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Патент USA US2114853

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April 19, 1938.
A. J. MCMASTER ET AL
.
‘2,114,853
GALVANOMETER RELAY
Filed Sept. 5, 1936
4 Sheets-Sheet l
April 19, 1938.
A. J. MCMASTER ET AL
2,114,853
GALVANOMETER RELAY
Filed Sept. 5, 1936
4 Sheets-Sheet 2
April 19, 1938.
‘A, J. MCMA'STER ET‘ AL
GALVANOMET'ER RELAY
Filed Saint. 5, 1956
I;
V,
,
l
“I
/
2,114,853
‘
4 Sheets-She'et a
April 19, 1938.
A. J. McMASTER ET AL
2,1 14,853
GALVANOMETER RELAY
Filed Sept. 5, 1936
4 Sheets-Sheet‘4
Patented Apr. 19, 1938
2,114,853
UNITED STATES PATENT QFFECE
2,114,853
GALVANOMETER RELAY
Archie J. McMaster, Highland Park, and Walter
Van Guilder, Oak Park, Ill., assignors to G-M
Laboratories, Inc., Chicago, 111., a corporation
of Illinois
Application September 5, 1936, Serial No. 99,672
22 Claims. (Cl. ZOO-56)
The present invention relates generally to elec
exterior of a relay embodying the present inven
tric relays and more particularly to relays which tion;
are highly sensitive in that they require only
Fig. 2 is a general view in perspective of the
very small amounts of power for controlling
internal mechanism of the device illustrated in
them.
The relay of the present invention comprises
Fig. 1;
a taut suspension D’Arsonval galvanometer
movement and a clamping and contact operat
pieces and partial assemblies of the apparatus
of Figure 2 individually in perspective;
ing mechanism adapted to clamp a pointer carried
=10 by the galvanometer coil. The galvanometer
Figs. 4 and 5 are horizontal and vertical sec
tions respectively of the device of Fig. 1, Fig. 4
Contacts are operated each time that the pointer
being a section taken along the line 4—4 of Fig. 10
5, and Fig. 5 being a section taken along the line
5-5 of Fig. 4;
Fig. 6 is an elevation partly in section taken
along the line 6—6 of Fig. 5;
Fig. 7 is a section taken along the line l-—'! 15
is caught between the clamping jaws.
of Fig. 5;
movement, in response to the control current in
its coil moves its pointer into or out of the po
sition in which it may be engaged by the clamp
ing jaws or bars, and the clamping mechanism
periodically attempts to clamp the pointer.
The relay of the present invention employs a
plurality of independent contacts operated by
20 separate clamping jaws or bars which are dis
posed at various positions along the arc of travel
of the galvanometer pointer. It includes also
mechanisms for conveniently moving or adjust
ing the clamping jaws along the path of travel
Fig. 8 is a section taken along the line 8--8
of Fig. 6;
Fig. 9 is a partial view showing the apparatus
20
of Fig. 4 in a diiferent operated position; and,
Fig. 10 is an enlarged sectional detail taken
along the line lll—lil of Fig. 4.
The apparatus illustrated in Fig. 2 includes
of the galvanometer pointer so as to vary the
a D’Arsonval galvanorneter and a contact mak
values of control current at which the pointer
encounters or escapes particular clamping jaws.
ing mechanism controlled by the galvanometer. 25
any adjustment of the jaws while they are in a
The galvanometer itself comprises a die-casting
ID of non-magnetic material such as a zinc alloy.
(See Figs. 3, 4 and 5.) The die casing It] serves
clamping attitude with respect to the pointer.
as a housing as Well as a supporting frame for
- The adjusting mechanism is arranged to prevent
The invention further provides means for in
dica'ting visually on a graduated scale both the
de?ection of the galvanometer needle and the
adjusted position of the clamping members.
' The present invention further provides new
and novel mechanisms for providing the oper
ations and functions mentioned and described
above.
t is an object of the present invention to pro
vide an improved relay of the type indicated,
which is rugged and reliable and otherwise suit
able for use in industrial control apparatus.
