part
type,
Over-
of suitable section cast
DYNAMOS
yoke
with
at
Coils
part.
base, and the
may
be
MOTORS.
tunnel
armature
wound
Several
cores.
over
ELECTRIC
AND
in upper
then
separately,
modifications
of
this
slipped
machine
designed. Some of these have round cores.
of circular
Single coil or simplex,Fig. 3 : One core
with the armature
section joined to suitable pole-pieces
have
been
tunnel
at the side.
In
one
this machine
form
it?
has
singlecore spanning horizontallythe two vertical poletunnel in the upper
pieces,with the armature
part
of circular section
cores
Manchester, Fig. 4 : Two
bedded
into
two
pole-pieces.Armature
horizontal
part of the machine
tunnel in the central
between
the
Fig. 1." Uudertype Field
Fig. 2." Overtype Field
Magnet.
Magnet.
Fig. 5 : Four horizontal cores of
in the
circular section bedding into massive pole-pieces
of the machine, and into vertical standards at
centre
two
cores.
Gramme
the sides ; armature
,
tunnel in centre
of the machine.
field magnets of these machines
of steel permanentlymagnetised,but
The
up
of
are
not
made
constructed
are
comparativelysoft iron, containingresidual magnetism,
which, by dynamic energy imparted to the
armature, is induced
and
coils,
create
to exert
in them
its influence
on
the
electric current.
an
ture
arma-
This
the field
current, or part of it,is then sent around
with the result that a stronger magnetism
magnet coils,
of the field magnets. Being
is induced in the cores
thus
they
strengthened,
force in the armature
power
of the machine
induce
a
coils,and
is worked
up
higher electro-motive
thus
the full electric
INTRODUCTION.
Now
is measured.
is the
The
Ampbre.
learned
in which
to the way
as
a
unit of current
idea
Some
of
by comparison with other units of measurement.
For instance,in trades where the foot rule is
used, the foot
length. Where
inch
and
units of measurement
are
engines are
steam
pounds
per
Bteam;
and
of
a
inch
square
motive
or
power,
"
in
Where
Field
the
nor
The
acts
measure
on
when
a
is used
as
a
Magnet.
by
cubic
inches,
to invent
the units
a
or
new
can
set
divisions
them.
Ampere
obtained
Field
spring-pressure
gauge
used, so electricians have had
and new
for
of instruments,
names
on
of
electrical measurements,
be
marked
Manchester
water
its volume
gallons.In dealing with
neither the foot rule
speak
we
estimatingthe pressure of
unit in estimatingthe
a
Gramme
speak of
we
4."
of
Magnet.
horse-poweras
steam
engine.
Fig. 5.
used,
Fig.
plex
Fig. ,3." Single Coil or SimField Magnet.
power
of
electricity
generallyaccepted
its meaning may
be
current
is defined
an
as
that
electro-motive
resistance of
one
of electro-motive
Ohm.
force
current
force
A
of
which
one
is
Volt
volt is the unit
roughly as given by
the
I NT
inventors
are
ROD
UC
of machines.
TION.
The
1
armatures
5
generally
are
furnished with iron cores, around which insulated copper
wires are wound.
Machines have been constructed without
iron cores,
and
or
by Messrs.
Thompson. In some
zigzagband of copper
Siemens, Ferranti, Mordey
of those machines
a
looped
has been
attached
Pacinotti
Armature.
four types
on
a
Kelvin
spindle,and
the
"
Fig. 9." Double
Walker
H-girderArmature.
a
into
:
Shuttle
Armature.
armatures, in which the coils are
ring whose principalaxis of symmetry
(1)Ring
upon
ture.
arma-
divided
are
or
Armature.
forms
all armatures
Fig. 8." Shuttle
or
brass
a
Fig. 7." Cogged Ring
Fig. 6." Plain Ring
spider,mounted
By Lord
to
or
grouped
is also
its axis of rotation.
in which
armatures,
(2) Drum
the surface of a
over
longitudinally
the coils
drum
or
(3) Pole armatures, having coils wound
from
radially
polesprojecting
(4) Disc armatures,
againsta disc.
a
in which
disc
or
are
wound
cylinder.
on
separate
central hub.
the coils
are
flattened
DYNAMOS
16
ELECTRIC
AND
MOTORS.
Of these itis as well to say that earlyexamples of the
first type
furnished
were
by
Schuckert, Giilcher, and
second
type
are
to be
Edison, Weston, and
Examples
dynamos
of the
of
useful
few
of
Gramme,
Brush.
Examples of the
found in the Siemens (Alteneck),
Vincent
machines.
Elphinstone-
third
Elmore
type
and
examples
the machines
of
be
to
were
Lontin.
the
There
fourth
in the
seen
but
are
type, except the
Desrosier.
When
eddy
solid iron is
currents
armature
set
are
employed
up
Fig. 10."
Laminated
to become
hot.
for
an
armature
in the iron, and
Shuttle
core,
the
cause
Armature.
Iron armatures
should
fore
there-
be built up of thin sheet-iron discs,
of hoop
or plates
iron,each layerof iron being magneticallyinsulated
from
its
armature
neighbourby
coils should
insulated with
as
varnished
short and
silk
thick
be
at
an
pure
cotton, and
as
is consistent with
excessive
force
calico.
or
copper
or
requisiteelectro-motive
machine
of
paper
wire, well
the wires should
without
be
obtainingthe
driving the
speed.
in
Figs.6 to 9 show the types of armatures
small dynamos and electric motors.
Fig.6 shows
It is
The
formed
generally
of
use
a
for
plain
collars
ringsor
of very thin sheet iron. These may be strung together
attached to the arms
of brass spiders
on
gun -metal bolts,
shown
as
spindle
by the dotted lines,the armature
going through the hole in the centre. The rings are
with
several coils of wire, passing through
\Tound
ring armature.
fXTRODUCTIOff,
the
drum
rings. They
by winding the coils
drum
armature
and
over
rings.Fig.7
This
spiders.Small
armatures
soft malleable iron.
The
sixteen,and
six to
by
The
of discs instead of
sometimes
spaces
Fig. 12."
End
Laminated
View
of Shuttle
the number
to
brass
solid in
cast
vary from
may
Stampings
for
ture.
Arma-
Shuttle
Armature.
of coils is determined
the cogs.
of spaces between
Fig. 8
in section a shuttle or H-girderarmature.
In
the number
shows
It is also built up
stampings of sheet iron strung on a steel
small machines
of laminated
this is cast
spindle. One coil only
armature.
Fig. 9 shows
solid.
be
can
a
two
good
coils may
armature
to
be
wound
wind,
as
wound
double
armature, also built of sheet
each arm,
be wound
on
may
or
ringsonly.
bolts attached
cogs and
Centre StampLaminated
for
ings
Shuttle Armature,
End
on
are
Fig. 11."
Fig. 13."
a
as
cogged ring or Pacinotti armature.
of rings stamped from thin sheet
be strung
may
wound
a
also is made
iron, which
the
over
also be made
may
shows
also be
can
on
a
shuttle
or
shuttle
Walker
iron
stampings. A coil
making four coils in all,
crosswise.
the coils
are
It is not
apt
to
be
a
of
DYNAMOS
i8
ELECTRIC
AND
MOTORS.
Fig.10 shows a laminated
shuttle armature
of a somewhat
improved form. The
stampings for the centre portionare of the ordinary
shuttle or H shapeshown in Fig.11, while the end stampings
take the shape shown in Fig.12. These are strung
and clamped togetherbetween two castings
two bolts,
on
shown in side elevation by Fig.10, and in end elevation
by Fig.13. The wire is wound over the central portion
or
web, and through the spaces at the end, the shaft
Leing driven securelyinto the end castings.
lengthand
uneven
resistance.
Binding-Post.
Fig. 14." Straight Pattern
Fig. 15."
Ball Pattern
Binding-Post.
Binding-Screws,etc. These are small clamps made
of brass,and cast or turned in various forms to suit
requirements.They are sometimes called connectors
used as convenient means
of connectingone
and are
"
"
part of
an
made
electric circuit with
in the
form
of
"
the rest of the circuit.
or
pillar
post and fixed
bindingby being screwed to a base,they are named
the
When
fixed
wires
to
two
proceedingfrom
posts."
so
a generator of electricity
as to form the two
polesof
the generator, they are
named
terminals."
The accompanying
illustrations will show at a glanceseveral
types of binding-screws.
as used for the terminal
Fig.14 shows a binding-post
When
used for this
polesof small dynamo machines.
purpose the post should be massive,the threads on the
When
a
"
"
INTRODUCTION.
well
screws
19
the hole for the wire left
cut,and
If these posts are nickel-plated,
they enhance
of the machine,and requireless care
large.
the appearance
to
keep
taper the post from the base
upward, whilst others round off the tops. This is merely
them
clean.
Some
makers
Fig. 16.
Fig. 17.
Figs. 16 and
a
of taste.
matter
twined
1 7."
Telegraph Pattern
The
wires
machine
are
the tang of the post and secured by a nut
the base of the machine.
Fig. 15 shows a ball
used for
pattern binding-post
Fig. 18."
Figs.16
are
When
for ammeters
and
modification
a
similar
This form of nut
Flat
a
Base
similar purpose.
Terminal.
pattern"binding"telegraph
instruments.
used for the terminals of telegraph
made large,
they are useful terminals
similar instruments.
Fig.18 shows a
terminal ; and Fig. 19
of the same
terminal furnished with a wing nut.
screwed and unscrewed
may be easily
and 17 show
posts. These
shows
the
around
beneath
neat
from
Binding-Posts.
two
DYNAMOS
20
without
workmen,
French
head
milled
pliers.
It
and
is used
by
them
so
with
in
commonly
met
with
favour
finds
of
aid
the
MOTORS.
ELECTRIC
AND
of the
instead
binding-screws
of
iff.20.
Nut
and
English
makers.
terminal,
in
used
of
wire
Leclanche"
two
brass
and
should
cast
have
be
on
to
as
used,
the
be
side
else
or
to
made,
enough threads
tightened on the
the
to
side
we
a
lug
should
thicken
it where
otherwise
these
allow
wires.
of
the
screws
to
Two
holes
to
receive
tube
These
sketch.
together.
pin
join
Thick
a
the
will
screw
not
nectors
con-
broken
brass
soldered
be
form
one
tube.
wish
and
nut
shows
21
of the
the
Connector.
tops of carbons
lead
brass
in
wires
simple
a
Fig.
the
shown
when
two
connect
in
from
in
tapped
useful
are
insert
made
screws
shows
20
batteries.
connector
drilled
or
to
Wire
Fig. 21."
Fig.
used
as
are
wire
Terminal.
Pin
tube
to
or
holes
contain
being securely
CHAPTER
IL
SIEMENS
DYNAMO.
Siemens
invented
THE
IN
1857, Dr. Werner
of
armature
so
called
of
an
is
easily made,
22.
Fig.
general
detail
in
Fig.
diagram
the
the
magnet
magnet
The
at
shows
M,
;
cores
cores
;
are
and
or
other
to
of
the
parts
of
the
often
are
shown
of
the
bolts
made
in
Dynamo.
Figs.
several
of the
by
a
machine
of
or
23
to
37
parts.
The
parts
posing
com-
the
machine
pole pieces ; c,
the
yoke to which
Y,
become
has
whilst
its
As
15.
field magnets,
the
attached
that
the
it
position
carcase,
M,
field magnets
Fig. 23,
suit the
22
forms
section
the
Fig. 8, p.
up,
Siemens
Fig. 22,
at
the
set
of
Outline
"
at
with
outline
An
skeleton, or
armature
and
girder, and
H
resembles
together
is shown
use
Siemens
is shown
wound,
general favourite.
show
This
girder.
of armature,
this form
the
as
its cross-section
because
iron
H
known
now
fo\m
simple
the
; A
c, the
the
being
field
field
screws.
to
the
form
shown
Fig. 24, in various sizes,to
required machine, as shown
at
SIEMENS
THE
DYNAMO.
23
form
and
throughout,the cores of one height and size,
with each other when upright. If slight
parallel
larities
irregutake them off
appear on the sides of the tunnel,
with
the rounded
face of the file. The
should also be filed round
of the
corners
and
smooth,to prevent
abrasion of the covering
on the wire whilst these are being
wound.
If the castings
are
shaped as shown at Fig.23,
holes must
be drilled and tapped in the top at a, 6,
to receive screwed studs to hold the yoke in its placeon
the field-magnet
Holes about \ in. diam. must
cores.
also be drilled in the lugsat c, d, e, /, to receive screwed
studs or small bolts securingthe armature
bearingsto
cores
Fig. 25.
"
Solid
H-girderArmature
commencing
to wind.
lugs. Two largerholes must also be drilled in tho
at g, h, to receive short coach screws
feet of the castings
base.
to their wood
used for boltingthe castings
The yoke to connect the field magnets, shown at Y
piece of iron plate,and must
Fig.22, is a rectangular
be bedded on the top of the field magnets'cores to hold
the
them
in the
positionIn
the small
Siemens
machines
makers
this separate yoke is dispensed
suppliedby some
with,as the top of one of the castingsprojects
the space between the two,
to bridge over
sufficiently
and thus forms the yoke. In the castings
suppliedby
have turned-upflanges,
also,the two projections
others,
these are bolted together.
shown
at Fig. 24, and
as
The
a
two
field magnets
similar way
by
must
bridge,so
the polesof
iron
an
magnet, between
be connected
as
in this
to form
which
a
or
in
shoe
horse-
the armature
will revolve.
The
armature
of the solid H-girderform
used
in
DYNAMOS
AND
ELECTRIC
MOTORS.
THE
machines
DYNAMO.
SIEMENS
Fig. 25. It is
is supplied with
is shown
at
speciallysoft iron, and
The
castingsfor the machine.
should be true and smooth,and
be rounded
should
of the wire
also
must
by
These
screwed
The
faces for the
to form
26 to 28.
smoothed
to
are
ends must
the
other
for the wire
the ends
covering. The rounded
be free from lumps, and
end to end.
true from
true
and
channel
casting of
a
of the web
prevent abrasion
faces of the cheeks
they must
also be
"be filed or turned
shown
spindle-holders
at
Figs.
secured to the ends of the armature
studs,and
holes must
be drilled and
tapped
to receive them.
Fig. 27.
Fig. 26.
Fig. 23.
Fig. 27." Section of
Fig. 26." SpindleHolder : End View.
Fig.28." Section of Spindle Holder
Spindle Holder.
and
Commutator.
largermachines,the armature is built up of purchingsof sheet-iron shaped as shown at Fig.11 (p.17),or as
These stampings are sold at prices
at Fig.29.
shown
rangingfrom 3s. b'd.to 10s. per gross, accordingto size.
shown
The stampings are strung on a steel spindle,
as
secured at each end by nuts, so as to
at Fig. 30, and
pinch the whole series of platesbetween them. The
result is to form a channel for the wire,and faces
In
for the cheeks of the armature, similar to
This laminated form
solid H-girderform.
tendency of
currents
the armature
in itself whilst
separated from
these
each
to
heat
that of the
lessens the
by generatingcross
working. The
other by varnish
laminations
or
paper,
are
and
cool. The
help to keep the armature
spindle
should be longenough to pass through the end bearings.
The spindle-holders
for the solid form of armature
made
o/ brass,either cast with a projecting
are
boss,
2
DYNAMOS
6
made
of
AND
ELECTRIC
MOTORS.
disc of brass with
piece of brass
tube fitted in the centre to give holding power
on
The spindlesshould be of steel,
the [spindles.
turned
in their respective
true and smooth, and fitted tightly
bosses of these spindle-holders
holders. The projecting
running againstthe bearingsprevent end shake of the
is employed,
armature
a laminated
armature
; but when
be turned down
the ends of the spindlemay
a littleto
or
up
a
shoulder for this purpose.
The
armature
bearings for
form
a
a
the
machines,are cast in gun-metal to the
Figs.31 and 32, or cut from sheet brass to
Fig. 29.
"
Laminated
"
strung
on
shown
form
at
the form shown
Iron
Fig. 30.
Iron Punching
for Shuttle
Armature.
sizes of
smaller
Laminations
Spindle
to
Shuttle
form
Armature.
Fig.36 (p.30),aud are secured to the ends of the field
in the slots shown
in the
magnets by long bolts resting
Fig.24. As the bolts run the whole lengthof the
lugs,
sides of the machine,they then clamp the front and back
bearingstogether.The bearingsfor the other forms are
made, but they are secured to the lugs of the
similarly
field magnets by screwed studs,
or by small bolts passing
form of
through holes drilled in the lugs. Whichever
bearingis employed, or however it may be secured to
be exactlyin the centre of
the machine,the holes must
at
the armature
may
run
no
tunnel,so that the cheeks of the
nearer
to
one
side than to the other.
The
field magnets
may
the bearingsput on, and the
its tunnel
tested.
armature
It should
now
be
runningof
bolted
together,
the armature
be centred
so
as
in
to leave
the cheeks of tlio
about -^oof 'an inch of space between
A space the
and the sides of the tunnel.
armature
THE
thickness of stout brown
is less than
space
DYNAMO.
SIEMENS
paper
this,the
is
27
enough, but
cheeks
may
bind
against
allowed,
If excessive space is
will be lost. If there appears
the sides of the tunnel.
part of the energy
if the
to
touchingthe sides at any
danger of the armature
it with a file.
and ease
particular
part,mark the place,
A very effective way to test the runningof the armature
is to paste a pieceof paper over
the cheeks,and then
revolve it in the tunnel.
On taking it out carefully,
the prominent
the abrasions on the paper will mark
be
a
parts,and these may
This
of
then be eased.
is wound
form of armature
with
coil
only one
"
will be a
tator
wire;;the commutator
two-part commutions,
(seeFig.33)" that is,one divided into two sec"
for each end of the wire coil. These
one
must
be insulated
insulated from
and handiest
well soaked
which
about
the rest of the machine.
serve
Therefore
can
other,and
must
also be
The
cheapest
substance available
insulating
in melted paraffin.Ebonite or
fibre will also
costly.
each
from
be
1 in. thick.
is boxwood
vulcanised
the purpose, but these
of boxwood
get a chunk
turned
Turn
disc
a
sections
are
more
\\ in. in diameter
this up true,with
a
of
out
and
hole bored
when driven on one
exactlyin the centre to fit tightly
of the spindles.Then get a piece of brass tube 1 inch
that exactlyfitsover
the boxwood, and force
in length,
The smallest sized machines take a comit tightly
on.
mutator
I in. in diameter.
If
now
this brass-bound
boxwood
disc
were
forced
on
spindleas shown at Fig. 28, it might work loose in
turn
down
the
time; so, to prevent it from slipping,
hub of the spindle-holder
enough to get a good face
boss to fit against,
then bore two J in.
for the boxwood
holes in the holder,
and fit them with two short brass
pins. When we have determined how the commutator
shallow holes may
the spindle,two
shall go on
be
the
bored
those
in the
inside face of the boxwood
pins exactly,and so
The ring of brass must
now
keep it from
be divided,
and
disc to
fit
slipping.
upon
the
Dl'XAMVS
2S
this is done
AND
ELECTRIC
will
MOTORS.
depend all other parts beingright
"the
If divided into
proper working of the machine.
two
the tube,
equal sections,
by sawing straightacross
the current
from the armature
would
be interrupted
abruptly, and sparks would be caused, which would
burn away
the brass ring and also the brushes.
soon
The
therefore be made
saw-cut
must
obliquelyor
the ring.
across
diagonally
But here we must guard againstmaking the division
at A on the left in Fig.34,for this would be too
as shown
would, in consequence,
oblique,and the interruptions
way
"
Fig. 31.
Fig. 32.
Bearings for Armature.
Fig. 31." End
Fig. 32." Section.
not
take
proper
one
direction
i in.
lines.
a
To
obtain
side of this line draw
line with
lines
on
one
lines
the two
two
space
hand
end
of the
line.
bottom
holes
between
on
each
these
on
the end.
top line
lines,from
two
Next, drill and
of the
side
countersink
line to
two
receive two
Turn
the
across
rightof the
small
very
Fig.34 (B),and put in
touch the spindlewhen
not
must
When
this has been done, the ring
driven well home.
be divided by sawing it through to the boxwood
may
small brass screws,
the screws, which
as
shown
the
the left-hand end
to
other
side of the brass
the disc over, and scribe two similar lines across
oppositeside. Now on both sides scribe a line
the
the
this saw-cut, turn the disc on
line diameterwaysacross
the centre,
scribe two
Now
exactlyin
a
each
on
time.
proper
for
draw
end and
and
the
place at
View
at
SIEMENS
THE
on
for the purpose.
The saw-kerf should
thin
out
well with
and
bridgedwith
a
Fig. 33.
The
bored, and
fine
"
the
Ring
for the
commutator
Fig. 34.
left-hand
"
a
hack-saw
and
little,
it is apt
or
file,
of metal
particles
Brass
holes
the
be widened
spindle,having placed it so
commutator
ring shall be
nearest
29
using a
alongthe diagonallines,
both sides
brushes.
DYXAMO.
cheek
get choked
to
the
from
worn
for Commutator.
be
now
fixing-pins
may
fixed in its place on
that the
the
on
of
the
saw-cut
side of
the
in the
the
armature.
Commutator, showing Divided
and
cleaned
Brass
coil
Two
Ring
Screws.
be drilled through the spindlesmall holes may
now
holder (asshown at A, B, Fig.26,p. 25). These are bushed
other non-conductor,and the ends of
with ivoryor some
throughthese are securely
fastened to the commutator
ring.
The brushes are long thin piecesof springybrass,
each side of the
copper, or phosphor bronze fixed on
the armature
coil wire to
commutator
to brush-blocks
the machine.
come
insulated from
Their duty is to pick up
the rest of
the
impulses
THE
A
very
good
DYNAMO.
SIEMENS
material
for
the
31
brushes
of small
and two or
is fine wire gauze cut into strips,
three thicknesses soldered to the ends of stout brass
machines
springsto
Three
ensure
proper
pressure
the commutator.
on
generaluse are shown at Figs.
38,39 and 40. That shown at Fig.38 is merely a pieceof
thin springbrass,shapedas shown, and fixed to a pillar
This is an
brush-holder.
objectionableform, as it
often gets out of order by wear, and cannot
be replaced
is an improvement on this
or adjustedeasily.Fig.39
form.
It is composed of thin sheet brass or hard
forms of brushes in
Fig. 38.
Fig. 40.
Fig. 39.
Figs. 38
of Commutator
to 40." Forms
Brushes.
cut to the form
shown, with one end
slit into fingers
and a slot
to the length of 2 or 2| in.,
cut in the other end
The
to facilitate adjustment
soon
wear
fingers
away, and must then be replaced.The
brush shown in Fig.40 consists of a pieceof hard spring
brass,to one end of which is soldered a pad of copper
hammered
wire
kept
which
This bears on
the commutator, and
is
gauze.
in contact with it by the stripof springbrass to
it is soldered,
the
Fig. 36
a
copper
brush
for this
;
stripbeing curved
This pad is most
purpose.
it does
not
cut
away
as
shown
at
effective as
the commutator
like
spring brass and copper, and it is easilyadjustedor
replacedif fixed in a brush-block with clamp,as shown
at Fig.37.
The position
of brushes for shuttle or H -girder
armatures
is a matter
of considerable importance. It does
not
that
matter
how
the commutator
point is settled by
holdingthe brushes. But
is fixed to the shaft ;
the most
convenient way
of
the rule that must
be observed
DYNAMOS
32
AND
is that" When
the
two
electrically
oppositethe
the brushes
rest
must
ELECTRIC
MOTORS.
cheeks
the
two
the
on
of
armature
are
of the field,
pole-pieces
insulating
stripson the
commutator.
In
this
Fig. 41
dotted
lines ; but
slight" lead ""that
a
anglein
small
This
moves.
when
not
positionis shown by the brushes in
the brushes are given a
in practice
is,they are moved forward through
the direction in which
bringsthe brushes
the
insulating
strips,
exactly face the
of the armature
the cheeks
littleafter
but just a
pole-pieces,
they have passedthe
line.
centre
Fig. 41." rosition of Brushes
brushes
The
with
this lead
lines,with
through which they
full black
of
machine
is at
work,
others ; for
centre
a
have
this lead
amount
than
on
the commutator
some
shown
Armature.
in
Fig. 41 in
line showing the angle
are
been
only
can
for
for Shuttle
turned.
be
The
found
armatures
when
exact
the
requiremore
instance,a rather hard solid shuttle
lead than one
built up of
requiremore
have just
separate punchings. The brushes should
enough lead for the machine to give its full current
without sparking. Just a trifletoo much
too little
or
lead may
easilybring about sparks,which not only
armature
mean
and
may
of power,
commutator, and
waste
Before
free from
winding the
lumps, and
but also eat away
both brushes
should therefore be avoided..
armature, see that the channel is
the ends of the web are smootlj
SIEMENS
THE
DYNAMO.