It is a further object of the present invention
to provide improved apparatus for performing the
above described functions.
Theseand other objects and advantages of
the present invention will become apparent as
the description proceeds.
The following description of a speci?c embod
iment of the present invention, when taken in
connection with the accompanying drawings will
enable those skilled in the art readily to under
stand the invention and to practice the same.
In the drawings:
55
Fig. 3 is an exploded view showing some of the
Fig. 1 is a general view in perspective of the
a portion of the galvanometer apparatus. A 30
pair of iron pole pieces ii and i2 (Fig. 3) are
imbedded in the die-casting l0 and each pole
piece extends from the exterior of the casting or
housing In entirely through the wall thereof
into the interior cavity thereof. Preferably, the 35
pole pieces II and 12 are placed in the mold at
the time the die-casting I8 is struck so that the
casting is formed about the pole pieces II and
!2. The pole pieces conveniently may have ir
regular surfaces such as identations l4 shown
in the section of Fig. 8 into which the metal of
40
the die casting may flow for securely locking
the pole pieces in position.
Supported on a boss it of the die-casting I!) 45
(Fig. 5) is a core l5 positioned between the two
interior faces of the pole pieces H and I2 so as to
provide two air gaps as shown in Figs. 3 and 8.
Like the pole pieces H and l2, the core l5 is of
iron or similar magnetic material. A magnet 50
26 (Figs. 2 and 5) completes the magnetic cir
cuit and provides the magnetic ?ux in the two
gaps already mentioned.
A coil IT is supported on two taut suspension
wires I8 and 19 which in turn are supported on 55
2
2,114,853
resilient metal tabs 2| and 22 (Figs. 3 and 5).
These tabs 2| and 22 in turn are supported on
insulating. disks 23 and 24 which are directly
supported by the die-casting
ill. The loop
shaped coil H has one of its sides lying in each
of the air gaps provided between the core 55
and the pole pieces H and i2. A pair of non
magnetic plates 2? and
(Figs. 3, 5 and 8) are
placed over the core l5 and cover the two mag
10 netic gaps near the tips of the pole pieces | | and
room to swing from side to side within the en
closure as the coil |'| rotates.
A pair of terminal screws 43 and 44 (Fig. 5)
are secured to the casting ID with insulating
washers.
These terminal screws are connected
to the spring tabs 2| and 22 to provide electrical
connections to the coil ll of the galvanometer.
The wire 45 connecting the terminal 23 to the
upper tab 2| extends from the tab 2| down
through the hole in the disk 23, then down along 10
i2 so as to con?ne and protect the coil ill.
The two suspension wires l8 and I9 consist
of very ?ne gold ribbon or the like, and the-y are
held taut by the resilient tabs 2| and 22. The
resilient tabs 2| and 22 support these ribbon sus
pensions |8 and 19 at the center of the disks 23
and 24 so that the axis of rotation of the coil l7
coincides with the centers of the disks 23 and 24.
the interior wall of the casting l0, passing be
tween the wall of the casting l0 and the guard
plate 28 at one side of the boss l6, all to avoid
touching the suspension | 8, the coil IT, or the
15
wire 35 which carries the counterweight 4 |.
A galvanometer ‘front plate 46 (Figs. 5, 6
The suspension wires l8 and 53 not only support
an opening at the front near the top where the
pointer 36 emerges. The plate 46 includes a tab 20
or tail 4? which hooks under the U portion of the
20 the coil l'i mechanically but they also serve as the
electrical connections thereto, the adjacent ends
of the wires l8 and |9 being connected tothe
winding of the coil H for this purpose. The
torsion of these wires provides the restoring force
25 of the coil. Each of the two insulating disks 23
and 24 is rotatably adjustable in the casting it)
for setting and adjusting the rest or Zero posi~
tion of the coil |'|.