33
largeenough to envelopthe web,
and coat this with good shellac varnish.
Lay the silk
evenlyto form a bed for the wire,and varnish the silk
and the channel,
and when the varnish is dry proceedto
Then
cut
a
stripof
wind
on
the wire.
silk
will be all the better for the
This
soaked in hot
previously
melted paraffin.Commence
windingas shown at Fig.25,
is wound,
as a reel of cotton
p. 23, lay each coil evenly,
of
until the requiredamount
and wind close and tight,
in hand
purpose
if it has been
wire has been wound
above
the
stands
up
cheeks
above
The
on.
of the
the
wire coil must
If
armature.
not
stray layer
a
threatens
others,and
stand
to
knock
againstthe sides of the field magnet tunnel whilst being
it must be pressedinto its placewith a pieceof
revolved,
smooth wood.
Then bringthe two free ends to one end
of the armature, put on the spindle-holder
(Fig.26,p. 25),
bringthe ends through the ivory-bushedholes A and B
made
for this purpose,
put on the commutator, and
solder the two ends of the coil to the two sections of
the
holder,and
shows
Then
commutator.
a
lettered
put
the armature
is
follows
:
"
holders ; c, commutator
w, web
;
s
other
spindle-
complete. Fig. 35,
section of the armature
as
the
on
thus
finished.
of armature
s, shaft
or
p.
30,
It is
spindlespindle; and p,
; E,
drivingpulley.
Whilst winding the wire on the armature
or the field
magnets of a dynamo, great care must be exercised to
and each
get each coil of wire close to its neighbour,
layerof wire regularand close to the layerbeneath,for
this will depend the full efficiency
of the machine.
on
Slack and irregular
loss of power,
winding will cause
and this is specially
observable in the winding of the
armature, where cross winding will not only prevent a
maximum
number of coils beinggot in a givenspace, but
will also cause
currents in the wires.
cross
Nevertheless,
whilst givingall attention to the tightness
and snugness
of the winding,it is possible
to be too zealous in this
and fall into the more
serious error
of pulling
direction,
the wire so tightly
the iron ends of the armature as to
over
DYNAMOS
34
ELECTRIC
AND
MOTORS.
the iron to cut into the
cause
coveringof the wire. One
of the covering,
however small,
will render
electrical contact will be made
as
useless,
such abrasion
the machine
through the
iron of the machine
well
as
as
through its
wire coils.
Such
and
accidents
to detect
of
of
are
frequentoccurrence,
them
or
galvanometer,
insulation
these
as
it is necessary
to have
small
a
current detector,
and with it to test the
the
covering as the winding proceeds.
Almost any pricemay be paid for a galvanometer,
from
2s. 6d. up to "10, accordingto the value of material and
workmanship in the instrument ; but a plainand simply
constructed one, good enough for this purpose, can
be
plete
got for 10s.,or perhaps less. To test the wire for cominsulation whilst winding, connect
of
a free end
it to
one
stud
to
Bunsen
stud of the
terminal
one
or
galvanometer ;
a
of
bichromate
length of copper wire
battery. With the end
of any
whilst
part of the
connect
the other
good battery(one
will do very well),
and
a
to
the
other
terminal
cell of
a
attach
a
of
the
of this wire touch the bare iron
armature
(or of
the field magnets
needle of the galvanometer
winding them). If the
it may
be taken for granted
is deflected,
that the wire coveringis abraded,and each coil must
until the
be unwound
faulty place is discovered.
Such faults are best repairedwith a thread of unsoaked
in melted
silk or
soft darning-cotton,
spun
around the abraded
and wound
spot. If the
paraffin
at all when
the
galvanometer needle does not move
iron is touched with the batterywire,we
may be fairly
certain that the coil is insulated from
the iron of the
field magnet core, or of the armature, as the case may be.
Greater care is needed in winding a laminated armature
than in
the end
one
solid core, since the edges of
liable to cut through the protecting
having
a
platesare
coat of silk and coveringof the wire if this is pulledtoo
also will be
the edges. Some littledifficulty
over
tightly
the coils of wire to lieclose to the
in getting
experienced
spindlewhilst winding them on one side. This may be
THE
SIEMENS
by tyingeach
overcome
DYNAMO.
coilback with
a
35
short
spindlehas
Manchester
winding a laminated H-girderarmatumfora
be preventedfrom slipping
at the
the coils may
field,
at
ends by bending forward two of the laminated plates
each end, so as to form two flanges,
againstwhich the
coils can rest as againstthe sides of the end slot in a
solid armature.
As there are no spindle-holders
through
until the curvature
which
to pass
of the
pieceof tape,
been passed In
the ends
of the coil
we
have to fasten
direct to the sections of the commutator, to the
inside edgeaof which they should be secured by solder.
them
It will also be
advisable
to
tie the
ends
down
to
spindlewith a few turns of tape, to prevent the
outer coil from shakingloose in working.
Before winding the fieldmagnet cores, it will be necessary
to prepare them for the wire by wrapping around
them a layerof silk ribbon well soaked in melted paraffin,
appliedto the iron warm, and then made quite smooth.
The wire should also be prepared for winding by first
dividingthe allotted quantityinto two equal parts,
making these into hanks or coils largeenough to go loosely
stoneware
over
a two-gallon
jar,and then well soaking
them
in melted paraffin.The wire for the dynamos
in the table on
be divided by
specified
p. 24 may
measurement, if it is found inconvenient to divide it by
that No. 22 S.W.G. d.c.c.copper
weight,if we remember
wire measures
125 yards in the Ib. The wire may
be
wound
on
by hand if the worker is unprovided with
suitable apparatus,but it can be wound
more
regularly,
in a lathe,
of a special
or by means
smoother,and tighter
winder,which can be easilyand cheaply made up for
the purpose from a few scraps of wood, a few bolts,
and
Centre the field magnet casting
in the
a winch-handle.
lathe,and when it runs true,proceed to wind on the
the
wire.
If the hank
of wire has been
placed over
a
bottle filledwith water, the coils will
the wire is wound
on the casting.Commence
stoneware
as
easily
glazed
slipoff
the channel
or
bottom
end of the
core
; wind
some
at
seven
DYNAMOS
36
ELECTRIC
AND
MOTORS.
eightinches of the wire on a pencilto form a close
spiral,to be stretched out after winding to form
connections.
Lay this close to the bottom end, take
turn
around
the casting,and
the spiral
one
secure
with
Wind
to this turn
a
piece of strong twine.
the coils evenly side by side,
within two
and when
on
inches of the end,lay in two four-inch lengthsof tape
or
the
under
last few
leavingthe
ends
Fig. 42.
the
there
hanging.
will be
Before
ends
no
ends
all the
When
free end
to
each
of
piece of
stout
wire
has
twine.
first
pressure
are
thus
wound
on,
of the
bound,
top layer sinking in
it.
been
or
coils,
Serve
the
over
coils of the first
the
layer
danger of the
of the
one
complete.
down
under
the coils of that beneath
between
of the core,
winding back with
the last few
secure
slippingaway
If the
outside
Siemens-typeDynamo
"
thus
layer,and
layer from
the
on
layer,bring the
next
next.
coils
the
tie the
the core, with a
other field magnet
to
tion
testingeach layerfor insulathe work proceeds; then coat the outer wires
as
and set them aside
with a layerof sealing-wax
varnish,
of some
forms of field magnets
to dry. As the cores
core
in
a
similar
manner,
THE
SIEMENS
37
this method
of taping
unprovided with flanges,
just described will be found very convenient in preventing
but
the
end
of
coils;
flangesare
slipping
be introduced,
where
these can
as
they
preferable
but also protect the coils
not only prevent slipping
from possible
injury.
The various parts having been prepared,
they must
are
Fig. 43." Magnetising Field Magnets.
now
be fitted together.It is well known
that
a
straight
bar magnet has two oppositepoles"one
at each end.
One of these is called the north pole of the magnet,
its oppositebeing the south
pole. If now we bend the
bar in the shape of a horse-shoe,
the two poles are
each other,but they still preserve
brought near
their characteristicopposite
polarities.
If we wind an insulated copper wire around a straight
bar of steel or of iron as in the lefthalf of Fig.43,and send
electriccurrent in the direction of the arrow, through
an
the wire,we shall find that the lower end N of the
434360
SIEMENS
THE
DYNAMO.
39
edges,planed,and polished,
The completemachine
to ensure
a finished appearance.
is illustrated at Fig.42, p. 36.
of its design, this type of
the simplicity
From
lends itself readilyto illustrate how the wires
machine
of a dynamo should be connected.
Figs. 44 and 45
show two distinct methods of connectingthe wires. The
may
be
at the
trimmed
Fig.44." Diagram
of Series
method
shown
as
a
by
of Shunt
Fig. 45." Diagram
Connections.
Connections.
the full lines at
series machine
"
that
Fig.44
is,the
is called
necting
con-
field magnets,
the armature, and the outer circuit may be regardedas
three cells of a battery,and the whole connected up
one
after the
other
in
one
circuit.
through the field magnet
circuit is completed. When
pass
magnet
wires
other end
the
is connected
to the brush
diagram Fig, 44,
B,
to
as
the
No
current
can
coils until the
one
the
shown
machine
of
end
brush
by
the
field
A, and
dotted
will
outer
be
the
lines in
short-
DYNAMOS
40
But
circuited.
and
it
take
hanging
as
form
the
attached.
in
Fig.
in
that
in
the
machine
with
the
with
of
machine.
circuit,
in
and
is
the
because
within
certain
better
coils
and
these
going
method
of
the
limits,
combination
suited
Fig.
kept
the
of
to
this
correspond
coils
those
in
the
of
connected
terminal
in
field
force
poles
part
the
coils.
adopted
electric
generated
Compound
shunt,
The
letter
Fig.
44.
of
outer
magnet
incandescent
and
field
both
divided,
constant.
series
machine
generated
occasionally
motive
only
lamps.
work
the
is
connected
the
now
be
then
are
running
purpose.
to
the
connecting
electro
wires
the
current
the
must
arc
the
the
through
for
the
are
is
through
part
circuit
form
circuit
intended
dynamos
a
the
which
The
going
lamps,
this
brushes,
current
This
of
binding-screws
the
of
will
which
connecting
through
ends
two
the
the
of
piece
screws
to
working
part
passes
The
magnets.
for
as
is, only
"
machine,
c,
binding-
two
connecting
method
a
the
at
the
another
working
of
cases,
shows
shunt
the
wires
take
to
lines,
or
method
special
45
of
outer
This
suitable
full
the
then
that
the
poles
the
from
of
one
connect
by
two
MOTORS.
binding-screw,
and
B,
break
we
a
shown
screw
wires
if
to
to
ELECTRIC
AND
is,
ing,
wind-
is, however,
references
in
III
CHAPTER
THE
IN
1871
ring of
soft iron
Fig.
in
sections
use
a
this
46.
since
ways,
but
still known
many
of
which
modified
patent expired in
The
made
he
and
as
wound
altered
the
not
was
able
was
birth
the
wire
a
Complete.
iron,he
gave
armature
copper
Dynamo
Although
it.
over
the
as
insulated
Gramme
"
ring armature
modification,
armature
with
wires
used
vented
in-
Gramme
named
he
in which
dynamo
a
electrician
French
a
DYNAMO.
GRAMME
the
to
in
many
Gramme
first to
to
patent
form
of
different
ring.
The
1884.
modifications
of
Gramme's
iron
ring,
ring itself,must, however, be
in 1860
regarded as developments of a discovery made
by Dr. Antonio
Pacinotti,Professor at the University of
including
the
Gramme
DYNAMOS
42
Pisa,who
sixteen
and
make
armature
an
winding
insulated
copper
efficient
most
a
an
between
wire.
iron wheel
the
cogs
Here, then,
the firstringarmature.
Some
dynamo
a
cogs,
coils of
sixteen
was
he could
by employing as
dynamo
with
that
found
MOTORS.
ELECTRIC
AND
will be
small Gramme
The
carcase
Fig1.47.
and
it is
of a Gramme
generalappearance
gatheredfrom Fig.46,which represents
machine complete.
of the Gramme
dynamo differs in form
idea of the
Iron
from
structure
given
"
in
Carcase
of Gramme
that of others.
Dynamo.
A
generalidea
of
Fig. 47, where
s, s, represent the iron
standards or supports ; c, c, c, c, the field magnet cores
without flanges
between which
; and M, M, the polepieces
the armature
revolves.
Soft iron
can
castings
be
cheaply
and as probablythey will be received rough as
obtained,
from the foundry,
they must be put into shape
they come
and fitted for use by the dynamo maker himself. The
firstthingto be considered and taken in hand will be
of which is shown
the standards,
at Fig.48, fitted
one
with a bridgefor the brush -holders. It will be seen, on
to Fig.47,that each standard has two
referring
ing
projecteach
side.
The
of
these
are
uses
: in
lugs,one on
one
standard
of the
DYNAMO.
GRAMME
THE
support the bridge
to hold the bolts which
and
brush-holders,
43
in the other standard
to hold
bridgefor the brushsent with
rocker bearingmay be one of the iron castings
the face-plate
be mounted
This must
the carcase.
on
the boss bored to allow the spindleto pass
of a lathe,
through,and turned on the outside to hold the rocker of
In Fig.48, the holes F, F, above and
the brush-holder.
for the bolts of the
below the bridge (marked R) are
field magnet cores
to pass through. It is essential that
The
the terminals of the machine.
Fig. 48.
"
Face of Standard
Brush-Holders.
Inner
flanged ends
magnetic contact
with
will be advisable
to
the
diameter
of the
bearingsurfaces
of
core
for
the
must
be bored
but
should
cores
the iron of the
Bridge
be
for
perfect
it
so
standards,
in
surface the
rough iron within the
flangesshown in Fig.49, to form
the brightends of the turned core
flanges. The other standard
similar manner,
plugged with
with
must
be treated in
now
in this the holes in the
ebonite,to
hold
the
in the feet of the
terminals.
be
Holes
to receive
standards,
bolts for
to
The
standard
the machine
fastening
slots in each
cross-shaped
lugswill
a
a
bench
or
are
to the floor.
intended
to
DYNAMOS
44
hold the brass
portion of
ELECTRIC
AND
which
bearings,
the
slot,and
MOTORS.
fitted into the lower
are
held
in
small
positionby
wedges.
The
one
field magnet
cores
with the cheeks,or
and
with
the
(Fig.49) are
pole pieces,and
best cast
the
flanges,
at each
wrought-ironbolt embedded
as
castingwith the threaded part projecting
a
is then
Perfect contact
this is
and
continuitybetween
which
clean surface contact.
bolt the
cores
nicks with
a
and
cores
with
fitted to the
pins screwed
projecting
cheeks made
to hang
a
bright,to ensure
with their polepieces
Flanges
and
Pole
standards,the
and
fitted with
in line with
standards
fileon
and
true
Both
Core
Magnet
be
now
may
order
all the parts,
to maintain
magnetic
the
flangesshould be turned
"
shown.
pole piecesand the standards
their yokes. The
outside faces of the
form
Fig. 49.
end of
between
ensured
important in
in
up
flangesand
each
Pieces.
ends
of the
nuts, and
other.
the
Then
tight,mark
standard
by small
the positions
core
through
to the depth
and drill on each side of the
piece,
each flange |-in holes into the standards
of i in. Iron pins fitted in these holes and fixed in the
the parts together
flanges,will form a guide in fitting
after the cores
wound
with wire,and ensure
that
are
the cores
shall be placedin their rightposition.
of each
The
armatures
made
now
They
are
of iron
now
at
Gramme
in the
wire,as
built up
of
Fig. 50, with
peripheryof each ring. It
as
shown
of small
machines
are
not
originalmachines.
ringsof sheet-iron,
shaped
a
number
of cogs
will thus be
seen
on
the
that the
GRAMME
THE
DYNAMO.
45
is
The
a Pacinotti ringarmature.
practically
number
of cogs and intermediary
spaces are arrangedon
each machine to suit the designer,
and may be any even
and so on.
number, such as ten, twelve,fourteen,
sixteen,
armature
In the small
the
machine
laminations
twenty-fiveto
up
is
as
range
the
follows
:
alternate cogs of each
Fig. 50.
These
must
"
shown, the number
Laminated
in thickness
inch.
The
small
holes
method
Punching
of
drilled
are
as
lamination,
Iron
from
is ten, and
fourteen to
shown
for
Ring
at
building
through
Fig. 50.
Armature.
be \ in. or f in. in diameter,
holes may
but they
exactlycoincide with each other throughthe whole
to admit
rods on which
as they have
plates,
the laminated
platesare strung. The rods should be
of a material of high electrical resistance,to avoid
when
Both
at work
eddy currents in the armature
be threaded,and fitted with
ends of each rod may
Ebonite bushes and washers
suitable hexagonal nuts.
the nuts and the armature
should be placed between
spidersand plates.
be coated with good tough
The platesmay
next
number
of
GRAMME
THE
cogs
DYNAMO.
filled with
will be
coil of
a
end
of
it
Portion
of
Ring
47
wire, wound
by
through the space between
of the supportingspider and around
the
the arms
thickness of the laminations,
shown
at
combined
as
less than that
Fig.52. As the space inside is slightly
between the cogs there is a danger of the inner part of
the wire space of its neighbour.
coil encroaching
on
one
wooden
To prevent this,
guides may be employed,fixed
and secured to other
the cogs on the outside,
between
wooden
guides inside the armature by suitable screws
passingone
Fig. 52."
passingthrough
the
also in section at
A
Armature
ends,as shown
B, A B, Fig.50.
Fig. 52, and
These
effectually
coils whilst the wire is being
of the wire
prevent slipping
wound
as
on, and
the work
can
lower
of
the
cross-slit receives
wedges,
upper
to
part
lubricator.
a
hole
at
one
space to another
proceeds.
the standards.
part
from
be moved
Before ; preparing the
it will be advisable to
placesin
ready for Winding.
hold
of
the
The
stem
in the
spindle for the armature,
fit the bearings in their
These
should
in
crosses
the
be fitted in the
standards; the
plate, fixed
bearings down,
iron
an
the
cross
forms
a
space
in
and
for
of this lubricator is screwed
wedge-plate,and
with
the
the
to fit
the oil is conducted
DYNAMOS
48
ELECTRIC
AND
MOTORS.
hole in the upper half of the
turned true,and fixed securely.
through a
are
The
and
spindleshould
length suitable
to the
shape shown
will
be made
of mild
to the machine
at
which
bearings,
in
The
Fig.53.
of a size
steel,
hand, and turned
left-hand
end
from
in the left-hand
bearingof the machine,
shown
at Fig. 46 (p.41),and carry the driving-pulley.
The two shoulders at B and c are for the bearingand the
boss of the armature
and E
D
: At
spiderrespectively
holes must
be drilled through the shaft and fitted with
pins,which projectand fit the key-ways left in the
and thus prevent the armature
from turning
spiders,
the spindle. The space between
round on
and the
E
screwed part at s will be occupiedby the commutator
;
A
to
B
run
Fi". 53.
"
the remainder
Armature
of the
Spindle of Gramme
spindlewill
bearing,Fig.46.
A hexagonalnut must
to bring the commutator
in
close contact
be
and
part
any
alteration
square
between
whole
smooth.
spin
lathe.
The
the
other.
spindle
it,put the
ture
arma-
The
on
it round
done, with
This
s
to
a
that
see
to make
half-inch
off any roughnesswhich may
appear
the armature
make
the
to
cogs, so as
If the cogs
spaces
coated with varnish
do
between
and
not
commutator
properlyclear
be trimmed
the cogs
the armature
preparatoryto being wound
The
the thread at
spidersof
the projecting
pole-pieces,
parts may
a
right-hand
will be the time
now
required.
file trim
or
on
true,as
runs
on
the armature
being prepared,next mount
spindle into its place,and
every
the
each
with
in the
run
fitted
Armature.
should
the
off in
now
set aside to
be
dry,
with wire.
is furnished
in number
corresponding
with
with
several
the coils
on
ments,
seg-
the
THE
when
is constructed.
seasoned
In
the
for
2 in. in
less than
a
hole
fit the
to
cylinderof boxwood
How
Commutator
Fig. 55."
cut
out
more
to
convenient
and
diameter,
On
this
of the
It would
be
possibleto
Fig. 56." How
to insulate
one
the outside
of small
3 in. in
Commutator
by
complete.
the bars
Ring.
fiteach
the commutators
Fig. 54.
well-
solid hub
a
spindle.
armature
mount
one
out
to turn
length and
appearance
it
how
piece of
a
Ring Armature
to divide
these bars
and
brass,
a
in
shown
as
of
centre
boxwood, largeenough
Fig. 54. "Commutator
bore
49
Fig.54 gives a generalidea of its
whilst Figs.55 and 56 show
finished,
armature.
of not
DYNAMO.
GRAMME
from
of the
dynamos
accurate
a
tator,
commu-
Segments.
sheet
of hard
cylinder
;
but
be built up
method.
Procure
may
by
a
piece of gun-metal tube,with sides quite \ in. thick,
and of a diameter largeenough to fitover
the box-wood
hub, after a lightboringcut ha? been taken through the
DYNAMOS
50
ELECTRIC
AND
inside to render it smooth.
long enough
Now
as
to
divide the
there
are
have
Cut
the
cover
ring into
cogs
MOTORS.
off
pieceof the tube
hub, and fit it tightlyon.
sections
as
equal-sized
many
a
the armature.
on
If there
ten
are
if
sections,
fourteen cogs have fourteen
but each section must be equal,so as to form a
sections,
cogs
ten
series of
The
equal-sizedbars all round the hub.
division lines should be deeplymarked with a sharpsteel
and then nicked with a hack-saw,as shown
at
scriber,
Fig.55. Next drill a small hole through each end of
each section and into the hub
mouth
of each
each,as shown
a
saw
hole,and drive a
in Fig.55.
This
separate each
allow the
to form
nearly\ in.,
to be placedbetween
may
a
Procure
each section.
to fillthe
thick black lines at
into
all
fibre
sheet fibre
some
screw
the
round, with
its neighbour,and
hub to the depth of
substance
insulating
The insulating
stance
sub-
hold for the
thicker than the saw-cut
largeenough
done
the boxwood
be either vulcanised
; countersink
short brass
section from
to enter
saw
beneath
or
or
asbestos millboard.
a
millboard,
trifle
and from it cut slips
divisions,
shown
cuts exactly,
as
by the
Fig.56.
the screws
of each section,
ease
Slightly
wedge the
strips
firmlyinto each saw-cut, then
preparedinsulating
again,and so pinch each striptightly
tightenthe screws
the edgesof the sections. When
each side between
on
the hub in a lathe,
and true up all
this is done,mount
or with a rough
parts with a sharptool,
rough projecting
fileat firstand then with
a
smoother
segment of the commutator
Each
connected to the ends of two
means
manner
file.
of
:
"
making
Choose
a
coils of
connection
either end
the
of the commutator
be
following
to
go
end of each section
hole
to
receive
a
hard copper
wire,and cut it up into two-inch lengths.Flatten one end
the other
of each length as shown at Fig.57, and screw
screw.
Next
take
a
No. 12
to
wire,and the best
is in
next the armature, and in the extreme
drill a -^ in. hole,and tap each
lengthof
will have
S.W.G.
ends to go into the tapped holes made
to receive them.
GRAMME
THE
Tin
the screwed
and
they
as
givingeach
a
arc
ends
DYNAMO.
of each
done
touch with
connector
into
them
screw
the
51
with
solder,
their
places,
to make
soldering-bit
the
solder run, and fix the connector
firmlyin its place.
A disc of vulcanised fibre,
slightly
largerin diameter
than
of
the
should
now
fibre. This
piece of |-in.sheet
a
the end of the commutator
between
to
spider,
armature
the
commutator,
from
one
the
ensure
the other
when
be
turned
must
be
and the
out
placed
of the
arms
complete insulation of
they are tightenedup
the
spindle.
Before winding
on
how
this
much
the wire
the armature, calculate
for all the coils,
and divide
will be needed
quantityequallyamong
Fig. 57.
"
Copper
Connector
on
them,
for Ends
to
each
ensure
of Armature
coil
Coils.
resistance. A table at the end of this
having the same
suitable to each size of armature.
chaptergivesparticulars
In this table only three sizes are
:
specified
namely,Nos. 16,20,and 22 s.w.G.
By remembering that
No. 1C cotton-covered
copper
wire
runs
about
25
yards
in the
No. 20 runs
and No. 22
80 yards in the lb.,
lb.,
120 yards in the lb.,
runs
we
can
easilycalculate the
lengthof wire for eacli coil by multiplyingthe number
of yards per lb. by the number
of Ibs. to be used,and
dividingthis by the number of coils to be placedon the
For instance,
armature.
supposingwe have to use 4 Ibs.
of No. 20
=
320
S.W.G.