As best may be seen in Figs. 3 and 7, the upper
30 disk 23 is notched and this notch is adapted to
engage an internal projection ill of a rotatable
cap 32. This cap 32 ?ts onto the die-casting II]
and rotates thereon about an axis substantially
concentric with the center of the disk 23. The
projection 3| of the cap is adapted to engage
shoulder faces 32 of the casting l0 so as to limit
the angle through which the disk 23 may be ro
tated. The cap 32 is adapted to be rotated man
ually by the users of the instrument so as to
40 permit manual rotation of disc 23 for correcting
the zero position of the coil IT. The limited
angle of rotation prevents the user from care
lessly or accidentally rotating the disc 23 contin
uously in one direction to thereby damage the
suspension wire l8 by twisting it excessively.
The disk 24 also rotates in the casting Hi. This
disk is not provided with any stops for limiting
and 7) ?ts over the die-casting Ill so as to close
entirely the bottom and front thereof except for
magnet 26 for supporting the weight thereof and
for holding the magnet in position on the pole
pieces H and I2. The plate 46 also includes
lateral projections 48, 49, 50 and 5| which sup 25
port the magnet at the front. A bar 53 secured
to the back of the die-casting I0 supports the
magnet at the back and clamps it against the
projections 48, 49, 5|] and 5|.
The front plate 46 also supports an electric 30
motor 55 (see Figs. 2 and 5) and a bell crank
57, (see Figs. 3, 5 and 6) which constitute a part
of the clamping and contact operating equip—
ment. The electric motor 55 preferably is of a
type which operates on alternating current and
employs shading coils for obtaining a magnetic
phase displacement which in turn produces the
effect of a rotating magnetic ?eld for turning the
rotor. The motor includes coils 60, a magnetic
?eld structure 6|, shading coils 62, and an en 40
closed rotor structure 63. The rotor structure
63 includes a reduction gear (not illustrated in
detail).
The single shaft 64 extending from the
reduction gear turns at a slow speed, such as,
for example, a speed of one revolution per min .45
ute. The shaft 64 carries a cam 65 which oper
ates the bell crank 5'|. Thus the motor lifts the
its rotation because it is not accessible for ad
clamping mechanism through the bell crank 51
justment unless the device is partially disman
once each minute.
tled.
It is intended to be used only as a factory
adjustment.
Secured to the top of the coil ii is a piece
of formed non-magnetic wire 35 (see Fig. 5).
One end of this wire extends upwards substan
tially parallel to, alongside and in front of the
upper suspension wire l8 and bends forward at a
right angle for receiving a pointer 36, which con
sists of a thin-wall aluminum tube. This tube
carries a small ?ber bushing 3'3 near the outer
end thereof to protect it and prevent it from
collapsing under the mechanical force of the
clamping mechanism to be described presently.
The extreme end of the pointer 36 is collapsed
for bending it and also for providing a blade like
65 portion 38 for cooperating with a visual scale
39. (See Figs. 2, 3 and 5). The other end of
the wire 35 (see Fig. 5) extends back from the
coil IT at right angles to the suspension wire |8,
that is, in a direction opposite to that of the
70 pointer 36 and its bushing 31. It extends
through an aperture in the main galvanometer
die-casting It) and carries at its end a counter
weight M for balancing the weight of the pointer
36 and its bushing 31. A box-like cover 42 closes
75 this aperture and gives the counter-weight 4|
Referring particularly to Fig. 2, the clamping 50
mechanism includes a pair of clamp bars ‘H and
32 which are adapted to be raised periodically by
the electric motor 55. These clamp bars are
arcuate in contour and lie under the path of
travel of the bushing 31 on the pointer 36. Above 55
the bushing 31 is an arcuate stationary bar 13
against which the bushing 31 is adapted to be
pressed by the bars 1| and 12. The galvanom
eter structure including the pointer 36 as well
as the resilient tabs 2| and 22 which support V60
the taut suspension wires l8 and I9 (see Fig. 5)
are suf?ciently resilient to permit the pointer 36
to be moved this slight distance to be brought
into engagement with the bar 13. Quite obvi
ously, the bushing 31 normally must lie a small 65
distance removed from the upper, or stationary,
bar 13 because it can not be permitted to touch
the bar 73 at the time that it is required to move
under force of the current in the coil IT or under
the restoring force of the suspension wires l8
and I9.
The separate clamp bars ‘H and 12 have
separate contacts 14 and '55 associated with them
which they are adapted to operate. A clamp bar
operates its contacts only when it catches the
3
2,114,853
pointer between it and the bar ‘I3 as it is raised
by the motor 55. The arcuate clamp bars ‘II
and ‘I2 are separated by a slight gap sufficient to
receive the bushing 31 and thereby permit the
pointer 36 and its bushing 31 simultaneously to
escape both bars. The two clamp bars ‘II and
‘I2 are adapted to be rotated about the axis of
rotation of the pointer 36 so as to permit the gap
between the arcuate clamp portions ‘H and ‘I2 to
10 be set at any position along the path of travel
of the bushing 31 carried by the pointer 36.
the pointer occupies a position at either side
this gap at the time the clamp bars TI and
are raised by the motor '55, it will be caught
If
of
72
by
one of the bars so as to cause that clamp bar to
operate its contacts.
The construction of the individual parts of the
clamping and contact making mechanism may be
seen best in the exploded view of Figure 3.
20
Referring to Figs. 3, 4 and 5, a ring shaped
rocker ‘I6 is pivoted, by means of pins which are
fastened in the rocker ‘IE, to the die-casting W at
‘IT and ‘I8 where the casting is given extra section
for that purpose. These two pins which carry
25 the rocker "I6 lie on an axis which is substantially
perpendicular to the axis about which the coil ET
rotates and which also is substantially perpen
dicular to the pointer when the same is in its
median position in its limited arc of motion. A
30 pair of arms depending from the rocker 16 at its
forward side, and at a position removed from the
axis of its support on the casting I0, carry a
35
‘I6 and frictionally to restrain rotation of the
ring 8| on the rocker "IS.
The ring SI carries a pair of clamp frames 83
and 84 which are secured to projections 85 and
85 thereof by means of pins such as pin 81, the
frames 33 and 8d being free to swing up and down
about these pins through a considerable angle.
These frames 80 and 84 include the arcuate
clamp bars ‘Ii and ‘I2 already referred to. Ex
tending under the clamp frames 83 and 84 are 10
contact structures which include the contacts 14
and '25 already referred to.
The details of the contact structure may be
seen best
Fig. 16 which is an enlarged sectional
view of the contact structure ‘I4 associated with 15
the clamp frame 83‘. A portion 89 of the ring
extends out below and between the projections
85 and under the clamp frame 83. A sheet of
fiber 9i somewhat wider than the portion 89 of
the ring 8i is Wrapped about the portion 89 and 20
the contact assembly is attached under it, the
parts being added in the following order: Re
silient contact blade 92, a terminal piece 93, an
insulator 9K1, resilient contact blade 95, terminal
piece 526 and a capping plate 91. A capping plate 25
similar to plate 91 is also placed over that
portion of the ?ber piece 9! which lies above the
extension 89 of the ring 8!. A pair of insulating
bushings iiii extend through the entire assembly
excepting only the two capping plates 97 and 90. 30
A pair of rivets !02 extend through the entire as
sembly for holding it together.
The wide piece
roller ‘I9 which is engaged by one arm of a bell
of fiber 9! extends beyond the several contact
crank 51.
The bell crank 51 is journaled on the ga1~
vanometer front plate 46 at a position to one side
ieces and also beyond the piece 89 of the ring SI
for the purpose of providing the large electrical 35
clearances required in industrial apparatus for
circuits of commercial voltages such as, for ex
ample, 230 volts. The structure just described
supports the two resilient contact blades 92 and
95 on the ring 8!‘ and insulates the ring BI and
each of the separate contact blades 92 and 95 40
from each other. The blades 92 and 95 carry
contact buttons at their ends which are adapted
of the roller 19 and off the axis of the slow speed
shaft 64 of the motor 55.