; and
on
an
with 10 divisions
armature
divided by
this,
10
(thenumber
of
:
"
4 X 80
divisions),
give 32 yards to each division. Measure off the
and roll the wire up into hanks,containing
lengthfor each coil,
will
one
coil in each
hank.
Place
each
hank
in
a
and let it soak
containinghot melted paraffin,
for several minutes,then hang it up to drain dry.
shuttle of tough hard
Next
make
a
wood, to
vessel
DVXAMOS
S2
MOTORS.
ELECTRIC
AND
the
This shuttle may
shape shown at Fig. 58.
9 in. in length,and
of a width suitable to the
of the spaces through which it has to pass ; the
in the ends must
also be cut large enough to
the whole
with
coil of wire,and this Avill vary
size of the armature
smallest
X
on
1 in. X
in width.
to
be
The
wound.
whilst
the cotton
silk
or
winding the coil. This shuttle
58.
Shuttle
Wooden
"
This is a two-handed
a
The
the
low trestle between
take
the
must
ing
cover-
be
now
then
and
winding Armatures.
it is necessary
ringmay
armature
winder
to have
and
be held.
his assistant.
edgesof the spaces between the cogs and
ring,to detect any rough placeslikelyto
the
Examine
inside
for
job,and
helperwhilst doing it.
on
gaps
shuttle for the
neatlywound with one of the coils of wire,
it to the armature.
we
are
ready for transferring
a
size
the list (on page 59) should measure
9 in.
and should have gaps | in. deep by jjin.
i in.,
All edges must
be rounded
and made
quite
smooth,to prevent chafingof
Fig.
be
the
abrade the wire
filethem
covering. If
for in
down"
varnish would
be
so
injured"but
piecesof broad tape, stuck
hot paraffin
wax.
Begin winding on the
spaces, next
to
an
arm
of the outside end
justto
spider,
of these appear, do not
doing the dried coat of shellac
any
on
cover
after
them
with
being well
left-hand side of
of the
spider. Wrap
of the wire
around
the
soaked
one
a
short
in
of the
few turns
arm
of the
hold it in its place,
pass the shuttle to the
the armature, and get him to pass it back
through the ring; laythe coil up close to the left-hand
assistant
it moderatelytight; then pass the shuttle
who will return it throughas
againto the assistant,
cog, and
over
over
before
draw
(seeFig.52).
Thus
proceed,layingeach
coil close
GRAMME
THE
DryA.\ro.
againstthe
one
to reach the
commutator, fasten down
53
precedingit,until the space between
the two cogs has been covered by one
layer. Then
wind back from rightto left until this layerhas been
closelyand regularly
^coveredwith another layer. If
usinglargewire,such as No. 20 or No. 16, there will be
a
tendency on the part of each coil to bulge in the
of the space.
This bulgingmust
be kept down
centre
from the start by gently tapping the bulging part
(whilst tighteningthe coil)with a small wooden
mallet,or by placing a piece of wood on the wire,
with
hammer.
The
and strikingthe wood
wire
a
be kept level and
must
compact in the outside
in the inside this may
be disregarded.
space, but
Whilst winding the coil test it frequently
for insulation,
and make
good each fault before going on further,
of the
for leakage here will destroy the efficiency
machine.
When
the first coil has been wound, leaving
the wire ending on the side of the space oppositeto
that where it commenced, and with enough projecting
the outside of the coil with
Remove
p.
the
47),and
guidingpiecesof
coat
This
manner.
some
the wire and coat
varnish.
quick-drying
wood (shown in Fig.52,
the inside coils with varnish in
will
help to
a
similar
fix the wire
in its proper
insulation of one
coil
better
and also secure
position,
receive
from its neighbour. The whole wire should now
the commencing end of each
coats of varnish,
one
or two
coil being also painted with a distinctive colour to
when
facilitate its recognition
connectingthe ends to
bars.
the commutator
When
the varnish is dry and
mounted
hard,the
armature
may
the
must
spindle. The commutator
be forced on tightin its place,and fixed close to the
fibre washer by screwingup the nuts on the threaded
end of the spindle. It is well to have two
nuts, one
to lock the other and prevent the parts from shaking
be
loose.
one
on
The
coils may
be connected
to the comnow
mutator
bars by solderingthe commencing end
of
coil and
the
end of
finishing
its
neighbour to
it*
THE
the whole
they pass
The
machine
layerof wires togetherhere
made
there,where
and
the cogs of the armature.
brush-holders
and brushes for
fixed to the
not
are
in the
in the
attached
55
over
is done
as
DYNAMO.
GRAMME
form
small
of
this
bearingsor
Siemens
machine
rocker,pivoted on
standards,as shown
a
one
of the
(p.43),and
are
therefore free to be moved
desired.
as
casting,
shaped
in the
the
centre
as
shown
is turned
bridgeshown
at
The
at
to
rocker
A
pillars,
; they are
a
bridge
at Fig. 48
round
is often
Fig. 60. The
fit looselyon
Fig. 48.
hole
of
to the
to
commutator
type
an
the
iron
large hole
the boss of
is drilled and
c
Fig.
60." Rocker
for Brush-Holder.
the crown, as shown
at c, Fig.60, to receive
which
is used to fix the rocker in any
set-screw
tapped in
a
requiredposition.Two " in. holes,B, B, are drilled
these holes are pluggedwith ebonite,
through the rocker,
and through each plug a \ in. hole is drilled to receive
the screwed ends of the brass spindles,
s, s, which carry
The spindles
the brush clamps,c, Fig.61.
be made
may
of | in. brass rod, and the outer ends should come
within \ in. of the inner edge of the commutator.
The
inner ends must
be turned down
to go through
the ebonite plugs in the rocker,and screwed
to take
each side of the rocker,
shown
a hexagonal nut
on
as
These nuts must
be insulated from
at A, A, Fig. 61.
the rocker by washers of ebonite or of vulcanised fibre.
The oppositeends of the spindlesmust
be fitted with
more
two
hexagonal nuts to hold the brush clamps ;
these are of gun metal,shaped as shown in Fig.G2. The
Dm
56
AMOS
AND
ELECTRIC
partof this clamp is formed
upper
which
are
made
of
stripsof
whatever
MOTORS.
to receive the
hard
brushes,
brass,copper
gauze,
phosphor bronze,or
may
The stripsare held by a brass plateplaced on top of
them, and secured by the thumb-screw d. Holes are
bored in the lower part,as shown at e, e, for the spindle
to pass through. The clamp being thus free to move
around the spindle,
of the
togetherwith the movement
material
Fig. 62.
"
Clamp
be chosen.
for
holding
Brushes.
Fig. 61."
and
Brush-holder
Rocker
complete.
quired
rocker,allows the brushes to be adjustedto any reangle. A small brass staplesoldered to the
spring
inside of each clamp receives the end of a spiral
due pressure
and this ensures
threaded on the spindle,
of the brushes on the commutator, whilst it also keeps
at the end of the spindle.
the clamp in its proper position
the .brushesit is found advisable to move
In adjusting
of
of an insulated handle made
the rocker by means
end in Fig.61. The
at one
ebonite or vulcanite,
as shown
handle may be attached by screwingit on a short stud
GRAMME
THE
DVXA.MO.
57
fixed in the end of the rocker.
A similar handle may
fixed at the other end if desired.
be
machine the wire
In the field magnets of a Gramme
in four separate coils,
will be wound
it will be advisable
so
divide the total
to
into four
quantityof
equal parts,and
in the
of
case
to
the
each
each part as recommended
wire for the armature.
of
it should
wax,
as
it will
from
a
a
north
core,
off
The
method
a
the
be
it
to
Twist
over
the
one
stout
wound
Dynamo.
soaked
the armature
is shown
core
Gramme
at
in
wooden
easilyfrom a
of winding so
the armature
speed.
cross
on
more
pole pieceabove
Mount
to slow
be wound
run
hank.
piecebelow
has been
coil of wire
be used
to
treat
Fig. 63." Winding Field Ma^nete
After
wire
and
paraffinbobbin,
bobbin
as
a
to
than
secure
south
pole
Fig.63.
in
a
end of the wire
pole piece,take
one
lathe
A
geared
round
turn
the
round
DYNAMOS
58
AND
MOTORS.
ELECTRIC
piece of
Then proceed to wind on the wire evenly and
twine.
with the coils close side by side,from the
regularly,
pole piece on the rightto the end of the core at the
on
to and fro,until all the wire has been wound
;
left,
of
with
a piece
tie the last coils togethertightly
then
its
core, and
own
tape
narrow
the end
to
prevent them
is free.
E
Fig. 64.
"
tie this turn
Next
from
unfasten
Connecting Fields
core, and
commence
off at
and
with
a
short
loose when
springing
A from the right-hand
in Series and
the next
beginning
coil,
at B and winding from left to right,
observingthe same
off the opposite
precautionsas in the firstcoil,
finishing
end at H.
Next, wind the cores for the lower polepiece,
and finishing
commencing each at c and D respectively,
F
i.
winding on
in Shunt.
If the
fields
are
to
the two ends E and F will now
series,
terminal binding-screws,
and the two
brushes
the two
c to D
by
Fig.64.
two
ends
screw
If the
E
and
; whilst A
will be
be connected
in
be led to the two
ends
H
and
i
to
coupled to B, and
connectors, as shown by full lines in
fields are to be connected in shunt,the
F will be connected
togetherto form
a
coil from
continuous
DYNAMO.
GRAMME
THE
H
to
These
I.
59
ends
two
only will
be connected to the brushes,and from the brashes two
The dotted
of wire will go to each terminal
short pieces
lines in
Fig. 64 show this
ends
finishing
the two
clearly.When
more
of the left-hand coils are
to the
connected
ends of the rightterminals A, A, and the two finishing
hand coils are connected to the brushes B, B, the circuit
two
only be completed through the external circuit in
But
series with the coils and joining the terminals.
when the two ends of the left-hand coils are coupled
direct,as shown at c, and the brushes are connected
shown
the
with the terminals,
as
by the dotted lines,
and when
the
is shunted through the coils,
current
is running the cores
machine
are
always magnetised.
initial magnetism,
be charged with
must
The
cores
givenby a batterysending a current through the coils,
on
as explained
page 38.
can
The
dimensions
in the
mentioned
of the various
parts have
generalinstructions
which
cot
are
been
able
applic-
to several sizes of machines.
All parts are, however,
to the size of the castings,
and
proportionate
made
of these will also
the vendor
supplythe
various parts in
be incurred by
rough at a less cost than would
making patterns and having the parts cast to order. The
machines
sions
gives the dimenfollowinglist of Gramme
the
of various
partsand the output to be obtained.
TABLE
The
various
assembled.
or
three
The
coats
OF
GRAMME
parts of the
field magnet
DYNAMOS.
machine
now
may
coils should have
of varnish to cement
the wire
be
two
together,
DYNAMOS
6o
and
the
give
to
trial
best
the
little
where
the
others
built
are
side
The
horse-power
to
carry
following
needed
a
of
up
No.
of
by
has
the
4
has
the
table
to
bars
of
cogged
drive
or
in
help
Gramme
in
cated
indiis
sparking
commutator.
all
;
No.
16,
used
coils.
armature
the
determining
dynamos
the
The
plates.
of
the
is
there
no
armature
strands
justing
ad-
actual
terminals
laminated
current
will
the
by
position
little
and
cogged
two
the
at
solid
until
This
found.
brushes,
touch
1
rocker
current
the
at
No.
armature
side
full
brushes
Machine
is
In
appearance.
the
move
a
noise
finished
a
position
with
when
very
whole
brushes,
the
MOTORS.
ELECTRIC
AND
:
"
IV.
CHAPTER
THE
THE
Manchester
Messrs.
now
dynamo
Mather
Fig.
claims
construction
Siemens
and
and
63.
DYNAMO.
MANCHESTER
"
our
shown
at
of
Platt,
Manchester
attention.
and
Gramme
in
Fig. 65 (introduced by
Salford, Manchester)
Dynamo
In
usefulness
machines
complete.
point
it is
already
of
simplicity in
superior to the
described.
MANCHESTER
THE
When
happens
boltingthe
pole pieceor yoke
that whilst
of the upper
connection
is the
thus
not
are
.cores
DYNAMO.
with
of
cause
failures with
some
flanged]it frequently
parts togetherthe iron
is forced into electric
of the coils of
some
63
this alone
wire,and
this class of machine.
of the field is often
magneticintensity
thus carefully
marked
when cores
most
are
brought into
cloae connection with the polepieces. As the efficiency
of the machine
depends largelyupon its field magnets,
this pointshould not be neglected.
Figs. 67, 68, and 69 show how the flangesmay be
put on ; Fig.67 shows the core as in generaluse ; and
with a lightfilletcut in a lathe,
core
Fig.68 the same
The
difference in
:
Fig. 67.
Fig. 68.
Fig. 69.
Fig. 67. Magnet Core for Manchester
Dynamo.
68."
Core
with
Fillets
receive
to
Fig.
Flanges.
"
Fig. 69."
on
each
This
end.
iron collar
Core
core
washer
or
cold the collar will be
collars shrunk
field magnet
on
cores
Fitted
the
may
with
Flanges.
fit the hole in
must
when
Iron
a
wrought-
the collar is hot,and when
firmlyfixed. Fig. 69 shows the
and turned up bright. The
core
be wound
those of the Gramme
with wire in the
machine
; that
same
is,so
manner
as
to make
the top a north pole and the bottom a south
where the method
described in Chapter III.,
of
as
pole,as
connectingthe ends is also given.
The ring or the H-girderforms of either solid or
be easily
laminated armatures
chester
adapted to the Manmay
field. In some
of these machines Pacinotti cogged
others the Gramme
armatures
are
employed ; in some
the H form is convenient,
and
ring. For small armatures
will be most efficientwhen built up of laminated plates,
as
shown at Fig.10 (p.16). When
of the Gramme
armatures
or Pacinotti type are
used,it will be necessary to build
DYNAMOS
64
the commutator
up
described in the last chapterfor
as
machine,because
Gramme
MOTORS.
ELECTRIC
AND
have
must
we
a
commutator
a
with several sections to receive the ends of the armature
coils.
when
But
chosen,we
the
-girder form
also select the
must
of
is
armature
two-part
commutator
machine, and illustrated
in the Siemens
used
H
at
Figs.
33, 34, 35 (pages29 and 30).
The
the
are
massive
and
each
bearingson
wide
set
spindle. We
cast-iron
broad
side of the
enough apart
have
admit
to
therefore
bed-platecarries
and these
pole pieces,
a
long
enough
room
for
armature
a
rocker
arrangement and adjustablebrush-holders such as those
shown at Figs.GO, 61, 62 (pages 55 and 5G). The rocker
works
on
gun-metal sleeve fixed
a
of the brackets.
The
the inside of
one
of copper
of sheet copper.
soldered to thin strips
nections
Con-
wire gauze
between
as
brushes
to
them
be made
machine.
instructions for
The
necessary
and
Siemens
and all
winding the armature
particularsin the chapters on the
machines
Gramme
apply equally to
field magnets
and, indeed,to all others.
a
best made
the wires should
and
directed for the Gramme
other
are
machine
with
of the Manchester
type,
The
of Manchestei
followingtable givesparticulars
dynamos of various sizes.
LIST
All
the
laminated
OF
MANCHESTER
above
machines
cogged ring
TYPE
are
armatures.
DYNAMOS.
intended
That
to
have*
the last i*
THE
be
to
with
wound
side,
by
and
obtained
strands
in
together,
this
wire.
their
The
wound
compound
with
wound
shunt
with
machines
should
be
the
of
the
the
polished
dynamo,
in
connected
terminals
circuit,
it
will
shown
into
shunt
the
field
the
advisable
to
in
section
hard
at
slab
wood
D,
as
Fig.
shown.
on
also
cores
are
connected
in
circuit.
the
other
coils
being
outer
the
coils
more
the
smaller
with
or
wooden
is,
connecting
be
or
with
have
larger
and
for
mahogany
as
the
described,
above
arrangements
outer
the
the
to
fewer
that
wire,
winding
forty
"
armature,
armature
small
making
the
of
twisted
furnished
machines
magnets
sizes
two
with
the
field
two
on
them
have
large
Some
armatures.
with
the
and
bared,
are
machines
small
be
fastening
wound
more
winding
should
machines
often
armatures,
wire,
After
side
run
found
is
coarser
before
Large
bars.
wire
16
This
a
ends
65
No.
good.
the
soldered,
commutator
of
than
equally
way,
of
together.
on
are
and
Gramme
strands
winding
for
effects
DYNAMO.
two
wound
convenient
in
MANCHESTER
series
In
the
coils
magnet
In
armature.
machine
mount
with
a
on
the
66,
and
slab
top
screw
of
66
CHAPTER
THE
V.
SIMPLEX
DYNAMO.
Tui3
chapterwill describe the construction of a small
dynamo, or motor, made almost entirelyof wroughtiron forgings,
which can
be obtained from any smith or
made by the dynamo maker himself.
This
machine
generates
a
of 5 amperes
at a
capableof lighting
current
of 10
volts; and is about
two
used as a dynamo,
8 candle-powerlamps when
and, being shunt-wound,is also suitable for charging
used as a motor, running at
storage batteries. When
about 2,500 revolutions per minute, its power
will be
about
requiredwill be about
1*5h.-p. The current
pressure
5 amperes
drive this machine
To
be
at 15 volts.
about
i horse-powerwould
engine to develop this horse-power
would
have the followingdimensions :" Cylinder,
2 in.
bore, 2 in. stroke ; revolutions of flywheel, 200 per
minute ; boiler about 18 in. by 9 in. ; pressure, 20 Ibs.
on
required. An
square
The
inch.
armature
of
constructed
is of
soft
the
old
iron
Gramme
wires
ring type,
over-wound
with
About
l" Ib. of No. 20 to
iron wire will be required,
and also a circular
24 S.W.G.
wooden
mandrel, or former,of shape and dimensions
in Fig.70. This former should be turned from
shown
hard wood, with one of the flanges
or cheeks
removable,
that the iron ring when
completed may be slipped
so
insulated copper
off ; for the
with
may
on
a
be
same
the iron
the former should
purpose
layer of
held
wires.
in
smooth
place
wire,the
with
former
between the centres of
a
the
paper,
be covered
edges of which
sealing-wax. To
should
or
lathe,
a
wind
either be mounted
pin should
be driven
SIMPLEX
THE
into the centre
between
The
wooden
two
wire
of each
should
be
DYNAMO.
the former
end, and
supports,
wound
67
in
shown
as
mounted
Fig. 70.
the former
upon
in
even
with a coat of shellac varnish between every two
layers,
until the outside diameter of the ring is 2| in.;
layers,
the
thickness
The
whole
with
shellac
iron
cheek
then
then
armature
oven
the
be
about
should
armature
f in.
be coated
and
former
until the shellac melts and binds
wires
Mandrel
"
edgesof
coated with
the armature
for the
or
which
Former
for making
of Simplex Dynamo.
Core
of Armature
and the surface then
overlap,
shellac varnish. When
dry,the winding of
may be proceededwith. It is not essential
iron wire
continuous
number
of the
varnish,and
hot
a
will then
core
cool, the removable
together. When
should
be unscrewed, and
the armature
may
should
slipoff the former easily. The armature
be insulated by entirely
coveringit with silk tape,
Fig. 70.
the
the
surface
placed in
the
of
hank
must
of the
armature
coil ; the
coil to be
in
one
be built up of a
of hanks,provided that the lengthof wire contained
in each
or
is
core
may
and that each added
considerable,
To
pieceis properlyjoined to the wire last wound.
join the wires,twist the ends together,coil the joint
the layersof wire previouslywound, and coat
upon
with shellac varnish.
When
this is hard,file the joint
down
level with a smooth
file,
againvarnish,and proceed
with the winding.
is completelyoverwound
The armature
with three
layersof No. 20 s.w.o. double cotton-covered copper
wire divided into twenty sections or coils,
each section
DYNAMOS
68
ELECTRIC
AND
MOTORS.
having twenty-fourturns of wire, the whole weighing
about f Ib.
the
Before proceedingto wind
on
should be firmlyfixed to a bench
wire,the armature
table by passinga stripof hard wood
or
through the
interior and fasteningthe stripto the bench by screwing
in the manner
shown
in Fig.71. For the purpose
Fig. 71.
"
Clamp
for Armature
Core.
the winding and also to keep the armature
facilitating
properly balanced, it is best to divide the
with a pair of compasses
into a number
ot
armature
equal parts,and to treat each part separately.Thus, if
of
the
is divided
armature
will be
allotted to
into four parts, five sections
each part, and the coils can
be
arranged so as to fillthe
sufficient length of wire
around
spaces
to
allotted to
reach
the armature, with about one
one
etc.,having been cut off,
the hardwood
as
strip,
Fig. 72.
then carried
"
Method
shown
of
in
them.
A
twenty-fourtimes
foot
over
for
nections,
con-
end is fastened to
Fig.71,and the wire
is
winding Ring Armature.
the top of the armature
and threaded
throughthe inside,and pulledtight. This is repeated
over
three times ; the last inside turn rests upon
the
wires previously
at A, Fig.72.
wound, as represented
two
The
THE
SIMPLEX
DYKAMO.
69
the interior surface
alternately
upon
the preceding turns
and upon
until
been completed,when the wire is temporarily
to the hardwood
stripuntil the next
wire is thus wound
of the armature
eightturns
have
fastened
layeris commenced.
The
the
second
same
about
way,
five
The
armature.
with
a
or
and
purpose.
is commenced
the
and
ended
winding proceeds thus
six sections have
been
wound
be
A
mallet,and
pressedwith
coat
the wires
upon
a
wooden
of shellac varnish
on
in
until
outside wire should be beaten down
small wooden
surface should
same
section
the
flat
the inside
rod
for the
should
then
appliedto the wires,and when this becomes hard
in exactly the
the second layer is proceeded with
the first layer,with the exceptionthat
same
as
way
be
Fig.
the
wires
on
73." Wooden
the
arranged between
inner
those
Plug
surface
for
Armature.
of the
armature
already wound,
as
are
sented
repre-
Fig. 72, where the white circles show the
the black circles the second
first layer,and
layer.
in
layer is completed,the first layer
the second portionof the armature
be comon
menced,
may
two
and when
layershave been wound
upon
be wound
half of the armature, the third layer may
in exactlythe same
as the firstlayer.
on
way
After this third layeris completed,the ends of the
sections may
be permanently coupled up by cleaning,
and solderingthe adjacent ends of the sections
twisting,
the finishing
end of one
section being
together,
connected to the commencing end of the next section,
as
should then
shown at B, Fig. 72. The whole armature
hardwood
A
be coated with shellac varnish.
plug
When
this second
SIMPLEX
THE
over
the
spindleand
stringover
layer of
which
DYNAMO.
screwed
the
to the
71
centre
completes the
screws
A
plug.
ture,
arma-
representedin Fig.75.
The field magnet is of wrought iron,of shape and
dimensions
shown, and consists of the two pole pieces
will
(Fig.76) and the yoke (Fig.77). Two coil flanges
also be required. The
two
pole pieces are fitted so
that
with
the
a
is thus
revolves
armature
clearance
of about
in
-^ in.
the
space
They
are
between
fixed to
the
of two -^ in. screws
The
or rivets.
yoke by means
coil flangesare of hard wood, zinc,or sheet brass,and
are
slippedover the magnet core and held in placeby
the wire.
Before fixingthe pole pieces,
the magnet
should
be
wound
Fig. 75."
with
Armature
about
of
3 Ibs. of
Simplex Dynamo
No.
22
s.w.o.
complete.
singlecotton-covered copper wire. The yoke is first
covered with a layer of paper, and the wire is then
until the entire space is
it in even
wound
layers,
upon
is applied to the
when
a coat of shellac varnish
filled,
wire,and the pole piecesand bed-plateare fixed permanently
to the magnet by suitable screws.
Cast iron may
it has a lower
sectional
area
be used
for the field magnet, but
permeabilitythan
must
be increased.
wrought
Therefore
iron
make
as
the
the
cast-iron field magnet 1 J in. instead of
Wire
with
of the
same
| in. in thickness.
thickness (22 s.w.o.)
may be used as
of itwill be required.
thewrought-iron
core, but more
is also of wrought iron,
The bed-plate
and is shown
in Fig.79. Through it are drilled three -^ in. countersunk
holes for wood
screws, four -^ in. tapped holes for
and three ^ in. clearance
holding down the bearings,
DYNAMOS
72
ELECTRIC
AND
MOTORS.
holes for
or
plate
fixingthe bed-plateto the magnet. The bedis fixed to the yoke by means
of two Ts"in. screws
which also fix the lower pole piece,and by
rivets,
Fig. 76." Pole Piece of Simplex Dynamo.
a
third
The
underneath
screw
the
bearings(Fig.80)
yoke,as
made
are
Fig. 77." Simplex Dynamo
consists of
carry
shown
of
Yoke
the
Fig.77.
and each
brass,
for
uprightpiecedrilled with
and
armature
spindle,and
an
in
Magnet.
a
\ in. hole
a
to
base-plate
Fig. 78." Coil Flange.
plate
soldered to the uprightpiece and fixed to the bedOne of the bearingsis also
by two fV in. screws.
drilled with
a
small
in
the
shown
in
hole
as
fixingthe brush-holder,
upright piece fof
Fig.80.