The cam 65 carried
by the shaft 64 engages the bell crank 5'! and
40 slowly oscillates it. The crank 51 in turn oscil
lates the rocker ‘I6 by periodically lifting and
lowering its forward side through the engagement
.with the roller 19. The weight of the clamping
apparatus carried by the rocker ‘IE (to be de
45 scribed presently) provides a restoring force for
maintaining the roller 19 in engagement with the
crank 51 and also for maintaining the crank in
engagement with the cam 65. If desired. spring
may be added to the mechanism for increasing
this restoring force.
The rocker ‘I6 includes on its periphery a circu~
lar seat for a ring 8I which is adapted to rotate
thereon. The center about which the ring SI
rotates on the rocker ‘I0 is substantially coinci
dent with the center of rotation of the coil ii,
to engage each other so as to constitute the con
taste “it already mentioned.
The clamp-frame 33 being pivoted at 81 rests 45
on the contact blade 92 so that its weight is sup
ported thereby. The tension of the blade 92 must
be sufficient to support ?rmly the frame 83; and
the spring 02 must be adjusted to bring the
arcuate clamp bar ll of the frame 83 slightly be 50
low bushing 3'! on the pointer 36 when the entire
contact assembly has been dropped to its low posi
tion by the motor 55. The blade 95 is adjusted so
that its contact is spaced slightly from the con—
65
that is, the position of the suspension wires I8
tacts of the blade 92 and so that when the con
and I9, when the rocker 16 is in a level position.
The ring 8! has teeth 82 (see Figs. 3 and 4)
formed in its periphery so as to face approximate
ly upward. These teeth are adapted to engage
tact assembly is raised by the motor 55 and the
bar it engages the bushing 37 on the pointer 36
and presses it against the bar ‘53, the contacts will
be brought into engagement, A similar contact 60
assembly is associated with the clamp frame 84
its arcuate clamp bar 12.
A cover IE5 is secured to side extensions I06
and if}? of the main die casting IS, the cover I05
being provided with bosses I09 and I I0 for that‘ 65
a screw or worm I I4 located just above it at the
rear portion of the ring 3| (see Figs. 4 and 5) so
that the ring 8| may be rotated on the rocker iii
in a manner to be described more fully presently,
and so that the teeth 82 may disengage the worm
l 94 in a manner also to be described. The rocker
‘I6 and the ring 8i are notched at their front
portions to permit their being put in place on the
die casting I0 or removed therefrom While the
70 pointer 36 of the galvanoineter is in place there~
by facilitating assembly. A pair of resilient clips
I02, one of which is shown in each of the Figs.
3 and 4, are secured to the top of the rocker
‘I6. They engage the upper surface of the ring 8|
1.75 to hold it in assembled relation with the rocker
purpose (Fig. <2).
The cover I05 is molded of a
condensation product but may be die-cast of
metal. The cover 105 has an aperture through
which the cap 32 extends, and the cover I05 ?ts
over a rim Hi of the cap 32 to retain it in place 70
atop the main die casting I0. The cover I05 has
journaled therein a shaft H3 which carries the
Worm H4 engaging the teeth of the ring 8| as
already described.
A resilient bowed washer II6 on the shaft H3 75
4
‘2,114,853
at one end of the worm lit holds the shaft H3
in a ?xed position axially so as to hold the ring
8| and the clamp bars ll and 72 ?rmly in any
position to which they may be adjusted.‘ The end
thrust thus provided between the shaft H3 and
its bearings serves frictionally to restrain rotation
of the worm till so as to maintain its adjust
ment. The shaft H3 also carries a knob H5 out
side of the cover 5235 to permit the shaft and the
worm Mil to be rotated manually for adjusting
the angular position of the ring 3% on the rocker
76 and for thereby adjusting the position of the
clamp bars ii and 12 along the path of travel
of the pointer 36.