The
"bout
two
DYNAMO.
SIMPLEX
THE
(Fig.81) is made of sheet brass,
hole in centre,and
drilled with a i-in.
\ in. thick,
brush-holder
holes at each end to take wood
Fig.
79." Bud-Plate
at
copper
one
secure
Simplex Dynamo.
of
piecesof ebonite or boxwood.
and carry the brushes,
which are
or
which
screws,
small
brass
73
These
of thin sheet
made
end drilled with two
taking round-headed brass screws,
fixes the brush to the insulating
block
for
Fig, 80." Bearings
late
to insu-
serve
holes,
small
one
of which
while the othei
of Armature.
fixes to the brush the flexible connectingwire from
The
terminal.
screws
holding the brushes must
be
A
metallic
in
holders,so
arc
that the brushes
until the
Then
commutator.
as
screw,
with
slot is also made
small
small
contact
shown
in
correct
the
as
may
brush-holder
shown
positionis
the brush-holder
Fig.82, which
brush-
through a
found
is fixed
not
itself.
in the
be moved
the
by
on
a
representsthe
the
small
plete
com-
machine.
The
be of almost any of the well-known
Figs.14 to 20 (pp.18 to 20),and may either be
terminals
types, as
can
DYNAMOS
74
fixed upon a hardwood
in Fig.82, or
as shown
machine.
In
and
coil,
brushes
ELECTRIC
AND
either
board
upon
case
a
MOTORS.
placedupon the magnets,
board carrying
the whole
the wires
from
connected,as shown
are
the magnet,
in
Fig.82.
Fig. 81." Brush-Holder.
The
pulleymay be of brass,from \\ in. to 2 in. in
diameter,about 1 in. on the face,and fixed to the
spindleeither by a screw or a key. The belt should be
about 1 in. in width,and not more
of leather,
than \ in.
Fig.82.
"
thick.
The
Simplex Dynamo
machine
coat of paintand then
may
be
complete.
finished by giving it
a
varnishing.
the armature
To start the dynamo, run
at from
2,500 to 3,000 revolutions per minute,and if the machine
is properly constructed it will excite itself after the
fields have been initially
magnetised by the current
SIMPLEX
THE
from
run
as
about
motor,
a
which
is
the
north
to
will
the
brush,
one
be
75
machine
It
required.
of
pole
its
wanted
to
acid
cells
is immaterial
the
be
must
end
finishing
The
magnet.
coil
field-magnet
and
is
chromic
eight
or
south
or
of
end
commencing
the
seven
cells
accumulator
or
If
battery.
small
a
DYNAMO.
the
to
nected
con-
other
brush.
Below
for
dynamo
of
pressure
six
this
be
10
minute.
being
also
the
latter
if
cells
wound
with
and
amperes,
Armature,
covered
each
in
in. ;
inside
outside
in. thick.
pole piece,
thick.
cotton-covered
running
in.
at
300
diameter,
wide
would
be
2,500
revolutions.
with
revolutions
a
pulley
required
about
the
of
Ib.
No.
18
by
a
of
\ in.
S.W.G.
engine
an
2i in. diameter
armature
in.
"
about
With
and
in. ;
3
thickness
bobbin,
min.,
spindle,
2| in. wide
in. ;
11
total
segments,
iron
wire.
per
on
of
cotton-
disc,
of
and
sections,
Diameter
about
copper
wires,
layer"
per
coil, 4"
Flanges
wound
turns
wrought
tions
revolu-
double
commutator
field
\ in.
iron
The
diameter,
twenty
thickness
of
in.
a
charging
2,500
3
B.W.G.
320.
rectangular
about
speed
into
of
in. ;
Length
Bobbin
single
18
of
magnet
If
16
eight
diameter
for
at
required.
are
annealed
No.
armature,
on
diameter,
Field
\\
wire
lamps,
2" in. wide,
divided
with
layers,
two
of
turns
of
wire,
copper
shunt-wound
a
suitable
the
of
layers
two
of
10-candle-power
| in. thick, constructed
core
|
volts,
15
will
per
four
lighting
accumulator
current
dimensions
given
are
flywheel
of
by \\ in.
spindle
to
get
CHAPTER
CALCULATING
THE
VI.
SIZE
AND
SMALL
WE
with
commence
parts
is
wire
placed between
OF
M
IEB
FOB
DYNAMOS.
the
subordinated
are
AMOUNT
armature, because
to
it.
When
a
all other
loop of
copper
the
poles of a magnet in such
the lines of magnetism supposed
to vary
a
manner
as
to be passingthrough it,an electro-motive
force is set
all dynamoup in the loop. This principlegoverns
The loop of wire,multipliedmany
electric machines.
times and wound
of iron,is named
the
over
a
core
armature, and the magnet correspondsto the field of
the
machine.
other
things,the length of wire on the
determines the voltage; and in small machines
carryingcapacityof this wire determines the
Amongst
armature
the
safe
current
are
by
determined
The
'
obtainable.
armatures
.
one
of three
size and
form
"
armature
an
three
the shuttle,
the ring,and
viz.,
types admit
of several
coil of wire
the shuttle type, one
the two
channel between
cheeks,and
In
the coil are
of
the desired output of the machine.
in use
be classed under
most
may
types
These
drum.
The
attached
to two
halves of
a
variations.
is wound
the
the
two
in the
ends
of
ring.
commutator
wire coils each
six,eight,or more
ringtype, some
of the same
length are wound in sections over the ring,
the ends of each coil being brought out and soldered to
In the
as
the
many
bars
on
the commutator
armature, the
commencing
end of
type the coils of wire
altogetherover the armature, not
same
ring form, but
manner.
there
are
finishingend of one coil
the next being soldered to
In the drum
in the
as
the
coils
are
wound
through
we
coils
and
one
on
the
bar.
in sections
the
connected
ring,as
in the
WIRE
CALCULATING
shuttle form
The
these
get
soon
machine
hot
so
and
as
endanger
77
easilywound
is confined to small machines.
speciallyapplies to
This
DYNAMOS.
is most
of armature
connected,but its use
and
SMALL
FOR
solid shuttle armatures, as
to reduce the output of the
the
insulation
the
of
wire.
is,built up of thin
modified. It
iron plates this tendency is considerably
is the type of armature
usuallyemployed in model
dynamos, with fields of the simplehorseshoe or Siemens
type (SeeChap. II.).
The
is preferableto the
ring-type of armature
shuttle for largerdynamos, but is very difficult to
wind
when
small,since the space through which to
and
more
pass the spoolcarryingthe wire becomes
contracted with each layer and section of wire
more
wound.
It is generallyused in dynamos with fields of
the Gramme, Manchester,Brush, Kapp, and Simplex
the shuttle is laminated
When
that
"
"
types.
The
than the
the
type of
drum
ring,since
is
armature
easilywound
more
all the wire is wound
the
over
ture
arma-
outside in sections ; but it is difficultto connect, as
is apt to lose sight of the exact order in
winder
which
the
of wire
ends
coil is marked
with
are
to
be connected.
different tint
a
or
If each
colour of cotton
or
thread,this trouble will be much mitigated.
The voltageobtainable from a shuttle dynamo is
roughlydetermined by the length of insulated copper
silk
wire coiled
governs
a
the
on
length that
given size.
wire
its armature.
model
diameter
be got on
dynamos, each
can
an
of the wire
armature
yard
of
of active
will
give about 1 volt (all
other conditions being favourable)when
moving at a
circumferential velocityof 1,250 ft. per minute.
This
last statement
requiressome
explanationto make it
clear.
Active wire is that portion of each coil of
wire which
is employed in cuttingthrough the lines
of magnetic force given out by the field-magnets.
On
a
on
drum
coils
over
the
In
The
armature
armature, all the wire except the parts of the
the ends
of the drum
is active wire.
The
WIRE
CALCULATING
SMALL
FOR
DYNAMOS.
Carryingcapacityin amperes is calculated
2,000 amperes
capacityof
carry
per
the wire
without
the insulation
the current
coils and
square
inch.
is the maximum
heatingto such
seriously.In a
in the outer
be of
the former.
The
safe
carrying
it will
extent
affect
to
as
series shuttle
dynamo,
through armature
therefore the wire
diameter
a
an
about
at
current
circuit passes-
coils ;
field-magnet
latter should
The
70
about
equal to
that
accompanying tables will serve
suitable wire 'for the armature
guide to selecting
field-magnetcoils. The following table deals
wires on the Standard Wire Gauge.
PROPERTIES
The
resistances
conductivity
copper
OF
S.W.Q.
given above
at
a
COPPER
are
the
on
on
as
a
and
with
WIRES.
for 100
per
temperature of about
cent
65"
F.
DYNAMOS
8o
Under
ELECTRIC
AND
MOTORS.
the heading "No.
of turns per inch" will be seen
three divisions" A, B, and c.
Of these B and c refer
have specialthin
to wires which, in the small sizes,
silk and
coveringsof
insulation is reckoned
double
cotton
to 20
at the rate of 12 mils
in sizes below
coveringis
the average
Under
respectively.
cotton
No. 16.
about
=
Above
^TQ
A
^n- "^
this size
mils,varyingfrom
14
the
10
mils,however.
The
output of
a
dynamo
that
"
is,its
electrical
is
This is obtained
generallycalculated in watts.
by multiplyingthe total voltage by the amperes.
But as this method
of stating
a dynamo's output admits
the volts
it is best to specify
of uncertain interpretation,
and amperes
separately.
power
"
In
in the
varies inversely
the resistance
as
therefore,
fields,
circuit,
being less when the resistance is high
of the
than
series machine
the field magnet coils are connected
in series with the outer circuit. The magnetism
a
when
it is low.
In
a
shunt-wound
machine
the
in a shunt with the
field magnet coils are connected
circuit. There are, therefore,
two
outer
paths open to
current : one
the armature
through the field magnet
and
coils,
the other
through
resistance in the outer
the
circuit
outer
being
circuit.
lower
than
The
that
current
of the field magnet coils,
more
goes by way of
but when the
the outer circuit than goes round the coils,
resistance
of
the
outer
circuit
is
increased,more
by way of the coils,and this raises the
of the fields. The effectof this is to
magneticintensity
raise the voltageof the current,and enable it to overcome
In a compound-wound
resistance.
the extra
the field magnet coils are partlyof thick wire
machine
and outer circuit,
connected in series with the armature
while a small wire of high resistance is connected in
be made
This form of machine
shunt.
to give
may
minals.
constant
almost
a
potentialdifference at the tercurrent
goes
styleof winding has its own
adaptingit to the kind of work
Each
tages,
peculiaradvanto be done by the
CALCULATING
machine.
A
WIRE
shunt-wound
dynamo
; for
certain extent
SMALL
FOR
DYNAMOS.
becomes
81
lating
self-regu-
the
lamps are switched
off the resistance in the outer or lamp circuitbecomes
is shunted through the field
current
greater,and more
coils,
therebygeneratinga highervoltageto overcome
the
while a compound-wound
increased resistance,
to a stillgreater extent.
dynamo is self-regulating
A rough rule for shunt-wound
machines
with about
is as follows :" Let the resistance
90 per cent, efficiency
be represented
of the armature
by 1, that of the outer
circuit by 20,then that of the field magnet circuit should
to
a
as
that is to say, the outer circuit should have a
resistance twenty times that of the armature, and the
fieldmagnet circuit should have a resistancefour hundred
be 400
"
times that of the armature.
coils should
field magnet
In
have
thirds that of the armature
series
a
a
coil. In
machine, the
resistance about
a
compound machine,
the resistance of the series coils should be the
In small machines
that of the armature.
have
machine"
be
to
to
modified.
considerably
give6
at 50 volts"
amperes
two-
as
same
these tions
proporIn a 300-watt
the field magnet
be reduced to 200 instead of 400, and
resistance may
resistance rapidlydiminishes
this proportionate
with
each small reduction
the
smallest
resistance of
machine,until
workable
dynamo will only admit of the
the field magnet coils being some
twelve or
fifteen times
that of the armature
impossibleto
small
in the size of the
machines
determine
; for
coil. It is almost
exactlythe output
apart from
the
of such
variations
from
rules,others are likelyto crop up through
of iron employed,hardness
differences in the qualities
loose winding,insulation,
of wire,irregular
or
tions,
connecsize,form and make of commutator, and quality,
and pressure of brushes,
etc.
position,
'of the
Properlydesigned castingsfor the carcase
dynamo usuallyhave ample space allowed for winding
theoretical
sufficient wire
machine.
or
to
If the
cast, and
suit
carcase
the
electrical output of the
of the machine has to be forged
the rings or
punchings for the
armature
DYNAMOS
82
made
to
ELECTRIC
AND
order, proper
MOTORS.
be allowed
must
space
for the
to the tables given on pages
By referring
79, the spa" e likelyto be occupiedby the wire
found under the heading No. of turns per inch
is,so many turns of wire of a given gauge will
wire.
"
by side in
armature
1 in. of
be
must
wire without
and
sides of the
of the
edge
tunnel
One
are
cheeks.
ring or
will be
"
lie side
shuttle
a
drum
that
"
required
The
space
armature
it is to work
in which
^a in- between
should be sufficient to leave
the sides after three
in
take the
to
the
bulging beyond
the outer
on.
channel
large enough
between
the
The
space.
78 and
the wire and
layersof the wire have been wound
the best,but
layeris theoretically
three
layers
admissible.
length of the field magnet
The
three
or
three
and
provisionshould
a
half
be made
increase the diameter
times
three times.
The
space
wound
and
find the
core
be about
may
diameter,and
enough wire to
their
admit
to
of the
cores
of
from
two
and
a
half to
occupiedby the wire may
be ascertained by estimatingits length and weight or
lengthTper pound, notinghow many turns to the inch
Estimate
the probable diameter
of the
it will run.
core,
to be
mean
between
this and
the
bare core, then multiplythis by the factor 3'14,and so
of turns and the space likely
ascertain the number
to be
occupied by the wire. Heavy yokes and pole pieces
because dynamos work best when
are
always admissible,
the iron in them
is in
of that needed
excess
to maintain
magnetic saturation. It is also advisable to have a
than will be actuallyneeded to furnish
largercarcase
the requiredoutput, since machines may always be safely
worked
to lightfewer lamps than they were
designed
for ; but it is not safe to work them at a higherspeed
to procure a larger
output.
Before the planfor winding the armature can be drawn
up, the resistance of the outer circuit namely,the work
first be ascertained.
must
to be done by the machine
If this resistance is too low,a shunt machine will fail
to supply the requiredcurrent, and a series machine
"
"
WIRE
CALCULATING
SMALL
FOR
DYNAMOS.
83
high, no current will be
obtained from a series machine,and that from a shunt
will be diminished.
machine
In largemachines,carefully
of 1 volt per foot of effective
wound, an efficiency
wire on
the armature
moving at a circumferential
of 1,250 feet per minute has been attained,
but,
velocity
has been stated,1 volt per yard is what
be
as
may
Although the voltageof
expectedfrom small machines.
the speed of
be increased by increasing
a machine
may
its armature, it is not always safe to do so, because an
increased voltagewill send more
round the field
current
and this may dangerouslyheat them. In a
magnet coils,
series machine,all the current passingthroughthe outer
will burn
its coils.
If too
circuit also traverses
the field magnet coils. In
the bulk
of all its current
a
pound
com-
machine,
passes
coils
the
series
and
fraction
it
of
through
only a
through
the shunt coils. In a shunt machine,only a fraction of
the current passes throughthe field magnet coils. Consequently,
fields of
the
magnetised when
fields of the
magnetised.
the brushes
the
a
should
outer
series machine
are
circuit is open,
and
machine
shunt
When
the
be
is
given a
the
then" most
highly
at a higherspeed,
forward
lead,to
are
machine
not
run
more
compensate for increased distortion of the field.
The
wires for
indiarubber
dynamos
may
be
protectedby using
gutta-perchadissolved either in benzole
in naphtha. This solution will make
elastic
or
an
insulatingvarnish,but it is liable to injuryfrom oil,
renders the varnish soft and sticky. Shellac
which
varnish
is
or
one
of the
best
for the
purpose.
This
is
by digestingshellac in methylatedspirit,
kept in
a stopperedglassjar in a warm
placefor twelve hours.
Green or red sealing-wax
digestedin warm
methylated
i
s
also
used
varnish.
as an
spirit
insulating
made
Few
on
an
made
one
persons
can
get the calculated
armature, although a
for
hand
slack
winding.
and let the wire
other,drawing
it
more
run
or
amount
full allowance
To
take
an
of wire
has
been
armature
of
through the fingers
less tight,
winding as
in
the
one
DYNAMOS
84
would
wind
up
ELECTRIC
AND
ball of
a
MOTORS.
string,sometimes
working
ture
evenly,sometimes not,will not do. To wind an armaif of either the drum
or
especially
ring
properly,
type, is work for two people. Even a shuttle armature
should not be attempted by one
person unless he is an
experiencedwinder ; and even then he will wish he had
three hands.
After the wire has been
and
properlyparaffin-waxed
on
as
drained, it should be wound
tightas possible,
without, of course, breaking it. Any wire that is not
should
or is in the least respect faulty
straight,
perfectly
of a small wooden
be driven well into placeby means
hammer
or by a small wooden
stick,
neatlysquaredand
at the end, and used as a punch. Every wire
smoothed
should be made to go as .near to its neighbouras possible.
that winding an armature
It will be seen
properlyis no
lightwork.
is
one
Cheap wire is very bad, for two reasons"
low percentage
that the wire itself has a comparatively
of copper, and wire should not be used that has less than
97 per cent, as it givesthe armature
a needlessly
high
resistance.
The
other
thick cotton
for its
is that
covering,and
cheap wire has bad,
occupies
consequently
of trouble is thick,
wastefully.Another source
clumsy taping. There should be justenough to ensure
and no more.
Bad tapingtakes up a
perfectinsulation,
and space is preciousto a winder
of
lot of room,
Remember
armatures.
this,and do not be .afraidof
usingthe wooden hammer.
the length of
In treatingthe subjectof calculating
space
wire for armatures, two types only will be taken
viz.,
shuttle armature
the Siemens H-girder,
or
(Figs.83 and
"
84) and the cog-ringarmature
(Figs.85
and
86),as
doubtedly
un-
they are the best types of armatures for smalland
sized dynamos ; the former for the very small sizes,
the latter for somewhat
largerones.
They are also the
easiest kinds to wind
suitable for amateur
As
an
and correct,and
workers.
it would be
illustration,
are
therefore very
best to take
a
sample
WIRE
CALCULATING
SMALL
FOR
DYNAMOS.
85
armature, fix upon a certain gauge of wire,and follow up
the working to get at the weight and length of wire
required
; by this
example at hand to
the
means
from
work
reader
in
cases
will
have
an
of armatures
of
other sizes.
The
first example will be
laminated shuttle
a
2" in. long,l" in. in diameter
83
(Figs.
ture,
arma-
and
84),
,*"_.
{.-
"
Fig. 83." Section
of Shuttle
havingthe
web flush with the ends.
size would
probablyhave wire
Fig. 84." Side View
Armature.
An
spaces
of Shuttle
armature
of this
I in. wide,and by
Armature.
making the segment of the circular area form a rectangle
of equalarea, as shown by the dotted lines in Fig.83, the
wire space would
be " in. deep,leavingf in. for the
thickness of the web.
In calculating
shuttle armatures
the shaft need not be taken into consideration,
as itdoes
not
affect the
amount
of wire
that will go
into the
channels,though it makes the winding at the ends
which
be helped; the slightextra
cannot
irregular,
WIRE
CALCULATING
wire
of
wire
or
\ lb.,
ehould
this
for
the
shaft did not
pound,
so
be
would
course,
ends,much
windingwould
the
to
armature
say J Ib. Of
the
armature
back from
the
yds.
80
goes
DYNAMOS.
SMALL
FOR
less wire
be neater
7
amount
yds.
it will be observed
solid,with
be
the
87
and
can
more
the
web
over
that
set
be got on, also
compact if the
through the web.
For the other example a laminated
ture
cog-ringarmawill be taken, 5 in. in diameter,3 in. deep,having
twelve cogs ; wire spaces f in. wide and | in. deep,with
run
~VT
Fig. 86." Side View
the
core
of the armature
of
Cog-ring Armature.
| in. thick at the wire spaces
and " in. thick at the cogs. (SeeFigs.85 and 86.) This
it is proposedto wind with No. 12 S.W.G. cottonarmature
operationis very similar to
the example above,one whole coil beingcalculated first.
A section of the armature
core
through a wire space
off the f in.,
be drawn as in Fig.85 ; then setting
must
the depth of the wire space all round,the longestmean
coil is found as a rectangle,
as shown
by dotted lines.
length of all the
Proceeding as before,the mean
coils is found ; thus the shortest (2 X 3) + (2 X f)
6 i in. ; and the longest
(.2X 3J) + (2 X U)
9* ;
coil will be 8| in. long. The
then the mean
wire
covered wire.
=
The
mode
of
=
DYNAMOS
88
tables
show
(p. 78)
coils, three
As
be
coils
the
armature
S.W.G.
cotton-covered
between
A
coil
rectangles
(2
+
in.) +
2"
X
(2
the
coil, we
mean
coil
two,
be
coil
to
the
coil
;
length
of
the
sides
of
the
coils.
the
2
of
If
the
=
in.)
these.
| in.).
in. +
(2J
+
3"
X
sum
:
half
coil
(2
=
(3J in.
2
12
pound
shortest
written
=
the
No.
shortest
85),
talking
and
yds.
half
=
may
longest
the
combining
coil
mean
for
yds.
and
longest
f in.) j longest
X
wire
adjacent
(p.
will
separate
41
mean
two
any
twelve
in
enough.
be
the
example
shortest
Similarly,
will
coils
say
=
five
length
total
of
in
so
for
fifteen
are
S.W.G.
;
room
the
8'8
runs
the
(2
in.) ;
If
X
the
Now,
together
first
12
X
Ib.
be
length
determine
forming
the
Taking
there
123f
4J
to
way
add
to
and
as
total
wire
Ib.
4J
be
long,
12
inch
make
in.
but
;
No.
linear
will
is 8J
of
will
which
the
will
simple
is
there
armature
whole
so
in.
in-
123|
=
coils
the
to
coil
MOTORS.
eight
go
deep,
mean
8"
on
f
X
layers
the
X
15
in.
f
space
all.
that
wire
cotton-covered
the
ELECTRIC
AND
in.)
:
and
for
sum
the
get
in.
${(2j
+
f in.) +
(3j
in.
+
If
in.)}
*
which
is
equal
multiplier
and
| in.
in.
3J
in
and
+
+
li
in.
the
=
to
divisor
+
If
second
mean
coil
mean
=
in.
;
of
fraction,
=
mean
6| in.
+
we
6
=
example,
by
cancelling
have
left, 2J
and
3
1J in.
in
in.
=
-f 1^
in
+
in.
f
8| in.
=
in.
the
+
7J in.;
-f- 3f
in.
VII.
CHAPTER
AILMENTS
OF
AND
CUHES.
common
to
CAUSES
To
localise the
faults
require a battery of
and
three
or
dynamos,
cells of
four
type, a galvanometer
constant
THEIR
MACHINES,
DYNAMO-ELECTRIC
SMALL
or
current
[shall
we
a
strong
detector,
and a magby electric-bell fitters,
netised
To
needle or
a
repair the
pocket compass.
soft solder,
shall need a soldering-iron,
some
faults we
resin to solder faultyjoints; a pair of stout
and some
pliers,a screwdriver,small spanners to fit the nuts
soft cotton
the machine, and some
or
tape, or both,
on
well soaked in melted paraffin
wax.
is the singlefluid
The best battery for the purpose
bichromate
battery that is,a batterycomposed of jars
bottles of glass or stoneware, each
wide-mouthed
or
gamated
holding a pint. Each jar contains a plate of amaltwo
zinc between
plates of carbon, and is
charged with a liquidcomposed of 3 ozs. bichromate of
potash dissolved in a pint of water, and 3 ozs. of
be allowed to cool
sulphuricacid. This liquidmust
before the zinc plateis placed in it.
be connected to the
cell must
The zinc plate in one
carbon platein the next cell by a stout copper wire,say
such
those
as
used
"
No.