15
In the position in which the clamping and con
tact mechanism including the rocker '56, the ring
v8! and contact bar '52 is shown in Fig. 5, the bar
12 is in its lowest position so as to avoid engaging
the bushing 37 carried by the pointer 36, and the
.20 teeth of the ringtii engagethe threads of the worm
l M. While the apparatus is in this condition, the
shaft H8 and the worm HA may be rotated by
means of the knob H5 so as to rotate the ring Si
in its seat on the rocker it‘ and thereby to move
25 the gap which occurs between the two clamp bars
"H and l2 to a different position along the path of
be noted visually with respect to the graduations
of the scale.
The clamp frame 84 carries the pointer I22
extending from the front face of the arcuate
clamp bar 1'2. This pointer is offset to bring it
into alignment with the gap between the arcuate
clamp bars ii and 12, and it terminates near the
lower window I IQ of the scale 39 through which it
may be viewed for reading its position with re
spect to the scale. The portion of the pointer 410
E22 which is visible through the window of the
scale is aligned with (i) the center of rotation
of the coil ill and pointer 36 of the galvanometer
and (2) the gap between the two arcuate clamp
bars 1! and ‘I2. Therefore, the pointer I22 indi- -:
cates that position of the scale at which the
pointer i335 will avoid being caught by either of
the two arcuate clamp bars ‘H and 12. When
the pointer 36 occupies a position to the right,
as viewed in Figs. 1 and 2, of the position indi
cated by the pointer i222, the pointer 36 will en
counter the arcuate clamp bar 72 so as to cause
an operation of the contacts associated with that
clamp bar each time that the clamp bars are
raised by the motor 55 acting through the crank' 15
57, rocker ‘it etc. Similarly, when the pointer
occupies a position to the left of the position
indicated by the pointer I22 it will be caught by
travel of the bushing 3?. Fig. 9 illustrates the
clamping and contacting mechanism in a slightly
different operated position. In Fig. 9 the clamp
bar ll has been raised by the motor 55 to the
position in which it just initially touches the bush
ing 31 carried by the pointer 38. At this position
of the rocker l8 and ring 8!, the teeth of the ring
3| have moved down and away from the teeth of
its contacts 74.
'30
The pointers 36 and I22 must be so arranged
as to avoid striking or interfering with each
other. This will be discussed presently.
The pointer 36 of the galvanometer is capable
35 the worm Ht so as to clear the same. In this
connection it is to be observed that the axis of the
of swinging through a limited angle of approxi~~ '
mately 40°. For this reason, the graduated por
pins Ti and it about which the rocker l6 tilts is
forward of the worm H4, so that, as the clamp
bars H and 12 are raised, the rear portion of the
ring 8i drops to carry its teeth out of engage~
ment and clear of the teeth of the worm I M. It
is desirable that the teeth of the ring 8| should
entirely clear those of the worm i 54 before either
clamp bar touches the bushing 3'1 carried by the
45 pointer 36 so as to prevent the clamp bars from
being rotated manually when the apparatus is in
such a condition that the needle 36 might be
carried along with the clamp bars. In any event,
these teeth should clear before the bushing 31
so
has been pressed against the stationary bar 13,
since then any motion of the clamp bars would
tend to roll the bushing'id between the clamp
bar ‘H for example and the stationary bar 753, and
.55
rotate the needle
on the wire 35.
The cover H35 also carries the scale 39, which
may be constructed of transparent cellulose ma
terial. The scale 39 includes a curved strip of
transparent material having a series of ruled lines
and numerical indexes 52E printed thereon to
60 provide the graduations and characters with re
spect to which the positions of the pointers 3t
and I22 are to be read.
scribed presently.)
(Pointer !22 will be de
Preferably the characters
I 2! are printed on the inside or back surface
65 and are adapted to be viewed through the trans~
parent material of the scale. The printed strip
is then coated on its back or inside surface with
an opaque material having a color contrasting
with that of the printed characters. The coating
70 is omitted immediately above and below the grad
uations £21 so as to leave windows H9 and i228.
he pointer
has its flat or blade portion 38
directly behind the upper window I20 through
75
which it may be viewed so that its position may
the clamp bar ‘H so as to cause an operation of
tion 526 and the windows l H] and I20 of the scale
39 are limited to the central portion thereof.
These graduations and windows extend along the
entire path or angular sweep of the pointer 36.
Each of the arcuate clamp bars ‘H and 12 is
su?iciently long that it alone can cover the com
plete range of movement of the pointer 36. Thus,
the ring 8! may be rotated in a clockwise direc
tion as viewed in Figure 4 so as to bring the 45
pointer in just beyond the extreme left de?ect
able position of the pointer 36. With the clamp
bars in this condition, the pointer 36 will be
caught by the clamp bar '52 each time that it is
raised by the motor 55 regardless of the position 50
that the pointer 35 may occupy along its entire
path of travel. Similarly, the clamping and con
tacting mechanism may be adjusted by rotating
the ring 85 to bring the pointer I22 just beyond
the extreme right de?ectable position of the 55
pointer 36 so that the pointer 36 will be caught
by the clamp bar ll regardless of the position
which the pointer may occupy. Obviously, the
mechanism may be adjusted to bring the pointer
I22 to any part of the graduated portion [2| of 60
the scale 39. With the pointer I22 set at some
position along the graduated scale l2! interme
diate the limits of the travel of the pointer 36,
the bushing 38 of the pointer 36 will engage either
the clamp bar ill or the clamp bar 72 depending 65
upon whether the pointer 36 lies to the left or to
the right of the pointer H2 at the time that the
motor 55 raises the clamp bars.
The cover £65 is made su?iciently wide to per
mit this full scale adjustment of the clamping 70
bars, that is, to permit the pointer Hi2 and the
gap between the clamping bars to be set at any
position along the graduated scale. Thus, for
example, when the pointer 22 is set at the left
end of the graduated portion it’! of the scale,
2,114,853
5
and the clamp bar ‘II lies entirely to the left of
which have a duration less than the period of
the left end thereof. The cover I05 extends be
yond the graduated portion I2I of the scale to
the periodic motion of the clamping mechanism.
The instrument controls the operation of the
contacts onlyv in accordance with the position
which the pointer occupies at the instant that it 5
is caught by the clamping jaws. Thus, for exam
ple, if the clamp bars are in the clamping posi
tion, the current in the coil Il may change sud
enclose the clamp bars in this position.
The pointer I22 and the blade or tip 38 of the
pointer 36 must be so limited in size as to prevent
them from interfering with each other. When
these two pointers occupy the same position with
respect to the graduated scale H8, that is, when
10 the pointer I22 is directly below the pointer 36,
the bushing 38 of the pointer 36 is directly aligned
with the gap between the two arcuate clamp bars
‘II and ‘I2. Therefore, when the clamp bars are
raised by the motor 55, the pointer 36 will slip
15' into this gap so as to‘ escape both clamp bars
and it will not be lifted thereby. However, the
pointer I22 which is carried by the clamp bar ‘I2
will rise therewith. Inasmuch as the clamp bar
‘I2 does not encounter the pointer 36, that clamp
20 bar will rise to approximately the position in
which it touches the bar ‘I3 and the pointer I22
will be carried to a higher position than it would
have been carried had the clamp bar ‘I2 caught
the pointer 36. Therefore, the pointer 36 and its
.tip 38 when in its normal unclamped position
must entirely clear the pointer I22 when the
latter is raised to its uppermost position by the
motor 55.
In the construction shown in the drawings
30. wherein the stationary bar ‘I3 is directly above
the moving bars ‘II and ‘I2, the difference in the
distance which the clamp bar ‘II, for example,
rises when it encounters the bushing 31 on the
pointer 36 and when it does not, can be no greater
‘5 than the thickness of the bushing 31. That is,
the motion of the clamp bar 'II with respect to the
ring 8| on which it is mounted and also with
respect to the contacts on which it operates, is
no greater than the thickness of the bushing 31.
40 Therefore, in the construction shown in the draw
ings, wherein the clamp bar operates the contacts
directly, the spacing between the contacts 92 and
95, for example, must be less than the thickness
of the bushing 31. Alternatively, the lower bars
‘ ‘II and 12 may be offset with respect to the upper
bar ‘I3 so that when the bars do not engage the
pointer, the rising bar is free to move past the
stationary bar and rise considerably above it.