16
s.w.a,
so
the row,
the row.
as
and
to
one
About
all
and
leave
one
carbon
the
cells must
be
thus
zinc
plate free at one
plate free at the other
ft. of No.
No.
nected
con-
end of
end
of
wire,
attached to these end platesby suitable binding-screws,
the batterywith the galvanometer
will serve
to connect
the machine.
A steel darning-needle,
and
magnetised
by rubbing it on a permanent magnet, and suspended by
witt-serve
to hang horizontally,
a piece of cotton
as
a
2
18
or
20 S.W.G.
DYNAMOS
QO
substitute for
the
pocket compass.
a
faults
following
If the
current
ELECTRIC
AND
MOTORS.
With
this apparatus
be localised.
may
of the magnets are not
will be generated in the armature
cores
magnetised,no
coil. If
one
of the field magnet coils of an overtype or undertype
machine
is wound
in the wrong
both pole
direction,
piecesmay
have
result will be
a
like magnetism,and the
obtained.
One
pole
to the other.
oppositepolarity
beingheld near the pole piecesof
an
machine,
of the
one
of them
needle,and
should
the other
same
negative
piece must
The
compass
have
needle
ordinarytwo-pole
attract the north pole
repelit. The machine
an
should
be tested in this way whilst the armature
is at
it is running. If the coils are
rest, and also when
wrongly connected,there
may
be
a
similar result.
If
the compass
needle does not indicate any magnetism,
be assumed
that the
or only a feeble magnetism,it may
polepiecesare
not
magnetised.
The whole of the armature
current in
a
series machine,
ployed
portionof it in a shunt machine, will be emin maintainingthe magnetism of the field; we
be careful so to convey it through the field-magnet
must
coils as to retain the polarityof the cores
induced
initially
by the batterycurrent.
series-wound
A
dynamo employed in depositing
metals from their solutions,
in charging accumuor
lators,
is liable to have its poles reversed by a back
the accumulator
cells.
current from the plating-vat
or
series dynamos are
For this reason
suitable for
not
The polarityof the core
such work.
is also reversed
when current is sent through its coils from a battery,
or
and
a
another
dynamo,
to
run
the machine
as
an
electricmotor.
Compound-wound machines are also liable to a reversal
of their magnetism from a similar cause, owing to a
current passingthrough the series coils. A
high reverse
machine
shunt-wound
can
only be reversed by such
when
its field-magnet
coils are
means
nected
wrongly conmachine
to a battery; therefore,
a shunt-wound
should always be used for chargingaccumulators
and
AILMENTS
for
SMALL
OF
MACHINES,
DYNAMO
This
work.
electro-depositing
altered
gi
polarityof
be detected
by the compass
field-magnetsmay
needle being held to them, and the original
magnetism
the
can
be
restored
by
the
means
adopted
at
first for
magnetisingthe cores.
which
also be named
Magnetism neutralised,
may
when
the
the magnetic poles,occurs
short-circuiting
polesare bridgedby a mass of iron,as when an underor an
type
overtype field is bolted direct to an iron bed-plate,
field is bridgedby an iron platesecured to the pole
the polar
air space is left between
an
pieces. When
extremities
of
a
horseshoe
magnet, the magnetic lines
supposed to stretch across from one
pole piece to the other,and are then in a position
coils. But
when
to
a
pass through the armature
the greater
pieceof iron bridgesthese polarextremities,
number
of the magnetic lines pass by way
of this
from
and so are diverted through the armature
bridge,
their useful path, and, as there are, therefore,
few
lines of force passing through the armature,
or
no
from the machine,
there will be a very faint current
of force may
or
none
be
at all.
field-magnetshave been short-circuited by
placinga guard of thick iron over the armature gap
The
of an
guard over the armature
overtype
space
dynamo should be of zinc or gun-metal; and if it is
to have a metal bed-platefor an
undertype
necessary
dynamo, brackets of gun-metal or of zinc should be
interposedbetween the magnet poles and the iron of
the bed-plate.
If the machine does not givea current or the desired
of the field have
though the magneticproperties
effect,
been tested as directed and found perfect,
leakageor
of the coils may be suspected.To detect
short-circuiting
this we
must
employ a battery and galvanometer,as
before explained.Leakage most frequently
takes place
The
between
the wire
magnets
or
on
the
of the coils and
the armature.
castingshave
not
the iron of the field
Perhaps^therough
been made
smooth.
corners
Perhaps
DYNAMOS
92
the iron has
been
not
MOTORS.
ELECTRIC
AND
coated with
thick
sufficiently
a
layerof varnish,
paraffined
tape, or calico ; or the wire
has been pulledtightover
these rough or unprotected
parts, and
the
bringingbare
consequence,
insulation
has
copper into contact
the current takes
the iron instead of
and the result is
seen
been
with
a
diminished
a
bare iron.
short cut
going through all
in
through, thus
cut
by
As
way
the coil of
a
of
wire,
output from the
machine.
-
The
quently
frefollowing is a rough-and-readymeans
this fault. Disconnect
adopted for discovering
the ends of the field magnet
and connect
one
coils from
end of the coils to
one
their terminals,
terminal
of the
battery. Then take a long exploringwire and connect
and with the
to the oppositeterminal of the battery,
free end of this]
scrape the iron-work and metal- work of
the machine at several points. If any bare part of the
wire coil is touching the bare iron of the machine, a
brightspark will be seen to flash from the part of the
necting
machine
touched with the exploringwire. By disconeach
the two coils from each other and testing
the faulty one
be discovered.
The
separately,
may
be tested in a similar manner"
coils may
in
fact,they must be tested for leakageas well as those of
armature
however, in both cases to
advisable,
tery
placethe galvanometerin circuit by connectingthe batwire to the
and then to connect the exploring
to it,
galvanometer. If the needle moves, it shows that there
however small or largethis may be,but the
is a leakage,
rough test will only reveal a bad leakage.
Leakage of another form may occur between adjacent
and is due to the
turns or layersof wire in the same
coil,
such cause
from some
off of the insulation,
as
stripping
hammering the coils to get them in their proper places,
is overfrom pullingthem too tight. If a machine
driven,
or
is short-circuited,
the
if a series machine
or
insulatingcoveringmay get burnt off,and thus the
the fields.
It is
coils become
short-circuited.
This
fault
can
only be
discovered
by
means
of the
AILMENTS
SMALT.
OF
DYNAMO
MACHINES.
93
galvanometerin circuit with the battery. Each coil
the deflections of the
be placedin circuit separately,
must
galvanometerneedle noted,and these compared. Equal
and this
lengthsof wire should have equal resistances,
should be indicated by equal deflections of the galvanometer
much
farther
needle. If the needle swings over
coil is in circuit than when
when
one
same
length is tested,we
short-circuited
than
should
the
a
similar coil of the
expect that
may
coil to be
ance
somewhere, because it offers a less resist-
perfectcoil.
be unsoldered
coil of the armature
Each
the
from
bars
commutator
and
separatelyin comparison with the others. All
and the fault repairedby
faultycoils must be unwound
the bare spot.
cotton or tape over
winding paraffined
between the commutator
occurs
Leakage sometimes
bars and the spindle,
the sections of the comor between
mutator
between
the brush-holders and other
or
itself,
Any of these leakagesmay be
parts of the machine.
detected by the galvanometerand one or more
cells of
bars may be accidentally
the battery. The commutator
placedin contact with the spindleby usinglong screws.
attach one
To detect this fault,
batterywire to the
spindle and the other to the galvanometer, then
touch each bar with the free wire from the galvanometer
tested
watch
and
the
needle
when
moves
with
in contact
indications
the
the
bar
of the
needle.
is
touched,that
spindle.Any faultyscrew
a
If
bar is
must
withdrawn,and a shorter one used. If the bars are
connected by metal dust,or by expansionof
accidentally
the sections whilst heated,this fault may
be detected by
placingone wire from the batteryon one bar and the
wire from the galvanometeron the next bar. The coils
be disconnected from the bars whilst this is being
must
be
done.
from
Sometimes
the
machine.
the brush-holders
This
fault
may
are
be
not
insulated
detected
by
testingeach separatelywith the body of the machine
and then testingthe two
in circuit,
together. If all
should pass between
them and the
is right,
current
no
machine
or
between
the two
holders when
the brushes
AILMENTS
until the best effects
moved
needle,this
of the
MACHINES.
DYNAMO
SMALL
OF
tion
by the deflecfor the
position
noted
are
95
will be the best
brushes.
Sparking at the Brushes. The machine may run all
right,and give a fairlygood current for a short time,
ing
but there may be much
sparkingat the brushes,burnthem away
and burning pits in the commutator.
This shows defective construction or bad adjustment
of the brushes.
The
likely faults in construction
Coils of a varying length and resistance on the
are
:
"
the
armature, insufficient resistance in
coils,or
the
leakage
between
the
This
last defect may
be
coils. Perhaps these
of the machine.
carcase
field magnet
coils and
armature
found
by examining the armature
touch the iron occasionally,
and rub off the insulating
coating. This may be due to too much end-shake of the
armature
bearing,or to a loose
spindle,to a worn
to wobble.
bearingallowingthe armature
A small washer on the spindlewill correct too much
end-play,tighteningthe nuts will remedy a loose
be bushed
with
bearing must
bearing,but a worn
side-shake.
If leakage occurs, the worn
brass to cure
spot should
be
coated
with
varnish
between
the folds of the wire.
that too
much
work
is
mended
Armature
as
follows
Wire.
Such
"
"
the
described
wire
a
then
either Brunswick
and
bevel the two
the
wire
and
dip
itself
it in
with Brunswick
Sunning
it is in the
work
up
to
as
in
can
the
be
near
black
or
winding,bare
ends,tin the bevels,and
then
jointtogether;
solder
can
winding,bare
them together,
and
red
indicate
brushes
and clean the'two
ends,twist
paintthe jointover with
sealing-waxvarnish. If
well
the machine.
on
If it is outside the
:
in
Sparking may
being thrown
Sparking due to bad adjustment of
be cured by alteringtheir lead,as
previoussection (p.94).
Broken
worked
sweat
the
the
size of
possible,
relap the jointwith silk,
melted
paraffinwax, or paint it over
as
black.
Hot."
Some
of the best
designed and
DYNAMOS
96
ELECTRIC
AND
MOTORS.
constructed machines
will get too warm
after a
heavy work. The passage of an electriccurrent
on
the wire coils will always warm
them
day'srun
through
and
less,
or
more
of this rise of temperature is unavoidable.
When
the temperature rises considerably,
when
the field
as
much
magnet coils feel quitehot if touched by the hand, there
is
serious loss in
always a
hot wires offer more
wires.
resistance to the current
main
The
heating the wires,because
of this excessive
cause
than cool
heatingis
an
employment of wires too small to carry the current
properly; or, in other words, the machine is required
work than it is properlycapable of. The
to do more
remedy here is clear enough. But sometimes the heating
it may
of a machine is due to defective construction,
or
be due to leakage. Solid iron armatures, and laminated
which are not insulated,
armatures
may get unbearably
because
of
in
short
hot
cross
or
a
time,
eddy currents
of iron from end to end of
in the mass
circulating
the armature.
When
by
is
an
the laminations
are
substance
insulating
these
sufficient),
end
travel from
currents
to
end.
separatedfrom
(even a thin
are
broken
Machines
coat
each other
of varnish
up, and
with
cannot
solid
iron
will
laminations,
armatures, or with badly-insulated
get hot enough to melt the soft solder connections at
the
commutator
and
distort the commutator
sections.
machines
the
leakage across
brushes will also heat the coils injuriously.Shortseries machine
seriouslydamage it,
a
circuiting
may
by charringthe insulatingcoveringof the wires.
In
series and
These
are
compound
the
most
ailments
common
of
small
dynamos.
Others there are, but it will often be found
that these
are
wear
and
due
only to faultyworkmanship
to
tear.
be useful here to say
of receivingshocks
possibility
It may
or
a
few
from
words
as
to
the
dynamos. There
serious shock to a person handling a
be any
cannot
dynamo givinga current of low voltage. Neither can a
person receive a shock merelyby touchingthe machine
AILMENTS
with
insulated
form
to
link
a
in
electric
with
it
touching
thoroughly
complete
that
bearings
all
that
See
grip
the
be
adjusted
wearing
brushes
thus
part,
sometimes
the
the
tainty
uncer-
may
it
to
brushes
put
in
a
new
must
explained.
commutator
very
adjustment
the
have
to
necessary
brushes
brushes
before
as
on
out
with-
that,
and
The
frequent
good
a
remembered
and
bearing
is
be
oiled.
speed
commutator
brushes
the
good
best
part
cut
re-true
segment.
is
Keep
take
to
a
angle,
demand
requires
properly
enough
machine.
proper
When
and
also
the
of
them
commutator
and
are
machines.
maintain
must
away
will
clean
wide
is
It
the
keep
commutator.
to
you
dynamo
a
parts
bearings,
wears
to
an
even
touching
of
high-speed
thus
parts
to
Sparking
the
the
to
are
and
and
tightness.
addition
fast,
wearing
pulley,
the
all
driving-belt
the
on
of
part
of
act
mere
which
by
needed
and
undue
in
attention
general
to
the
unsafe
circuit.
a
The
when
knowing
it, because
with
then
is
unless
only,
hand
one
It
any
is
not
installation,
large
a
acquainted
of
similar
in
circuit
light
whole
does
body
with
or
97
a
circuit.
dynamos,
large
as
the
electrical
closed
a
with
meddle
because
ground,
the
from
machine
the
provided
hand,
one
MACHINES.
DYNAMO
SMALL
OF
of
the
of
the
grooves
the
furrowed
in
CHAPTER
SMALL
THE
to
no
ELECTRIC
little model
the
VIII.
MOTORS
shown
CASTINGS.
Fig. 87, if made according
followinginstructions,
requires no castingsand
at
lathe for its successful
Fig. 87.
within
WITHOUT
Simple Electric
"
the reach
of the
idea
younger
Motor
It is also
complete.
readers
of this book
using a few tools,and will
exercise a little ingenuityand
patience. The motor,
when
complete and judiciouslypainted with such
wick
simple colours as red sealing-waxvarnish and Brunsto say nothing of
black,looks very presentable,
the laws of electro-magnetism.
its use
in illustrating
For the field magnet get a piece of f in. round
and bend
wrought iron 4" in. long,as soft as possible,
who
have
construction.
an
it into the form
apart
on
of
of
a
horse-shoe,with
the inaide ; go
over
it with
a
the ends
} in.
file to take tha
MOTORS
ELECTRIC
then
and
roughnessoff,
with
one
square
and
wind
the other.
three
from
over,
when
it round
will
a
do
"
true
long stripof
and
and
paper
paste it well,
are
about
go
Side
does
of the
the end
not
Elevation
a
coat
of Brunswick
Magnet
of Field
copper
paper
cover,
about
with
6 in. long ; wind
a
half
the wire
and
between
we
Block.
No. 28
short
S.W.G.
of
the
hitch,leaving
on
reachingthe other end,just within
of the paper;
then, still winding the same
back over
the first coils,
but be careful that
does
does not slip,
and that the second row
until
black.
requireany bobbins, so
winding it with some
wire.
Begin just
straighton
silk-covered
on
dry give it
magnet
Fig. 88."
even
99
all over,
except within i in.
all
the ends ; paste the outside of the paper
and go over
it with the fingers
to get it even
;
this is
edge
Cut
ends
the horse-shoe until there
thicknesses
Thin
can
the two
file up
i-in.-wide newspaper
"
CASTINGS.
WITHOUT
close and
the
way,
edge
go
the wire
not
sink
the first.
going back about \ in. or so, fix the end
by giving two or three turns on the oppositeleg of
that may
be conthe magnet or by any other way
venient,
and give the whole magnet another coat of
After
DYNAMOS
ioo
ELECTRIC
AND
MOTORS.
dry (itdoes not take
long),and go ahead again,alwaysapplyinga fresh coat
of varnish when an end is reached.
By taking care in
black,
turning,and repeatingthe coats of Brunswick
all danger of slippingwill be avoided.
the outside
The wire coils will not lie close together
on
of the bent part of the iron core.
Keep them close
Brunswick
black;
Plan
Fig. 89."
on
the
of Field
Magnet
make
however,and
inside,
and
them
Block.
radiate
of appearance
; winding round
will not interfere with the
in this way
for the
part
let this get
sake
the
When
coils laid
winding
measure
has
about
been
nicely
the bent
working.
continued
till the
| in. in diameter
all over,
finish off at the
oppositeend from which you began
by tying a piece of thread close up to the finish,
Wind
the
leaving another 6-in. length of wire.
thread in different directions,
and fasten it off with a
See
knot.
and
that
the
ends
of
bright.
(See Figs.88, 89,
For
the
armature
wrought iron, Ifi in.
take
the
and
iron
core
flat
90.)
small
piece
long, \ in. thick, or
a
are
of
a
soft
little
MOTORS
ELECTRIC
CASTINGS.
WITHOUT
101
thicker,and f in. wide ; file it smooth all over, and
take off all sharp edges. Get a short stripof paper,
f in. wide,and paste it Touri,dthe exact middle of the
iron
until
Give
the
it
there
a
paper
thicknesses
thwfe'-'Otfour
are
coat
Wack.
of Brunswick
and
on.
let
dry.
Now
begin to
wind
silk-coveredcopper
the
armature,usingNo.
wire.
Take
of Field
Elevation
Fig. 90." Front
great
the armature, turningbackwards
the field magnet, giving each
wind
black,and
will accommodate.
on
The
much
as
more
and
and
Clock.
forwards
layer a
wire
in winding
care
Magnet
36 s.w.o
coat
as
neatlythe
as
with
of Brunswick
the armature
work
is done
will be got on, and the better will be
the results ; finish off in the middle, and leave tags
at each end about 2 in. long. See that the coils are
the
more
not more
wire
than
" in. across
in
front,or
the magnet will
what
is meant.
Fig. 91 (p.102) will show
While winding the armature,it may be tried in different
positionsagainstthe magnet, to see that the coils are
quite clear of other parts, for if they do not touch
is againstthe magnet, it may
while the armature
be
that they will be all rightafterwards.
assumed
rub them.
MOTORS
ELECTRIC
off
cut
round
CASTINGS.
WITHOUT
" in. of it quite square.
ruler does
A
103
pieceof
old
an
well indeed ; true up both flat
carefullydrill a hole through the exact
very
faces,and
centre
largeenough
to fit
needle, 2" in. of which
on
tightly
will make
a
a
thick
very
knittinggood steel
shaft.
From
the
sheet copper
wooden
four
small
body,
wood
and
a
and
Armature
centre
Cut
Fig.93.
with a file,
and saw
about
\ in
disc of the
fasten it
screws,
Fig. 94."
shown
cut
on
the
wood
counter-sink
Shaft
size
same
them
as
with
as
complete.
the copper rightthrough the
down
through the wood for
in
; the thickness
of
a
small
saw-cut
will be
quite wide enough for the slits.
Having gone so far,take off the two piecesof copper,
that they can
be put on again in the
mark
them
so
and cut a notch in the middle of each
same
positions,
with the
chance of contact
as in Fig.93, to prevent any
them on again,and glue into each side of
shaft ; screw
that
the slot two
little piecesof boxwood
or bone,so
file up
Then
they stand just above the copper.
the whole face,bone strips,
to a true
and screw-heads
and
even
Make
about
smooth
the
face,square with the shaft-hole.
yoke
for the armature
in. thick.
Cut
J in. wide, and bend
it as
^
from
sheet brasa
pieceabout If in. long and
shown to the rightin Fig.94,so
a
DYNAMOS
104
ELECTRIC
AND
MOTORS.
that it will touch the ends of the armature
the coils. It may
perhaps be necessary
little
longer than
If in. ; all depends
wire has been wound
In the centre
on
and
to
on
enclose
cut
it
a
how
much
to
fit the
the armature.
of this
yoke drill a hole
of
which
forms the shaft ; then
knitting-needle
carefully
adjust the yoke on the armature so that the
hole for the shaft comes
exactlyin the centre of the
and coils ; fasten both togetherwith twine to
armature
and solder the two
prevent any chance of shifting,
ends of the yoke to the two ends of the armature.
Now
place the steel shaft through the hole in the
yoke, see that it is perfectlyperpendicularto the
bit
Fig. 95." End
View
of
Brass
Bearing for Armature
Shaft.
face of the armature, and solder it in,taking care not
the armature
coils. As
to drop any hot solder upon
there will not
be much
chance of
truingup afterwards,
in the shaft.
try to get everything
square when fixing
The shaft bearingsare four piecesof brass cut from
the same
pieceas the yoke,or from sheet brass a little
about 1" in. by T\ in.,and two
thicker ; two measure
about " in. by -^ in. They are each drilled,
shown
as
in Figs.94 and 95, to take four small wood
and
screws
the shaft. The best way to drill the shaft-hole,
shown
in the centre of Fig.95, is to fix both pairsof brasses
to any spare
piece of wood side by side,just in the
gether,
positionthey will occupy on the frame,only close todrill rightthrough both at once,
and carefully
Before taking them
and true.
off mark
them
square
gettingthem back in their placeswhen
all,to ensure
they are to be fixed.
be made
of any kind of
The [standand blocks can
Their form does not matter much,
hard wood preferred.
at the top of the fieldmagnet is made
so long as the one
in Figs.88, 89, and 90.
as shown
The block for the bearings
and shaft can be a simple
MOTORS
ELECTRIC
CASTINGS.
WITHOUT
105
cube ; only both blocks must be of such a heightas to
bringthe centre line of the shaft on a level with the centre
The blocks
line of the field magnet ends.
have been
the stand after their positions
on
or
fastened
or
they may
screws
will
which
is
be
glued
determined,
through the bottom of the stand,
by screws
Four littlebindingbe fixed in both ways.
be wanted for the stand,as in Fig.87 (p.98),
sketch of the model in its simplestform
a
can
complete,but not drawn to scale.
the commutator, with its copper face
When
fixing,
outwards,can be slippedon the shaft rightup to the
with the length of the
yoke, the slits being parallel
A little strong glue dropped on each side,
armature.
back of the comthe yoke and the wooden
between
mutator,
will hold them
togetherquite tightenough,
if the shaft-hole is not large.
especially
Now
to each side
one
bringout the ends of the coil,
of the yoke ; cut them just long enough to reach the
face of the commutator, but not to
press againstthe yoke ; bare the ends,and solder one to
each segment of the rim,takingcare that no solder runs
edge of the
on
on
copper
up the copper face.
small disc
Cut
a
of
lead
stout
the end of the shaft in such
a
A, solder this
placethat it balances
the armature, commutator, etc.,and put it on true to
prevent any wobbling. This little disc has two uses :
the model
it makes
power,
it
and
easier
run
helps the
by
armature
of its balancing
means
over
the two
dead
points.
The
magnet
may
be screwed
now
silk ribbon
to
tighton
wound
havingbeen previously
The
prevent the wood cuttingthem.
then be put on the
farthest from
the one
can
side of the
block,so
againstit.
This washer
brass
bearings
other block in their proper places,
the magnets being flush with the
that
a
littlebrass washer
must
be soldered
on
can
work
the shaft
Fig. 94, where A is a lead disc,c o
the bearings,
the brush, E the commutator, v the
D
yoke,and a the armature.
as
shown
at
B
in
round
its seat,
the coils
DYNAMOS
io6
Put
it
so
the
on
Slack
the
that
AND
shaft,and
button
the
ELECTRIC
of
fasten
the
field
will
armature
MOTORS.
run
the
bearings.
magnet, and adjust
as
freely,as near
up
to the end of the magnet without any chance of
possible
one
on each side of the
touching.Fasten on the brushes,
shaft,and between the bearings; mind
they touch
Set the armature
nothing but the wood.
oppositethe
ends of the magnet, and bend the brushes so that they
each press gentlyon the commutator.
The dotted lines
Fig. 96." End
Figs.96
and
Fig. 97." Side Elevation.
Elevation.
97." Miniature
Electric Motor
with
Iron
Yoke.
in
for
Figs.93 and 94 (pp.102 and 103),show a position
the brushes,but their best place will be found after
the model has been set going.
Now
bringthe ends of the wires from the brushes to
and the two ends of the
the two first binding-screws,
field magnet coil to the other two.
four
from
binding-screws
nected to the two
Nos.
3
and
4
to
1 to
fore ends
the
two
Let
4, Nos.
us
1 and
number
2
the
being con*
of the field magnets, and
brushes.
By connecting
pole of a battery to Nos. 1 and 3, and the
other pole to Nos. 2 and 4, the armature
and fields
will be in parallel.In other words, if it were
a
dynamo, with a lamp where the battery is in the
it would
be said to be a shunt machine.
circuit,
If now,
with a short length of spare wire, Nos. 2
and 3 be joined,and one
nected
pole of the battery conone
to No.
1, and
the other to No.
and fieldswill be in series. Also
4, the
armature
by connectingNos.
1
MOTORS
ELECTRIC
and
4
with
a
spare
CASTINGS.
WITHOUT
piece of wire,and
the
107
batteryto
but the current,
Nos. 2 and 3, they will stillbe in series,
if you have not
not the motor, will be reversed" that is,
turned the batteryround,or placed the polethat was in
the other side. Another
No. 1 into No. 2, and the same
is to connect one cell to Nos. 1 and 2, and another
way
in either
the current
cell to Nos. 3 and 4, then reverse
Nos. 1 and
2,
Nos. 3 and
or
4, and
the
motor
will be
reversed.
littlecare
a
follows the
who
Anyone
may
have
a
foregoinginstructions with
small model
electric motor
at
a
U
Fig. 98." Side
Fijjs.98 and
99."
Elevation.
Fig. 99."
End
Small
Motor, with Horse-shoe
and Wooden
Saddle.
Elevation.
Magnet
merely nominal cost,the only expense being the copper
and some
small wood
wire,four small binding-screws,
wood
be
screws
can
; almost any kind of close-grained
used for the stand. All the rest of the stuff,
such as the
iron,odd bits of copper, brass,
etc.,might be got from
old scrap-heap.
an
Two other small motors
shown in Figs.96 to 106.
are
of this type, with a fly-wheel
A fair-sized motor
about
lj in. in diameter,will be found very handy to revolve
small Geissler tubes,or to work small models.
In the
here described,
the balance-wheel of a small round
motor
American
clock was
used for a fly-wheel,
which is about
The drawings are all in proportion,
f in. in diameter.
that a scale can
be made, which will serve
to work
so
from.
DYNAMOS
io8
Figs.96
ELECTRIC
AND
and
(p.106),show
97
MOTORS.
end
an
tion
and side eleva-
of the motor, with a small angle iron for a
which the magnet cores
either screwed
are
method, of
This
best ; but
course, is the
bolted.
or
neatest,and will look the
it necessitates the
as
yoke,into
of
few extra
tools,
about it,the drawings
simpler form, shown
use
a
will be mentioned
nothingmore
The
speaking for themselves.
complete by Figs. 98, 99, and 100, will be followed ;
for a magnet, held
here a piececf round bent iron serves
in its place by a small wooden
saddle and a button.
In fact,the whole motor
given in these three figures
be made from a few scraps of iron,
can
brass,and wood.
of Small
Plan
Fig. 100."
Fig. 101." Bearing
Brackets.
Motor.
will make
diameter,
the magnet, bent to the form and proportions
given in
Fig. 103 (p.110). Two littlebrown-paperbobbins,with
as in Fig.102 ;
ends,will be required,
very thin wooden
A
pieceof
soft iron
fill these with
No.
covered copper
of the bobbins
wire.
are
connected
To
matters
26
s.w.o.
in. in
or
It does not
the wire
ends
come
No.
28
matter
out
as
S.W.G.
silk-
at which
end
long as they
with the other.
one
connect
not
wire,\
coils of the
the
which"
binding-screws,and
magnet,
one
end"
it
will have to go direct to one of the
be clamped under
it,while the
other end has to be clamped under the foot of the back
bearingbracket. The wire from the other binding-screw
spring(seeFigs.98 to 100).
little stand of polishedor varnished
goes to the foot of the break
Having
made
a
MOTORS
ELECTRIC
wood,
fix
small block
a
CASTINGS.
WITHOUT
at
end
one
and
clamp
109
in the
and a
of a wood
screw
by means
wooden
button.
Figs.98 and 100 show this part of the
fitting.The bearingbrackets (Fig.101) are cut out of
and
magnet
bobbins
sheet brass.
magnet, has
The
a
back
one,
between
small hole drilled half
the bobbins
of the
throughit;the
other
hole drilled at its end ; the
form pointbearings
for the fly-wheel
spindle. These
carries
two
small
a
with
screw
a
brackets should be fastened to the
armature
revolve
may
of the electro-magnet
Fig. 102."
Two
100).
to
on
bracket
without
Bobbin
for
(seeFigs.98
the bobbins
the other end
and
close
cross
to the poles
possible
touching it (seeFigs.98
as
Magnet
Coila.
small binding-screws
are
side of the stand
coil
as
that the
stand,so
to
100);
is fixed under
one
fixed to the
one
end
of the
binding-screw,
of the coil is fixed under
the back
bearing.
delicate part of this model is the contact
is so small the pressure of
and as the machine
spring,
this springmust be very slight
indeed,
althoughmaking
The
most
good contact when required. One of the best methods
of making this springis to take a lengthof No. 24 s.w.G.
or
No. 22
i in.
at
one
cut the tipsquare, coil up the rest
foil,
of the wire to form a spiral,
and slipit looselyover
a
small wooden
peg in the stand (seeFigs. 98 to 100),
of
fixingthe bottom of the springto the stand by means
small spot of glue. The littleflattened tip must
be
a
bent with a pair of pliers,
that it will justtouch the
so
tipsof the teeth on the contact breaker,leavingthem
the arms
free whenever
of the armature
are
exactly
oppositethe polesof the magnet. The other end of this
contact springgoes under the other binding-screw.All
as
thin
silk-covered copper wire and bare about
end ; beat this out with a hammer, almost
S.W.G.
as
copper
MOTORS
ELECTRIC
The
model
binding-screw,
the
making
At
armature.
poles, the
the
tooth
proceed
by
fastened
to
so
going
round
coils
which
the
breaker
given
impetus
opposite
armature
the
to
its
to
it is
fly-wheel
the
a
immediately
the
spring touches
till the
is
core
allows
and
magnetic,
and
spring leaving
the
the
one
attracts
armature
;
at
wire
of
then
by
is broken
in
entering
current
the
moment
contact
the
the
magnet,
a
current
be
to
ceases
by
the
the
on
works
core
CASTINGS,
WITHOUT
tooth,
next
and
on.
small
A
dry
connected
to
ofl the
cut
wire
the
One
binding-screw,
one
be 1disconnected
must
convenient
most
pole
of
and
the
switch
stop the
and
current
small
A
binding-screw.
other
be
little model.
the
driving
will
cell
the
from
cell must
other
the
added
to
otherwise,
;
of
one
be
pole to
be
can
motor
for
the
one
binding-
screws.
half
A
hours'
at
work
the
taken
be
varnish
models, etc.,
on
painted
it
on
and
showing
when
a
from
six
it, either
from
the
little
to
eight
odd
at
very
made
the
be
times
of
oil
paints.
wire
Keeping
of
a
sealingblack.
for
The
is
electrical
bought,
model,
little
novelty.
the
bright
wire
the
to
taking
coils need
all brass
silk-covered
green
appearance
red
insulating properties,
special
green.
small, is
much
so
its
appearance
Brunswick
or
used
unless
coils
pretty
very
is
for
with
painted
ordinary
; and
will
complete,
paint,
account
far above
are
silk
give
charge
is
black
varnish,
be
drive
neatly
Sealing-wax
not
will
one
model
should
it
which
cell also
run
one
wax
for
be
can
When
sake
bichromate
and
well,
motor
or
-pint
will
which
XI2
CHAPTER
HOW
TO
DETERMINE
THE
A
IN
dealingwith
IX.
DIRECTION
OF
ROTATION
O?
MOTOR.
of the
which electric
on
principles
motors
act,we will take as an example the Siemens H.
girdertype. This form of motor has been chosen partly
of construction,
because of its simplicity
partlyas it is
such a favourite form for small motors.
In this chapter
endeavour will be made to make the principles
clear
an
of the laws that govern
this type
some
by illustrating
of machine,without in any way going into the subject
some
of construction.
The
principallaw to understand is that governing
what happens when
wire is
a lengthof covered
copper
wound
round a bar of soft iron,
and an electric current
is passedthrough the wire. It is,of course, well known
that the iron becomes
longas the current
greatimportanceto
as
a
magnet, and
flows ; but there
be considered.
are
a
magnet
other laws of
iron,as N s in Fig.107 ; hold the
end N in your left hand, and wind a length of covered
the iron,beginning from your
wire upon
left
copper
hand and proceedingtowards the other end,describing
circles with your right hand in the same
direction as
that is,away
from you on
the hands of a clock turn
If you
top of the iron,and towards you underneath.
from
now
pass an electric current through the wire coil,
the left-hand end to the right-handend, as shown by
that is,if you
the carbon plate
connect
the arrows
of an active batteryto the left hand, and the zinc plate
the
to the right the left-hand end of the iron becomes
north pole of a magnet, and the end that is at your
righthand becomes the south pole.
Take
a
small bar of
remains
"
"
"
DIRECTION
take the iron
Now
way
"
with
ROTATION
OF
that
your
bar,but
is,as you wind
righthand in
by
of
on
a
wind
MOTOR.
A
113
it in the
reverse
the wire describe circles
direction contrary to that
in Fig.108
that is,
as
clock,
goingunder the iron,aud
pass the wire from you when
bringit towards you when coming over the top. Then
in at the left-hand end and
send the current,as before,
out at the right,
as shown
by the arrows, and the poles
taken
the hands
OF
a
"
sr/y / / "|H
\
Fig. 109.
Nl\\\\\k
jj
V
V
v
V
'
v
Fig. 110.
Figs. 107
Directions
of
Magnetism in Bar
to
110."
will be reversed"
that
is,the
Currents
and
Resultant
Magnets.
polewill be towards
the righthand, N, and the south poleto the left,
s.
direction as Fig.107,
Fig.109 is wound in the same
but the current flows,
as shown
by the arrows, from the
the polesto be
righthand to the left ; this will cause
reversed. Fig. 110 is wound
in the same
direction as
Fig.108 ; but by reversingthe direction of the current,
as shown
by the arrows, the polesagainbecome reversed,
This is what happens in
as occurred in the other case.
when the brushes cross the insulating
a shuttle armature
stripsof the commutator
: the direction of magnetism
in the armature
set up
is
current
by the armature
reversed by the current beingreversed.
A very good way to master this rule is to get a piece
of
"
wood, and
N."
Then
ft
mark
one
end
north
"S"
on
get a pieceof string;
and
one
the
other end
end tie a
label,
DYNAMOS
ii4
ELECTRIC
AND
MOTORS.
"
marked
the other end tie another
on
+," or positive,
label marked
,"or negative. With the stick and the
the foregoing
rule.
stringpractise
The next law to be understood is (a)if polesof the
kind are brought near
each other,
same
they will repel
another ; (6)if two different polesare brought toone
gether,
they will attract one another that is,north to
"
"
"
Tl'l'l
Fig. 111.
Figs.
Ill
and
north,repulsion
; south
south,attraction.
In the diagrams of
commutators
to
at
112.
to
motors
simplifythe drawings.
the
the
moment
two
Series Motors.
south,repulsion
; but
brushes
and
"
Fig. 112.
have
(Figs.Ill
been
left out
116),the
in order
be understood
It must
poles
to
north to
of
the
armature
that
are
polesof the field magnet, the two
the insulating
brushes are restingupon
stripsof the
commutator
; immediately after that,as the armature
rotates,the direction of the current is changed through
and its poles reversed. Though this is
the armature
in this case
fact in practice,
not the exact
we
may
oppositethe
it to be
assume
In
two
a
current
motor
passes
so.
the
type driven in series,
either first round the magnets, then
of the Siemens
DIRECTION
ROTATION
OF
OF
A
MOTOR.
115
through the armature, and back to the batter y, as in
first through the
Fig.Ill, or in the reverse
direction,
armature, then the magnets, and back to the battery,
It may
as in Fig.112.
curious,but whichever
appear
way a current is sent through a series motor, as shown,
it will rotate the
Let
us
from the
follow
is as shown
to be reached
observed,is wound
way.
the
battery. We
the current
core
same
winding
in
is the left-hand
as
Fig. Ill, starting
will suppose that the direction of
The firstmagnet
by the arrows.
the iron
it will be
this,
bar in Figs.108 and 110,
been understood,
it will
one
;
foregoinglaw has
be seen
that a south pole is left behind the winder.
Crossingover to the other core, the winding is done
shown
in Fig. 108, and this produces a north pole
as
After this the current
at N.
brush,then
goes to one
(theseare not shown),and into
throughthe commutator
and
if the
the armature, wound
in the
same
as
way
the
poleto
the bar in
Fig.109, which producesa north
rightand a
the current againgoes
south poleto the left. After this,
through the commutator, through the other brush,and
to the battery.
so returns
shown
in Fig.
The positionof the armature
as
is a little beyond the horizontal,
that the
Ill
so
brushes
are
in contact
with
the commutator,
and
the
Now
through the whole machine.
study what happens. The south pole of the armature
the south pole of the magnet, and
is againstor near
is near
the north pole
the north pole of the armature
This means
mutual
the
of the magnet.
so
repulsion,
indicated
takes the motion
armature
by the curved
above it,
arrow
which, by the way, shows the direction
of motion in all the diagrams. Influenced by repulsion,
this motion continues until the south poleof the armature
the north pole of the magnet ; then,as they
nears
of different poles,
are
they will attract each other until
has arrived exactly
the south pole of the armature
oppositethe north poleof the magnet. At that moment
the insulating
stripscross the brushes and change the
current
will flow
DYNAMOS
n6
ELECTRIC
AND
MOTORS.
polesof the armature, and what was formerlythe south
becomes
its north pole,and
now
pole in the armature
like poles are again togetherand mutual
repulsionis
of the same
set up, causinga repetition
series of motions
as has justbeen described.
If the batterycurrent is now
shown in
as
reversed,
and the winding is followed out, it will
Fig.112 (p.114),
be found that every polehas been changed,so that again
have like polesto like,
and the motion becomes the
we
Fig. 113.
Fig. 114.
and
Fig. 113
same
in
as
driven
in
whichever
from
a
the
magnets
Fig.111. This means
it will turn in
series,
the current
way
When
114." Shunt
motor
isdriven
batteryis
and
part
that if
the
a
motor
is
direction,
same
goes.
as
a
divided"
to
Motors.
machine,the
part being shunted
shunt
the armature.
current
to the
After the divided
has
passedthroughthe machine,it again unites
in one
wire and returns
to the battery.By following
the windingsand the direction of the current in Fig.113,
current
it will be
as
s
in
seen
that the left-hand limb
Fig.Ill (p. 114),and
the other must, of course,
be
that it is
a
north
s
is the
a
south
pole,as
same
pole;
the two
DIRECTION
OF
limbs
of the magnet
oppositepoles. Now
which
current
enter
on
passes
ROTATION
are
OF
always
follow
out
through the
the left-hand side and
MOTOR.
A
wound
that
so
as
branch
armature
be wound
117
to
give
of the
; this will
with
a
coil
going in the direction shown in Fig.109 (p.113); this
and a south pole to
will give a north pole to the left,
the right. The current
then goes through the commutator,
etc.,after which it joinsthe current round the
magnet, and so returns to the battery.
In this case it will be seen
that we have unlike poles
Fig. 116.
Fig. 115.
Figs.115 and
116." Motors
driven
with
Two
Batteries.
and the
each other ; these exert mutual
attraction,
to that shown
rotates in the direction opposite
armature
near
Figs.Ill and 112 (p.114).
Now
study what happens when the shunted part of
the current is reversed through the armature, and the
part of the current throughthe magnets is left as it was.
Fig.114 will show this. We have like polestogether,
and the motion of the armature
exertingmutual repulsion,
direction as shown
is reversed,
turningin the same
We should also get a reversal by
in Figs.Ill and 112.
reversingthe current round the magnet whilst keeping
in both
X.
CHAPTER
HOW
THE
TO
small
illustration
those
who
MAKE
A
SHUTTLE-AKMATURE
shown
electro-motor
(Fig.117) is
have
access
parts. It is a machine
suited
to
a
in the
to
lathe
the
for
accompanying
requirementsof
turning certain
that will look very
Fig. 117." Shuttle- Armature
if
MOTOR.
Motor
well indeed
Complete.
in the fittingand
good workmanship is shown
of the various parts. But some
careful fitting
finishing
is required to make
it run
well.
When
properly
made, it will drive a small polishingor dental lathe,or
fretwork
a small
machine, or a small drilling-machine,
of
with a batterypower
or even
a lightsewing-machine,
acid cells,
three or four quart chromic
the
some
or
equivalentelectrical energy from any other source.
The set of castings
requiredconsists of two malleable
iron field magnet cores and bridges,
at Fig.118,
as shown
each measuring 4" in. in length by 2J in. in width ; one
malleable
iron casting (Fig. 119) for the
armature,
DYNAMOS
120
ELECTRIC
AND
MOTORS.
measuring Z\ in. in lengthby If in. in diameter ; two
gun-metal castings,
1| in. in diameter (Fig.120),for ends
of the armature
brass castings of four-legged
; two
spidersfor the bearingsof the spindle; one brass casting
of a pulley,
l\ in. diameter by T9^ in. thick ; one brass
1 in. diameter
castingof a collar,
by " in. thick ; two
brass end-pieces,
2^ in. by f in. (Fig.121),to form feet
for the field magnets ; one
brass castingfor a brush
rocker,2" in. in length(Fig.122) ; two brass castings
Fig.
118."
Field
Magnet
Casting for Shuttle-Armature
Motor.
(Fig.123); two brass castingsof set
for the brass nuts, brass tube
screws
(Fig.124); castings
for commutator, and a stripof phosphor bronze for the
These having been obtained,
will set about
brushes.
we
the various parts and puttingthem
and finishing
fitting
together.
if rough, will require
field magnet castings,
The
them
fit and have a presentable
to be filed to make
All lumps should firstbe filed down with
appearance.
of brush-holders
a
flat bastard
next
not
file. The
be smoothed
to do
of the
cores
more
with
than
should
a
channel
half-round
smooth
be
care
file,
must
beingtaken
the
casting.The corners
rounded
off,to prevent them
of the wire aa
insulatingcover
cuttinginto the
The
this is being wound
o*n.
smoothed and the ends trued,to
from
for the armature
outsides
make
may
the whole
now
be
fitwell
MOTOR.
ARMATURE
SHUTTLE-
A
isi
the field magnet is usually
the under one.
The under field
together.The top castingfor
a
little thicker than
will have the
magnet casting
and
therefore have two
must
receive two
These
Fig.
119.
Casting
holding-
or
each
hoies drilled at each
small screws, which
Armature
"
brass feet
at Fig.121, fitted under
shown
pieces,
down
two
pass
end,
end.
through the
for Shuttle-Armature
Motor.
the lower
brass feet and
as
castinginto the top casting,
shown in Fig. 129 (p.126). Small holes for set screws,
also be drilled and
must
to hold the feet of the spiders,
of the armature
tapped in the corners
channel,as shown
Fig. 120." Gun-Metal
at
Fig. 129
; these
screws.
Thus
of
black
Japan
The
armature
are
Casting for Armature
fitted with
malleable soft iron.
and
at
smooth
with
brass
This must
be filedsmooth
ends,and the channel must be made
shown at
file. The gun-metalend-pieces
the
a
round-headed
prepared,the castingsmay have a coat
and be set aside to dry.
is of the Siemens H-girder
type, in one
castingof
true
Ends.
122
DYNAMOS
Fig.120
will be fitted to the ends
hold
AND
ELECTRIC
the steel spindles.These
are
MOTORS.
of the armature, to
made from two 2-in.
lengthsof "-in.steel rod,turned true and smooth down
in. diam.
Turn the end-pieces
to -j8,,smooth, drill a
T\ in. hole through the boss of each, and drive one end
of each spindleinto each boss.
will be secured to the ends of the
The end-pieces
"
Fig. 121."
Gun-Metal
Foot
for Motor.
armature, after being fitted true to it,by small brass
screws
; holes must
piecesand
the
screws.
therefore be drilled throughthe end-
into the armature, which is tapped to receive
In one of the end-pieces
drilltwo extra holes
for the ends
of the armature
coil to
come
through,and
bush these holes with small tubes of ivoryor bone.
Fig. 122." Rocker
the ends
are
and
it by
fitted on, mount
When
for Brush-Holders.
the armature
in
a
lathe,
turningaway justenough to take off the
and screwrough skin. This done,mark all the screws
holes to correspond,
be identified when
so that they can
is being put together.Take off the ends,
the machine
and dress the web and channel with shellac or good
sealing-waxvarnish,then set aside to dry,ready for
winding.
Brass castingsas
shown
at Fig. 117 fulfil the
double purpose
of clamps to hold the field magnets
true
A
MOTOR.
ARMATURE
SHUTTLE-
123
spindles.
with
be drilled to fit the spindles,
These must
now
holes in each foot to receive the holding studs,and
with small oil holes for each bearing; then they must be
boss
filed smooth and neatlypolished. The projecting
be turned to form a
of these bearings must
of one
bearingfor the brush rocker (Fig.122),which will fiton
togetherand
of
bearingsfor
Tig. 123." Casting
like
sleeve.
a
The
The
castingfor
armature
Brush-Holder.
insides of the
should also be turned
The
for
the
spiderlegsand
bodies
smooth.
the brush
hole in the centre
must
rocker is shown
at
Fig.122.
be bored to fitthe boss
on
be
bearing above-mentioned ; and a hole must
drilled and tapped in the edge of the rocker to receive a
for fixingthe rocker in any requiredposition.
set screw
the
Fig. 124." Casting for Milled
Two
as shown
rough brass castings,
Head
Screw.
Fig.123, must be
turned and filedto the form shown at Fig.125 (p.124),
to
and these are held in holes,
form brush-holders,
B B, drilled
through the ends of the rocker (Fig122). The holes in
drilled T\ in. in diameter,
the ends of the rocker are
with vulcanite or asbestos board,with a
and bushed
collar of the same
each side,
to insulate the brushon
holder from the rocker.
A fairlygood bush can
be
cut from a pieceof rubber tube,with two collars of thin
cloth to
and
011
come
between
the rocker
on
the other ; but
one
the shoulder
side,and
indiarubber
at
of the brush -holder
the nut
and
is liable to be
the rocker
destroyed
DYNAMOS
124
ELECTRIC
AND
MOTORS.
by oil. In Fig.125 the part B is first turned to " in.
diameter,and a thread chased on it to receive a brass
The plain part to the left of the chased thread
nut.
be drilled transversely
must
with a -j^-in.
hole, c, to
receive the conductingwire,and this hole is met with
another,E, drilled from the end,and tapped to receive a
with a milled head,as shown
at Fig. 126.
binding-screw
Fig. 125." Brush -Holder
complete.
Fig. 126."
Screw
Head.
Milled
other end of the brush- holder,
D, is turned
The
slot gV in. wide is cut up
the holder is filed flat,
and
to the shoulder
a
both
the hole in
a
A,
with
one
parallel,
side of
^ in.hole is drilled through
jaw is tapped to receive a
brass screw, which passes freely
throughthe other jaw.
brushes
The
are
stripsof phosphor bronze foil,
2 in. by ^ in.,
Six
at Fig. 127.
cut to the form shown
jaws ;
one
Fig. 127." Brush.
stripssoldered togetherat one end form a pad.
A slot,
\ in. by i in.,is cut through the middle to
There is a
receive the adjustingand tightening
screw.
brush-holder (Fig.125)at each end of the rocker,
and in
the jaws of this the brush is held.
A two-part commutator, made of a brass ferrule split
into two equal parts,will be required. On this form of
the two ends of which
there is only one coil,
armature
of these
are
connected
to the two
brass tube which
partsof the
commutator.
will be suitable for the
has
castings
internal diameter
This is fitted on
boss
with
\
of \\ in.
in. in width, bored
a
The
a
hole which
an
boxwood
exactly
A
fits the
the
SHUTTLE-
that
spindle at
bushed
holes
MOTOR.
ARMATURE
end
in it.
the
of
armature
ferrule is
The
125
now
with
to
be
equal parts, and on each side of the
to have the
so
as
lines,
dividinglines scribe two more
three lines on each side i in. apart. Through the centre
scribed into two
of each
boxwood
of the two
side lines drill small
to receive brass screws,
Countersink
the mouths
as
shown
holes into the
in
Fig.128.
eight holes,and
of these
tight;then cut the ferrule into
shown
two
oblique cut, as
equal parts with an
with
This is best done
at
a
hack-saw,
Fig. 128.
to make
a clean cut
so
as
through the brass and into
with its split
the boxwood_beneathit. The boss,
ferrule,
in the
screw
screws
Commutator.
Fig. 128.
"
pressedon the spindlewith the inner ends of the
obliquecuts adjustedso as to coincide with the wire
is now
holes in the armature
Winding
ends.
the armature
off 60 ft.of No. 20
wire,roll it into a
S.W.G.
is
a
simplematter.
double
and
cotton-covered
soak
it for
Measure
copper
a quarter of
hank,
hour in melted paraffin
an
wax, then hang it up to drain
in the left
and cool. When
cool,take the armature
hand, and the wire in the right. Place the commencing
at the loft side
end of the coil with 2 in. left projecting
with the left thumb
of the channel,and hold it down
whilst the wire is wound
closelyaround the web of the
in close regularturns,side by side,
to the right
armature
then back againwith the same
side of the channel,
care
until all the wire has been wound
in
and regularity,
on
gether
regularand even
layers. Then twist the two ends toto keep the coil from
unwinding. Test each
layer for insulation as it is wound
on, and test the
whole coil againwhen complete.
SHUTTLE-ARMATURE
A
S.W.G.
double cotton- covered
layer
for
has been
core
6
in.
than
more
this in under
the
is needed
to
of wire
the turn
last
make
so
as
test each
turn
off the wire
reached,cut
127
wire,and
copper
When
insulation.
MOTOR.
so
leave
to
as
the
each
on
turn ; pass
to form
kind
a
it tight to prevent the wire
and draw
half-hitch,
from unwinding ; then give the whole a dressingof
each coil in its place,
sealing-waxvarnish to secure
and to givethe whole a finished appearance.
When
the machine
is being put together,
the coils
be connected
here
must
as
described,and shown
The finishing
end of the first coil at A
at Fig. 129.
be bared of the cotton
must
covering and cleaned ;
also must
the commencing end of the second coil
so
the next core
at B.
on
Dip both cleaned ends into
tin them with a hot soldering-bit,
some
solderingfluid,
twist the tinned ends togetherwith a pairof pliers,
then
to fuse the
givethem a final touch with the soldering-bit
of
solder and unite them.
and
Each
end
must
connected,namely,A to B, c to
be passed down
ends c D may
two
be thus treated
D, and E to
holes made
The
F.
in the
of the motor, and connected
beneath.
The two
free ends above the upper polewill then go, one to one of
and the other to one of the terminal bindingthe brushes,
base
screws
on
the
base,if
the coils
series with the armature
the brushes
with
;
or
if the coils are
the coil
on
be
connected
in
both will be connected
to
are
to be
the armature,
so
to
connected
as
to
make
in
parallel
a
shunt
motor.
the parts together,
the field magnets
fitting
be fitted first,
the ends of the coils soldered and
may
the screws
tucked in out of sight,
holdingthe two cores
inserted and screwed tight,
and the brass feet screwed
on.
Next, fit the alreadyturned and polishedspidermutator
bearingto the end oppositeto that on which the comis fixed. Then
put in the armature, slipthe
this bearing in
and screw
other bearingon its spindle,
round
the armature
turn
its place. Now
by hand,
in
the
and see that it runs
truly
tunnel,not touching
When
DYNAMOS
128
ELECTRIC
AND
MOTORS.
anywhere, but equidistantfrom the sides at all parts.
The back pulley (see Fig. 117, p. 119) should now
be
the spindle,and tightened on
fitted on
it by means
of a small set screw
passingthrough the boss on the
outside.
The
the
to
One
screw.
on
next
may
outside
of
of the brushes
the top of the
press
are
rocker
the
be
fitted on, and
bearing by a small
will have itsfree end
under-side
set
bearing
commutator, and the other brush
lightly
againstthe
cured
se-
will
of the commutator.
The brushes B, brush-holders H, and rocker R. complete,
shown in Fig.130.
The exact position
of the brushes
Fig.
130.
"
Brush-Holders, Rocker,
will be determined
the commutator
correct
by the direction
runningaway
Brushes
complete.
of rotation of the
from
ture,
arma-
the brushes.
be found
set these must
angle to
and
The
by experiment.
easilybe moved until the best effect has
been obtained,then fixed in this positionby the set
The collar is now
screw.
slippedon the spindle,the
armature
brought forward until it runs free in its proper
and the collar tightenedto prevent undue end
position,
shake of the spindlein its bearings. A little end play
but side shake, due to
shake is always admissible,
or
be allowed.
loose fittingin the bearings,must
never
The
rocker
The
motor
of
can
now
may
oak, teak, or
terminals to the
be
mounted
mahogany,
wire coils,
as
of the wires
The
insulation
may
be tested in the
manner
and
a
base
made
furnished
with
brass
shown
on
the
on
at
Fig. 117 (p.119).
field and
armature
described in Chapter VII.
I29
XI
CHAPTER
UKTY-WATT
DYNAMO
UNDEETYPE
AND
MOTOR.
followingfiguresshow a dynamo which
lightthree 10-volt 5-candle-power
lamps,or
when suppliedwith current from
as a motor
The
The
illustrations
are
all to
a
will cither
work
a
well
battery.
scale of one-half full
them.
be measured
from
size,and dimensions may
Assuming that the castingsand other materials are
leady,it will be convenient to consider the work of
construction in three divisions first,
mechanical
struction
conthe
; second,insulation ; third,winding on
wire and connecting
up.
Commence
with fitting
up the brackets and armature
;
be drilled on the bearings
the holes for the shaft must
A, A, Figs.131 and 132 (pp.132 and 133);at each end of
the boss,
punch a centre in the middle of the round part of
the top of the bearing. The hole should be drilled rather
less than "in. diameter,a little way in from one
end
then reverse
the bearing,
and drill up a littlefrom
first,
the other end,reverse
again,and so on until the holes
The oil cups B, B, Fig.132,
meet
at about the middle.
be ditlled as shown, the hole at the bottom,about
can
being drilled through into the bearing^a in. diameter,
hole to allow oil to pass. Drilled thus,the holes for
the bearing will be found to be somewhat
rough and
perhaps not exactlyin line ; this will be remedied by
rose-bit passed carefully
a
or
reamer
through. Use
littleoil as lubricant,
and work from one
end only.
a
If the drilling
has been carefully
done with a drillabout
"
s1^in. less than the finished size the hole will be reamed
Care
quite smooth.
bearingsurfaces when
operations.
I
must
be taken
handling the
spoilthe
castingsfor other
not
to
DYNAMOS
130
The
bore
ELECTRIC
AND
of
the
MOTORS.
field-magnetcasting,Figs. 133
and 136, if well cast will be very nearlya true circle ; it
should be cleaned out with a file to remove
any lumps
To take
irregularities.
through with a boring
bar on the lathe makes the best job,but good results may
be obtained without this if a good castingis secured.
To get the bearingsin alignment a dummy
armature
be made.
and shaft must
Get a pieceof iron or
now
steel rod just the length of the armature
shaft and of
and on this mount
a convenient
diameter,such as f in.,
tightlya pieceof hard wood, about If in. diameter,of
the lengththe armature
will be,and in the same
core
in the bore of
position.Turn the wood to fit tightly
and turn the rod also at each end to fit
field-magnet,
the bearings. Place the dummy
tight in the bore,
and
fit the
slipthe bearingcastingson the spindle,
end lugs D, Fig. 132, to bed flat on
the sides of the
be
field-magnet
out, the castings
may
; if they are much
hammered
until they are somewhere
and the
near
right,
final adjustment effected with the file. A little red
or
mixed
ochre
with
oil and
a
cut
the magnet will
It is importantthat these
smeared
on
lugs touch.
bed properly,
brackets should
or
they will not be in
line when screwed in place,
and the shaft will run stiffly.
The holes for the screws
E, Figs.132 and 133, may be
drilled in the bearingcastings
the bearingson
; then slip
the dummy shaft and mark the field-magnet
by drawing
the point of a scriber round the holes in the castings.
Some
chalk rubbed on the magnet where the bearings
will assist to show the line. Tapping holes for
come
be drilled about | in. deep in the
^-in. screws
may
show
where
centres
the
of the marked
circles. Mark
off holes in the
tions
holding-downscrews, the posithe drawing(see
F, Fig.131). The
field magnet feet for the
beingtaken
from
be about ^ in., chamfered
of the holes may
intended to be used.
to suit the wood screws
diameter
The
armature, Figs.134 and 135, is now
its shaft is of steel 7f in. long ; if made
quitestraightand true,the diameter
to be made
;
from rod that is
can
be /" in.,
so
DYNAMO
UNDERTYPE
central
is better
to have
131
turned; but it
and take a lighl
f in.,
portionneed
that the
MOTOR.
AND
be
not
the diameter
At th"
along, reducing to "" in. diameter.
pulleyend a length of \\ in. has to be turned down to
end a lengthof
and at the commutator
form the bearing,
that
so
1\ in. These necks should be left a littlelarge,
they can be fitted in after the core discs H, Fig. 135
the screwingup of the
are
tightenedup in place,
(p.138),
clamping nuts J having a tendency to bend the shaft.
The screwed portionsfor the clamping nuts are cut as
with about
shown, for about \ in. at each end ; a screw
all
cut
twenty threads to the inch is necessary, and is best
on
lathe
screw-cutting
a
; but if this is not
thread may be started with
with a comb chaser.
About
120
stock and
discs,about ^
core
cut
the
available,
dies and
finished
in. thick,
must
now
be
prepared. The central holes must pass over the shaft
for if not flat the
be filed off,
easily
; any burrs must
uneven
parts to
screwing-upof the nuts will cause
bend
the shaft.
K,
groove
To
make
In the middle
Fig. 134, \ in. long,to
a few discs should
this,
and put on the shaft when
It is a difficultjob to turn
if left till the
discs
with
a
core
the shaft
on
of the
is the circular
core
take the
be reduced
side of each
thin coat of enamel
in diameter
half the other discs
out this groove
is complete. Before
one
binding cord.
or
on
are
on.
the lathe
threadingthe
should be painted
Brunswick
black and left
The
clamping nuts J, Fig. 134 (p. 138),are
circular piecesof brass f in. diameter,with a hole in
the centre drilled and tapped T5^in. to fit the screwed
to
dry.
shaft.
The
side of the nut
which
be faced up true
rounded off
the outside corner
discs should
Two
p.
flats
parallel
138)to
take
Put the
a
filed
are
on
on
as
a
is to go next to the
screw
mandrel,and
shown
the
in the
drawing.
edge (seeFig. 135,
spanner.
discs
the
the paintedsides all
shaft,
that the core
is in the right
see
facing one way;
and that the channel
positionlengthwayson the shaft,
L, Fig. 135, for the insulated wire is straight;then
core
on
132
screw
DYNAMOS
up the nuts
AND
as
ELECTRIC
MOTORS.
leavingthe
tightas possible,
flats
flush with the channel ; a littleoil between the face of
the nut and end disc assists. Test the shaft between
centres,and, if required,straightenit ; then
down
the necks to fitthe
bearings.When
a
good
turn
fit is
attained,
placethe armature in the field magnet and fix
the brackets in place. The armature
should be central
in the bore and should spin freelywith the fingers
; if
the shaft bearings
until it runs
ease
stiff,
freelyand yet
UXDERTYPE
without
shake.
The
with
An
DYNAMO
AND
end movement
armature
core
should
MOTOR.
of about
coincide
133
visable.
-^ in. is ad-
lengthways
the field magnet ; should it projectfrom
one
side
other,the magnet will try to pull it into
ing,
a beara central position.In doing this it pullsagainst
which will have a tendency to get hot. Any of the
core
platesthat projectcan be levelled down with a file.
consists of a pieceof brass tube M,
The commutator
more
than
the
DYNAMO
UNDERTYPE
135
lessens the
gradually,and
sparking and wear.
important; a deviation of
of slant is not
amount
MOTOR.
AND
iV in. each side of the
centre
line will do.
The
about
down
Saw
to
into it,so as to separate the segslightly
ments
clear of
completely; see that the slot is perfectly
to keep the segments apart and prevent
cuttings
; and
insert a thin stripof
dust from gettinginto the slot,
the bush
wood
and
mica.
or
little cement
A
shellac varnish
or
will
each brass segment, at the end next
nick just largeenough to
a
core, saw
keep it in place. In
to the armature
of the armature
allow the ends
wire to go in and fit
be gently
now
complete commutator
may
tightly.The
driven
the
on
the
shaft,
slots beingin line with the round
at
by Fig.137 (p.142)"that is,
rightanglesto the centre of channel L, Fig.135 (p.138).
The oil-guardK, Fig. 133, can
be of brass,and is
driven tighton the shaft after the commutator
is in
for the pulleyends can be tapped
place. The oil-guards
made to fit the
to fit the screwed part of the shaft,
or
plainpart,and can be put in placeafter the armature
part of the
core,
shown
as
is wound.
To fitup the brush gear, Figs.131, 132, and 133, commence
with the rocker T, Fig. 132 (p.132). This allows
the brushes to be moved
to find the
Bore
on
a
round
the commutator
which givesbest
position
results when
hole about " in. in diameter
to the boss
on
the
so
bracket,
in order
working.
in the boss
that the
u
to fit
is straight
arm
and square with the hole. Put the rocker on a mandrel
and face each side of the boss. Now
put the bearing
bracket
on
a
mandrel,and
down
turn
boss to fit the hole in the rocker.
the side of the rocker is to take
in
Fig.
piece of
132 ; this
wood
should
projecting
small boss at
set-screw,as shown
fit in the
thread.
A
to
requiredfor the crosspiece
carry the brush-pins(seev, Fig. 131). This should be
filed up about \\ in. by " in. by \ in. thick ; the angle
be filed out square to the hole in boss,
to receive it must
that when
the crosspiece
is fixed in,the pins will
so
come
hard
screw
a
The
the
to
parallel
is
the shaft. Mark
the exact
centre
of
DYNAMOS
136
the
screw
and
crosspiece,
\ in. diameter.
in the
equallyat
ELECTRIC
AND
MOTORS
drill a hole to clear
a
countersunk
Now
angle of the
each side,
and
in position
placethe crosspiece
rocker arm, so that it projects
with
Fig. 133." End
a
View
scriber mark
of
off
on
the
Dynamo.
of the hole ; drill and tap it to fitthe
position
be fixed in place. At
now
The crosspiece
can
screw.
| in. on each side of the middle,mark centres for the
and drill
the centre line of the crosspiece,
on
brush-pins,
brass the
and tap two holes " in diameter.
be
brush-holders w, Fig. 131 (p. 132),must
The
should be filed all over, and
The castings
finished next.
the ends
squared.
Mark
the centre
at
one
end
of the
DYNAMO
UNDERTYPR
circular
it. The
MOTOR.
AND
137
hole through
and drilla -"-in.
part of the casting,
slots for the brushes
be cut from
can
one
end
Fig.131. They should be
with the holes
^ in. long fully-^ in. wide,and parallel
diameter
alreadydrilled. Drill and tap the bosses for "-in.
These
bosses may
be
clamping screws, as shown.
in the screw-holes
turned by puttinga small mandrel
in a
before they are tapped and holding the mandrel
chuck.
To make
the pins,if straight
^~in. brass rods
chosen to fit the holes in the brush-holders they will
are
onlyneed to be polished. Screw one end of each pin for
a length of ^
in.,and at the other end drill a small
hole through the diameter.
In this hole placea pin tc,
prevent the brush-holder from being forced off by the
be screwed tightly
in place
spring. The pinscan now
Make
in the cross-arm.
two hexagonal nuts to screw
the threaded part which projects
on
through the crossto clamp the flexible wires x, Fig.132,
arm
; these are
which carry current to the terminals.
For adjusting
the tension on the springs,
two
as
collars,
shown, are
required.They may be made from |-in.brass rods,
drilled to fit the pins,and each should be fitted with
to fix it in the requiredposition.A small
a set-screw
with
a
saw,
as
dotted in
shown
hole is drilled in the face at
take
one
end
of the
be drilled at the end
spring,and
side of each
a
collar to
similar hole should
in each brush-holder
to take
the
spring. The spiralspringsare made
of hard brass wire,about No. 24 S.W.G. ; one
is coiled
and the other right-handed.
left-handed,
The terminal blocks Y, Fig. 133, are filed all over
and polished,
and holes are drilled and countersunk
to
other
end
one
take wood
of the
screws, which
terminal- board.
block
at the
cheese-head
brush-wires
end
A
hold
the blocks
hole is drilled and
next
screws,
the commutator
which
clamp
down
on
the
tapped in
each
to
take
J-in.
the field-wires and
(seeFig. 131). Holes are drilled through
the upright blocks to receive the outer-circuit wires
which are held by set-screws put in from the top.
The
terminal-board
be
z, Figs. 132 and 133, can
DYNAMOS
138
made
from
ELECTRIC
AND
MOTORS.
piece of mahogany about \\ in. by
2 in. by f in. thick,
and polishedor varnished according
to taste.
Holes are
drilled in it to take two ^e-in.
a
countersunk
The
magnet.
which
screws,
fix the
board
to
field
the
holes in the magnet should be drilled and
Fig.134."
marked
tapped last,and
(SideView).
Armature
off for
positionfrom
the
terminal-board.
The
drivingpulley(shown in Figs.132
suitable for either a flat or a
of
manner
to suit the
dimensions
be made
dynamo is to be driven from a
1 in. diameter
a pulleyabout
Fig. 135."
V
size,with
a
diameter.
The
Armature
groove
width
to
driving.
foot lathe
hand
or
all is
over
a
If the
wheel,
convenient
(End View).
take
of the
and 133) may
round belt,and of
round
belt of
^
in.
pulley should be about
a
taperinghole to fit a
and it can be bored with
f in.,
and
taper shaft,or hole and shaft can be made parallel,
put in the boss will hold them together.The
a set-screw
fitshould be
between
good ;
centres
and when
and
the armature
has been put
the pulleyfinally
turned true in
the mechanical construction is finished.
its place,
To proceedwith the insulation. Take the armature
out
and
the
bearingsoff.
Examine
the field magnet
UNDER
DYNAMO
TYPE
MOTOR.
AND
139
wound, and with a file smooth
and all sharpedgesand
off all corners, any rough places,
pointslikleyto cut through the insulation. Wrap two
layersof thick brown paper round each core, sticking
the wire is to be
where
them
with shellac varnish.
on
cheeks
cardboard
fitthe
core,
the cheeks
so
the
on
sprung
will extend
slantingcut is
paper is pasted over
if
cores
a
a
the insulation and
that the wire
at any
paper
cannot
made
point.Then brush a thick
wrapping and cheeks, and
across
the cut to
one
keep
pushed to their
Carefullylook over
sound everywhere,so
into contact
come
be
they can
been
that it is
see
133, to
f in. from the
to suit ;
be made
must
pieceof
the cheeks have
it together
when
placesat the ends of the core.
side and
about
rectangular
and
flangesQ, Figs.132
or
; the wire
cores
Cut out four
with
the iron
of shellac over
coat
leave them
until
the
quite
dry.
The
Smooth
all
be
must
armature
in
treated
projecting
points,edges,and
the wire is to be wound
the channel where
singlelayerof thick brown
paper
cover
similar way.
a
along
corners
; then with
the
a
channel,the
at the
of the core, and the shaft to the oil-guard
at the other end.
pulley end and to the commutator
ends
Leave
the
to
so
channel,
the edges ;
wound
have
a
projecting
the paper
on.
an
as
it can
The
extra
to be
sure
little beyond the
that the insulation
be trimmed
edges at
down
the ends
edgesof
comes
up
after the wire is
of the channel
can
thickness
of paper put on over
the first
the covering on the wire is liable to be
covering,as
the insulation ;
cut through at these points. Examine
if all right,
give it a thick coat of shellac and leave to
dry.
To wind the field-magnet
requiresabout 2 Ibs. of
No. 22 S.W.G.
singlecotton-covered copper wire,which
be wound, layerby layer,
by hand, in the direction
may
shown in Fig.136, keeping it as even
as
possiblewith
tension.
The
number
moderate
of layers is not
a
be finished either
important,and the winding may
at
the
top
or
bottom.
It
does
net
matter
greatly
DYNAMOS
140
if the number
same
;
but
try
of
to
ELECTRIC
AND
layerson
put about
it is essential
for
each
core
the
winding
Fig. 136, and kept
in
As each
finished it should
with
is not
1 Ib. of wire
direction shown
layeris
MOTORS.
sufficient shellac varnish
quite the
on
each
to
be
so
in
give
;
the
throughout.
be brushed
to
core
the
all
over
surface
a
good coat. The commencing ends of the wire B and A,
Fig. 136, which reach from the core outwards,should
be wrapped round
with
thin paper
along the part
which is buried in the end of the coil,
and varnished
with shellac to make sure that the current goes straight
to the innermost
layerand does not leak away to the
other layers. The current
must
go through the wire
from end to end without making a short cut across
at
while
any point. If a bare or frayed place is found
it with some
thin paper.
The most
winding, cover
convenient way
to wind the coils is to fix a stripof
wood to the top of the magnet by the terminal-board
to a face-plate
screws, and then to fasten the wood
fixed on
the lathe,bringing each
in turn
to
core
the centre.
If the weight of the overhangingcore
is
counterbalanced,the magnet will be rotated more
the
conveniently
face-plateround with the
; turn
left hand, guiding on the wire with the right hand,
the wire requirespassing
assisted by the left where
between
the
cores.
The
magnet
may
be made
with
a
joint through the top to allow of winding the coils in
all
if the jointis made to be in close contact
the lathe,
the
over
surface.
The
extra
trouble
taken
to
wind
nothing compared with extra
the jointand magnet in one
work needful to construct
Completelywind one core
piecein the way mentioned.
first to the full depth of the cheeks,and then proceed
the
ends
make
the
to
with the other, joining
Cover the last layer with two
final connections.
or
the coils
as
described
is
three coats of shellac varnish.
To wind
S.W.G.
armature
the armature
double
requiresabout J
cotton- covered
in the lathe between
copper
Ib. of No. 20
wire.
centres,with
Put
the
the
com-
DYNAMO
UNDERTYPE
MOTOR.
AND
141
from the rightrighthand. Commence
hand end and laythe wire from there,
alongthe channel
the end and underneath
to the left-hand end,then across
along the channel to the right-handend,across
the channel for one layer,then back again for second
and continue
layer. Get on as much wire as possible,
winding until the channel is quitefull
mutator
to the
Fig. 136."
Field
Magnets, showing
Each
layer"of
wire
varnish.
If found
more
channel
on
one
and then that
wind
on
should have
a
of
coat
Winding.
of shellac
the portionof
convenient,
the
side of the shaft may be filled up first
the other side. Having commenced
to
the wire round
direction must
Method
the
core
be maintained
in
this
direction,
rightthrough,as is shown
a
certain
the direction of
by Fig.25 (p.23). It is easy to reverse
the winding when passingfrom one side of the shaft to
and care must be taken to avoid this mistake.
the other,
DYNAMO
UNDERTYPE
The brushes
may
may
of sheet copper or of copper
to make
flexible,
good contact
with
a
wire
a
each 2
to
so
one
curve
made
and
from
brush-holders.
copper
wire, about
A
good
No.
24
vice,take hold of the other end
pairof pliersand give a fair pull,to stretch the
it. Cut off sufficient pieces,
littleand straighten
in. long,to make two brushes each J in. wide,and
end solder the wires together. It is a good plan
; fix one
S.W.G.
at
be
143
be made
wire ; they should
be
with
the commutator
brush
MOTOR.
AND
end in
the brush
a
where
it touches
that there is a surface of contact
the commutator,
about J in. broad all
along the brush.
The
dynamo is now
complete,but, to commence
with,itsfieldmagnet requires
exciting; afterwards itwill
always excite itself.The direction for running is that of
the hands of a clock,
when the observer looks at the side
of the pulleyas if lookingat a clock face. Rotate the
in this direction at a high speed ; if it sudarmature
denly
works stiffly
and sparks appear at the brushes,it
and the field magnet will not
has started itselfall right,
require any further assistance ; but if this does not
occur, and the dynamo fails to lighta 10-volt lamp, an
electric batterywill be requiredto give the field magnet
the necessary start. Put a pieceof paper between
one
of
the
brushes
and
the
goingthroughthe
commutator
to
prevent
the
Now, lookingfrom
the positivewire of a
the commutator
end, connect
and the negastrong batteryto the right-handterminal,
tive
wire to the left-hand terminal.
While
the batteiy
is thus connected,
gentlytap the iron of the field magnet
for half a minute ; disconnect the battery,
with a hammer
the paper from under the brush,and on driving
remove
the armature
again the machine should work all right.
The output of this dynamo, with 3,000 revolutions per
minute, is about 10 volts at 5 amperes ; but it will give
higher electro-motive forces up to about 20 volts with
if run
at higher speeds. The
less current
dynamo can
be paintedto suit taste.
current
armature.
144
CHAPTER
440- WATT
THE
MANCHESTER
described
dynamo
type, shunt
of 440
watts
at
"
XH.
TYPE
in this
wound,
and
viz. 8 amperes
DYNAMO.
chapteris of
designed for
at
55
1,800 revolutions per minute.
volts
"
the Manchester
an
output
when
Figs. 138
ning
run-
and
147)show a plan and an end view of
the machine complete.
The field magnet castingscan
be bought with the
tunnel bored
armature
out, 5^ in. diameter,and the
fitted. The base of each pedestalis
field magnet cores
in the
turned, making the centringof the armature
easier than when
tunnel much
a flat-bottomed
pedestal
139
(pp.145
is used.
5j
in.
and
The
long,
field magnet cores, 2f in. diameter
with 11 Ib. of No. 20
wound
are
and
S.W.G.
5^ Ib. being wound on each core.
direction of the winding is shown
in Fig. 141
The
(p.151),producinga north poleat the top and a south
pole at the bottom.
be fixed by
The
field-magnet bobbin ends may
turninga shoulder on each end and shrinkingon these
shoulders circular plates of iron ^ in. in thickness.
the bobbin end.s
But if unable to turn these shoulders,
of either sheet brass,
sheet vulcanite ^ in.
may be made
wood ends,procure
To make
thick,or thin hard wood.
eightsheets,each " in. thick,by 6 in. square, of any
hard
fretworkingwood, such as pear,
close-grained
Glue
pairs of the sheets together
holly, walnut.
with the grain of one
face to face,
running at right
them
angles to the grain of the other,and cramp
in a flat press for twenty-fourhours,thus making four
the four sheets together
sheets | in. thick. Then
screw
of a
them on the face-plate
at their corners, mount
lathe,and in the centre bore a hole to fit the magnet
cotton-covered
wire
"
TYPE
DYNAMO.
outside
to make
MANCHESTER
tightly.Turn the
diameter,and thus make
cores
The
cores
and
the bobbin
145
a
disc 5 in.
ends.
of the field magnet are drilled at each end,
in. A stud 3 in. long is screwed into one
tapped"
end,and in the other end placea hexagon-headedbolt
3 in. long. Centre the end of the stud and the bolt
head, and placethe core between the lathe centres to
Then paint the core
with
that it runs
true.
see
fairly
Brunswick
black,and, while wet, push the bobbin ends
and paintthem on the inside and round the joint.
on
be left clean and bright,
must
The ends of the cores
Fig. 138.
Plan
"
they will
otherwise
of Manchester
make
Dynamo.
joint with the poleof the dynamo.
efficiency
a
bad
and so lower the
pieces,
Winding the wire direct
on
force off the bobbin
Pieces of wood
and
5
ends.
in. square, with
both the stud and the
of the
cores
by
core
would
holes in the centre
tend
to
i in. thick
to pass
bolt,and pressedagainstthe
over
ends
i-in. nuts, will prevent this. The
two
be wound
the
evenlyby hand in the lathe,
using
slow speed. It should previously
be coiled,
and
a very
placed so that it may run freely; and can then be run
through the hand without causing kinks. An empty
wire
can
on
DYNAMOS
146
bobbin
ELECTRIC
AND
MOTORS.
held in the
palm of the hand, for the wire to
run
sore.
over, will avoid making the fingers
A coat of shellac varnish should be given each layer,
and allowed to dry ; then wind back, and so continue
until all the wire is wound
wound, put them
dry and
in
a
When
on.
both
placefor
warm
cores
are
few hours
a
to
harden.
The
is 5 in. diameter
wide,and
is built up of 150 soft iron cog-ringstampings,
having
channels
ten
and
1 in. wide
" in. deep. An
easy
method
of insulating
the laminations is to cut 150 sheets
armature
of tissue paper
paste a sheet
6 in. square,
each
on
and
and
with
stamping.
in.
4
shellac varnish
Then
thread
the
stampings togetherwith five brass rods J in. diameter
and 5 in. long,screwed each end for f in. Put washers
on the brass rods to equalthe thickness of the bosses on
the spiderarms, and screw
up the end nuts until the
is 4 in. wide,using the calipers
armature
to ascertain
that the end faces are parallel.
Fig.140 (p.149)shows a section through the spiders.
The outside is comparatively
and the inside has a
flat,
central boss
each
arm.
boss
on
also smaller
the end of the five
a
J-in.hole
spiderarms
between
may
the
ought to
to receive the
be bent
their
ends
of
bisect each
of each
of the brass
the
respective
holes,
by lightblows
with
a
hammer.
the armature, run it
the lathe centres,and adjustcentre dots placed
spidersare
bolted
the end
near
In the centre
arms.
If the rods do not enter
When
bosses
A circle 4j in. diameter
boss drill
rods.
and
on
spiderstillthe whole runs true. Having marked
take them off and bore a
the positionof the spiders,
|-in.hole in the central boss of each. Decide which
is going to be placed at Jthe commutator
one
end,and
in it file a keyway J in. wide and T% in. deep ; this
in the
should
be under
one
of the arms,
so
as
to weaken
the
spiderleast.
spindleis shown at Fig.140 (p.149); it ia
14| in. long,its collar being Ij in. by J in. The central
portionis \ in.diameter by 7| in. long,the journalsbeing
The
steel
MANCHESTER
DYNAMO.
TYPE
147
by 2" in. long. The keyway must bo cut
end " in. deep and J in. wide for a
at the commutator
length of 3" in. A keyway -^ in. wide and deep must
also be cut at the pulleyend.
The bearingsare of cast iron,
and their bases have
the same
radius as that of the armature
tunnel,the
bearingsteps being turned and the tunnel bored at the
wards
same
operation.The web of the bearing stands outwhen in position.Bore each bearingto take the
mutator
shaft,
and, at the inner side of the bearingat the comend, turn a shoulder Ij in. diameter and " in.
Q
in. diameter
nrn
rim.
Fig. 139."
wude
to
End
take the brush
View
of
rocker.
Dynamo.
In
the
top of each
"-in.gas-threadhole for a
the bearingstogether
lubricator. Mount
on
a mandrel,
and turn up their bases. They are fixed with |-in.
bolts.
be found by trying
The height for the bearingsmay
when
it is mounted
the shaft,
the armature
to see
on
that the air space is equalabove and below.
The cast-iron drivingpulley is 2" in. diameter by
It should be bored to f in.,
the face.
ij in. across
and fastened to the shaft with a key ^ in. wide.
The
depth of the slot in the pulley should be J in. This
key must have a head, so that it can be drawn when
required.
bearing drill
File
round
or
turn
and
tap
three grooves
the armature
explainedon
an
p. 54,
f in. wide
stampings,to
one
groove
and
"fain. deep
take bindingwire,as
in the
centre
and
the
DYNAMOS
148
other
two
ELECTRIC
AND
each
in. from
1
end
MOTORS.
of
the
armature.
Sinking the binding wire into the iron core allows a
and gives a small air
margin for wear in the bearings,
the machine more
efficient.
space, thus tendingto make
all sharpcorners
from the armature,
remove
Carefully
if the stampings cut the insulation of the wire the
as
whole coil has to be unwound, the insulation repaired,
and finally
the coil rewound, which
take hours
may
to
should
complete. The whole of the armature
have a coating of shellac varnish.
When
now
an
assistant is to help wind
the armature, the shaft
and spidersare removed
laid on a trestle
; it is then
held firmly down
and
by a strip of wood passed
For a single-handed
through the core.
job, fasten it
down to a table,
as shown
on
p. 68, so that it will thus
to work at it sideways,
be possible
and get at each end.
Before winding the wire the channels must be covered
with paraffin-soaked
tape,one layerbeing sufficient; as a
further protection,
of narrow
extra strip
an
tape may be
put
across
each of the
corners.
of 5 Ib. of No. 17 S.W.G. doublewire,consisting
be divided into ten equal lengths.
must
cotton-covered,
The
To do
45 ft.
this,fix
apart ; then fasten
and wind
short
should
or
one
whole
and
measure
a
forwards
coil is unwound.
consist of ten
over,
at
distance of
end of the coil to
the wire backwards
reel until the
wound
empty cotton-reels
two
one
round
The
reel,
each
wire
so
but if there is any
lengths,
shift the reels apart so
the two
in ten turns round
it and
that all the wire is used
they pass round the
and produce ten equal lengths. By placingthe
reels,
reels at half the distance apart and cuttingat one end
Each length
result is to be obtained.
only,the same
soaked in melted paraffin
be looselycoiled,
must
wax,
reels. Then
and allowed
the wires where
cut
to drain and
harden.
Proceed
to wind
one
24 in. long,l" in. wide,
shuttle,
out like a
and \ in. thick, the ends being hollowed
butcher's tray (seeFig.58, p. 62). Cut from hard wood
ten pieces,
$ in. square and 1| in. long,with a J-in hole
of these coils on
a
wooden
MANCHESTER
drilled
f in. from the
TYPE
of each
end
DYNAMO.
and
piece,
149
them
secure
rods,as shown at A, in Fig.141
The enda
(p.151),to take the placeof the spiderarms.
of the coils are kept in position
by these,and the wire
when
is preventedfrom gettingunder the spiderarms
they are beingplacedon to the ends of the armature.
is in positionfor winding,
When
the armature
take the shuttle of wire,cut the insulation off the end
to the ends of the brass
for
a
distance of 1 in. or
so, and
it to the bench
secure
the wire into the channel
Wind
by bringing
the shuttle over
the armature, and passingit back
throughit,startingat the left-hand side (when looking
at the commutator
end),winding to the rightand then
by
a
screw.
Fig. 140.
back
againto
"
LongitudinalSection
the
shuttle is wound
risht-hand side.
and
left,
on
the
at
armature, finishing
the
the
Beat
Dynamo.
on
on
so
the
of
tillall the wire
wire
regularby
a
small
mallet,or by a piece of wood struck with a
The bulging of the wire on the inside is apt
hammer.
for carefully
be watched
but must
to be overlooked,
;
when pushing the shaft through the armature,
otherwise,
it may
damage the insulation. A galvanometershould
the latter.
for testing
be used,if possible,
this coil is completelywound, 3 in. being left
When
wooden
to
connect
to
the
to
the
commutator
wire,wrap
a
band
as
a
tion
temporary protec-
of calico round
the
coil,
securingit with thread ; then proceedto wind the other
coil must
coils similarly.The commencing end of one
be soldered to the finishing
end of
end of the next,one
MANCHESTER
be
must
screws
TYPE
placed.
DYNAMO.
151
strip,on the latter
that on the extreme
drilled,
In each
line,three holes must be
beingT\ in. tapping; the next ^ in. away, and
left,
the extreme
on
being both countersunk
third,
right,
a
Hn. brass
screw.
When
all the holes
are
the
for
drilled and
tapped,fileaway all burrs and lumps from the inside of
the casting,
observingthat the button-headed
screws,
which are fitted to the TVin. tappedholes,
do not project
inside the cylinder
when screwed down to the head.
Warm
the castingwhile melting some
glue,which
should be thin,so as to have a close joint. Then drive
in the short pieceof boxwood, parted face first,
until
flush with the end of the brass cylinder
; put a little
Fig. lil."
glue on
the
End
View showing: Method
Armature
and Fields.
parted face
of
Winding
of the other
and drive it
piece,
into the open end with a mallet,
so that the grainof the
is at rightangleswhen theymeet in the centre
two pieces
of the brass casting.Directlythe wood is driven home
placethe whole endways between the jaws of the vice,
and keep it under pressure
for some
hours.
If the
uniform
the cylinder,
across
screws
grain were
some
the commutator
fastening
stripswould be apt to strip;
but with the grainat rightanglesone
is sure
to
screw
hold.
all the
gluedjointis set quitehard,screw
brass holding-down screws
into their respective
holes;
then with a hack saw
cut through the casting
alongthe
When
the
DYNAMOS
152
lines
than
alreadydrawn, taking care
all the
are
strips
and clean away
singly,
of mica in the saw
put strips
by screwingthe commutator
to
put
The
hole
etc. ; then
filings,
cuts,and jam them tight,
striphome, but be careful
that
so
screws,
chuck when
not to
it is
Pig. 142."
ebonite
but
shaft,
boxwood.
may
too
be
commutator
key,fitted
which
need
When
the
Brash
this
ing
work-
and
large,
impossibleto try
held
Bore
central hole.
get it
button-
it in
place.
is sufficient to force the commutator
pressure
place. The
screws.
carryingthe
the commutator
boring the
takingcare
| in.,
Hand
the brass
on
the end
at
projects
as
by calipers,
or
deeper
saw
all brass
great a strain
too
boxwood
headed
a
to
apart,lifteach alternate
sawn
one,
in
not
-fain. into the boxwood.
When
not
MOTORS.
ELECTRIC
AND
into
Gear.
be driven
by a vulcanite
into the existingkeyway in the
than \ in. into the
more
go no
must
commutator
is mounted
on
the
turn it up in the lathe,
using a fine-pointed
shaft,
tool,
then
finish
cut
with
and taking a very light
fine
;
up
not emery-cloth.
glass-paper,
The
brush
rocker
and
brush
gear
are
shown
at
Fig. 139 (p. 147),with the rocker fitted to the bearing,
togetherwith one brush and brush-holder. The brass
rods to carry the holders are \ in. in diameter by l" in.
long, turned down to f in. for another \\ in.,and
for " in. at the small end.
screwed
Fig. 140 (p.149)
with a vulcanshows a half section of the brush rocker,
ised
fibre bush
Fig. 142A
and washers
is
a
section
at each end.
showing
an
easy
method
of
the pressure
regulating
of
by means
The
width
of the brushes
the
the lower
at
DYNAMO.
TYPE
MANCHESTER
pieceof
end
153
the
upon
mutator
com-
spring steel.
piece of steel in
thin
of this
exactly that of the space between the cheeks of the
when the stripof steel is secured
brush-holder,
therefore,
to the ^brasssupportingrod by the small steel screw,
there is no side-play
in the brush-holder.
The other
end of the steel stripis J in. wide and 3| in. long,with
soldered to it,
and has a ^ in. thumb-screw.
The
a nut
shown in plan at B, is about 4j in. long,over all.
spring,
The brushes are held off the commutator
by means
in position
of the steel tongue shown
at A, and also in
detail at
c.
end of this tongue, which is bent round at right
angles,must be secured to the holder by a TVin. screw,
The
the other end
brush
having a
Q
is off the commutator
head of the cheese-head
head
partlyfiled
this hole
screw, which
down
that when
-shapedhole,so
to
drops over
must
receive it.
the
the
have half its
To
release the
brush the tongue must
be lifted with the finger
off the
The
screw-head.
largersteel spring,through which
this tongue passes, then presses the brush on the commutator
with a pressure that can
be adjustedby means
of the thumb-screw
of sheet steel
thumb-screw
placed on
wide
the end
as
of the
the brush
spring. A piece
is fixed
so
that the
againstit,and a similar piece is
top of the brush, extendingfrom the
presses
the
brush-holder
When
as
at
to the toe of the brush.
the
machine
is
to the
ready
it by a
for
secure
trial,
If-in.belt to
it
the
floor,and connect
end of the
driving-power.Looking at the commutator
run
clockwise,with the brushes
armature, it must
and pointingin the direction of
diametrically
opposite,
rotation.
hand
Connect
the end
of the last coil of the left-
field magnet to the left-hand
brush,and the last or
outside coil end of the right-handfield magnet to the
right-handbrush,the two ends of the bottom layersof
each field-magnet
coil being joined together. Next
the positive
connect
pole of a set of four Leclanchtf or
DYNAMOS
154
three
bichromate
AND
cells to
ELECTRIC
the
MOTORS.
left hand
brush,and
the
One
of these
right-handbrush.
wires must
be cut with clean ends, so that they can,
when brought in contact, complete the circuit.
Hold
the two
ends of this wire in the hand, and
negative pole
run
the machine
to
the
at about
1,800 revolutions
per minute
;
then,when fullyunder way, touch the two ends of the
wires together. If the batteries are in good condition,
they ought to be strong enough to start the magnetism
in the field magnets.
If the dynamo begins to excite,
the first thing that will be noticed is that the tone
will change from a
given out by the revolvingarmature
whirr to a low humming
sound ; sparks also will be
observed
at the brushes.
Directlythe machine starts to
and
the battery circuit,
excite, disconnect
keep the
Then
machine
stop and
running for a few minutes.
50-volt 16-candle-power or 8-candle-power
connect
a
venient
lamp to the brush-holders by two wires of any conlength. Run the machine
again,and the lamp
ought to lightup when running at 1,800 revolutions per
If the machine
will not excite the first time,
minute.
the leads from the field magnets to the brushes,so
cross
with the leftthat the right-hand brush is connected
hand coil and the left-hand brush with the right-hand
coil ; then
the machine
run
again,and if unsuccessful,
try six, then eight,batteries in series to excite the
there is a broken
field magnets; if still unsuccessful,
wire,or the insulation has given way in the armature.
This must be discovered and repaired. Then connect
up
six more
lamps of 16 candle-power each, one by one as
is running,and if the brushes start sparkthe machine
ing,
of the rocker,
bring them slowly forward,by means
in the direction of rotation until the sparking ceases.
The power
required to drive the machine, when under
full load,will be about " brake horse-power.
Not
until the machine
works
properly should the
touches be put on.
finishing
INDEX.
18,25
Armatures, Laminated,
Ampere,
114
of, 14
B
of, 14, 76
Armature, Meaning
,
Shuttle
Double
,
Primary, for Lighting,
in
Localising Faults
Dynamo,
130
Motor,
111
for
Undertype
for 50-watt
9
Battery for Driving Model
17
Walker,
or
76
Drum,
,
146
Winding,
Lights, etc., 10
for Night
Batteries
Pacinotti, 17
or
,
,
Repulsion of PoK.-s,
and
Attraction
Meaning of, 13
hour, Meaning
,
89
Dynamos,
Cogged King
Used, 77
Ring, When
,
of Small
Ailments
namos,
Dy-
89
72
Bearings of Simplex Armature,
for Winding,
Fixing to Bench
,
"
of Manchester
147
Dynamo,
71
Bed-plateof Simplex Dynamo,
Building
Gramme,
,
44
of Undertype
for Winding.
Preparing
,
up,
47
Insulating, 67
,
,
of Winding,
Method
,
for Model
84, 148
Electro-motor,
Ends
Broken
Wires, Joining,
100, Brushes,
50-watt
Magnets,
144
20
Uudertype
namo,
Dy-
135, 143
of Motor, Preparing, 121
Winding,
,
King, 76
,
Shuttle, 17, 18, 77
of Model
Position
,
of
.Siemens H-girder,21, 25
,
,
Testing, 27
,
,
Winding,
of Simplex
of Manchester
125
,
33
Dynamo,
66
Classes
ot, 15, 76
Dynamos,
153
Electro-motor, 102
of, 94
Shuttle
Motor,
Armature
128
of Siemens
Dynamo,
29, 31
of Simplex
Dynamo,
73
.Sparking
Brush-holder
Speed of, 83
Armatures,
of Field
Bobbin
lOt, 110
,
of,70
Wires, Use
Winding, 148
,
,
IS
Screws, 18, 110
63, 146
Manchester,
74
Belt of Simplex Dynamo,
Binding Posts,
91
Dynamc,
at
the, 95
of Gramme
Dynamo,
DYNAMOS
'56
Brush-holder
ELECTRIC
AND
MOTORS.
of Motor, 124
of Siemens
Dynamo,
of Simplex
Dynamo,
30
Discs, Preparing,131
73
Driving Pulley of Crypto Dynamo,
138
Dummy
Armature
and
Shaft, Use
of, 130
Dynamo
for
Charging
Accumula
tors,90
Wire
Calculating
required
for
Definition
,
Armature, 51
of Dynam
Care
for Electro-depositing,
90
js, 97
50-watt
,
Castings, Cost of,22
129
41
42
Dynamo,
Invention
,
Rough, Trueing-up,22
for
Undertype,
Gramme,
"
of Gramme
,
of,10
for
Shuttle-Armature
Motor,
of,9
Pour
Lighting
10-c.-p
Lamps, 75
120
to Light Two
Clamp for Armature
Core, 68
,
Manchester, 144
,
Model, Type of Armature
,
Siemens,
,
Simplex, 66
for Holding Brushes, 56
Classification of Dynamos,
of
Commutator
8-c.-p.Lamps,
66
ton
9
77
Crypto
Dynamo,
21
"
134
Firing
,
Shaft, 31
to
Dynamos,
Dynamo,
of Gramme
"
of Manchester
of Model
Dynamo,
Electro
Classification of, 9
49
150
Motor, 102,
124
Dynamo,
27
of Simplex Dynamo,
70
of Siemens
Electrical
Winding, 40, 65
of Dynamos,
Connecting Wires
Current, Explanation
of
10
for,89
Compass, Substitute
Compound
Electric
Energy, Effects of, 11
Measurements,
39,
Electro
Motor
Engine
to
153
Connections, Accidental, 93
13
(See Motor)
Develop i Horse-power
66
Connectors, 18
Contact
Experimenting
Breaker, 110
with
Motors,
118
Spring, 109
Cost
of Dynamo
Current
from
Castings, 22
Dynamo,
How
lated,
Calcu-
80
,
How
Determined, 76, Faults
in
79
Currents, Directions
Magnets,113
of
in
Bar
in Dynamos,
Winding,
Localising,89
31
Field Magnets. Castings of.1?,0,
130,
141
INDRX.
Segments,
nsulating Commutator
Magnets, Compound- Wound,
Field
'57
27,50
65
of
Undertype
50-watt
usulation,Defective,93
139
Dynamo,
Varnishes, 83
"
12,
Dynamo,
of Gramme
44,57
,
,
Length of Cores
of,82
of Manchester
Dynamo,
oining Wires, 67
12,63
of Model
Motors, 98
Overtype,
,
11
of Siemens
12,71
Simplex Dynamo,
of
Armatures, 18,25
laminated
22
Dynamo,
,
Types of, 11
,
Winding, 35, 57, 126,139,
Laws
Governing Electro-motors.
Lead
of Brushes, 32, 83
IIS
.kage,Discovering, 92
91
in Dynamos,
144, 145
ghting, Electric (SeeBatteries and
"
Undertype, 11, 139
,
Dynamos)
Fifty-WattUndertype Dynamo
and
Dynamo,
for Gramme
Lubricator
47
Motor, 129
Finishing Simpler Dynamo,
for
Former
Winding
74
Armature
of
Neutralised, 91
Magnetism
66
Simplex Dynamo,
of,90
Want
,
Magnets, Poles of,10,37, 112
,
61, 144
Dynamo,
Manchester
Galvanometer, Cost of, 34
Outputs
and
Dimensions
of,34,93, 149
Use
of,64
41
Dynamo,
Gramme
,
Dimensions
and
,
Output
to Drive
,
Horse-power to Drive, CO
over
Gap, 91
Armature
Small
with
Driven
35
Electrical,13
Measurements,
of,59
Guard
Winding,
Lathe,
Two
119
Batteries,118
Motor, 50-watt Undertype, 129
Model, made without Castings,
H
Handle
for Moving
Rocker, 56
Shuttle
"
,
Heating, Excessive, 95
,
Horse-power to Drive
Gramme
73
of
Simple* Dyt
Magnet
Small, with Horseshoe
Ohm,
Saddle, 107
Wooden
Mounting
Brushes
119
Dy
and
InsulatingArmature, 67
Armature,
Motor, 128
Meaning
Oil Guards
Dynamo,
of, 14
for 50-watt
135
Undertypy
INDEX.
Win-ling
Field
Gramme
159
Dead
Wire,
Maguets,
57
and
Joining,
Active,
77
67
,
Manchester
Field
Siemens
148
Armature,
Armature,
Laminated
Cog-ring
Calculating
145
144,
Magnets,
for
for
Preparing,
33
Length
ture,
Arma-
of,
Winding,
87
35,84,
,
Simple*
Of
Armature,
Sories
148
66
Motors,
Protecting,
115
83
,
Wire,
Broken,
Armature,
Safe
95
Carrying
Capacity
of,
79
,
for
Armature,
Cheap,
Calculating,
Disadvantages
for
51
of,
81
Shuttle
lating
Calcu-
Armature,
of,
Length
85
,
Circumferential
Velocity
for
of,
Small
lating,
Calcu-
Dynamos,
,
78
76
Copper,
.
Properties
of.
78
Wooden
Slab
for
Dynamo,
38
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BY
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'
ENGINEER,
ROPER,
of High-Pressure
Steam-Engines,"
or
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of the
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Locomotive,"
Roper's Hand-Book
of Modern
and
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Roper's Hand-Book
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"
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AND
EDWIN
BY
ENLARGED
GREATLY
B.
etc.
EDITION.
FIFTEENTH
REVISED
F\gineers,"
E.,
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KELLER,
AND
W.
CLAYTON
Ex-President
of ttte Electrical
Section
of
the Franklin
PHILADELPHIA
:
McKAY,
DAVID
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PIKE,
MARKET
1903.
STREET.
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