This arrangement permits the motion executed
by the clamp bar in operating the contacts to
exceed considerably the thickness of the pointer
at the position in which it is clamped (for ex
ample at the bushing 31).
However, offsetting
the bars in this manner imposes a bending mo
ment upon the pointer which can be avoided only
by employing an extra bar. Thus, the lower
clamp bar may be arranged to rise between a pair
of parallel stationary bars. However the clamp
ing surfaces of the two parallel bars must be
60 ?nished with a high degree of precision in order
to insure that the pointer engages them simul
taneously. Therefore, where a motion equal to
the thickness of a bushing (such as the bushing
31) which can be carried by the pointer is suf?
cient, it is preferred to have the two clamping
bars aligned with each other as shown in the
drawings.
The relay of the present invention is not con
tinuously responsive, in that it is not immedi
70 ately responsive at all times to a change of cur
rent in its coil IT. This results from the fact
that the position of the pointer is tested only
intermittently by the clamping and contacting
mechanism. It is incapable of responding re
75 liably to transient eiTec'tsv or other conditions
denly by a considerable amount but the coil and
pointer can not rotate in response thereto because 10
the pointer 36 will be held mechanically by the
clamp bars. When the pointer subsequently is
released, it will seek the position corresponding
to the new value of current in the coil and when
the clamping jaws subsequently are brought to
15
gether again the relay will respond to the new
value of current in the coil. However, if the
current in the coil should return to its previous
value, and the coil and pointer should respond
thereto before the clamping jaws again grip the
pointer, the relay never will have responded to
that particular current condition because the
condition will not have persisted for a long
enough period of time. In order to make the
present instrument as rapid as possible in oper
25
ation, it is desirable, under certain circumstances,
to test the position of the pointer as frequently
as possible. In order to permit the instrument
accurately to indicate the value of current in its
coil, the period during which the pointer is left 30
unclamped should exceed somewhat the time re
quired by the pointer to move to a new position
and come to rest. This time is approximately 1/1
of the period of vibration of the instrument. It
is further desirable to operate the clamping 35
mechanism as rapidly as possible so as to con- _
sume as little time as possible for the clamping
or testing operation. However, the clamping bars
should rise slowly enough to engage the pointer
36 gently so as to avoid imposing excessive stress 40
on the galvanometer movement and also to avoid
disturbing the position of the pointer by striking
it sharply. Furthermore, the speed with which
the clamping mechanism may be brought into a
clamping- attitude may be limited by the power 45
capacity of the motor 55. Accordingly, the cam
65 is arranged to lift the clamping bars with an
even and gentle motion and then to drop them
rather rapidly to their lowermost position where
they are held stationary for a period of time 50
which is at least as long as the time required for
the pointer 35 to assume a new position and to
come to rest therein. However, in many appli
cations, such as temperature control applications,
the rate at which the condition to be controlled 55
is capable of changing will be so slow that the
frequency of operation of the clamping mecha—
nism may be much less than the maximum of
which the instrument is capable.
A plate I25 fastened to bosses I26 and I2‘I of 60
the cover I55 serves to close the forward portion
thereof. The plate I25 serves to protect the con
tacts and the pointers from accidental damage
and also aids in excluding dirt from the interior
of the galvanometer, the die casting I0 being
open at the position at which the pointer 36
emerges therefrom. The entire relay assembly
thus far described may be mounted on an en
closing casting I38, shown in Fig. l, which is
adapted for mounting on a vertical panel. The 70
relay is mounted on the casting I30 by means of
screws entering tapped holes in bosses I32 of the
cover I05 (see Fig. 4). Electrical connections
are made to the winding 60 of the motor 55 and
to the terminal plates (such as 93 and 96 in 75
2,114,853
6.
Fig. 9) of the contacts ‘5!! and ‘i5 may be carried
out of the cavity within the casting H15 where
the contacts are located through openings H33
at the extreme sides and rear of the cover its,
4 left uncovered by the plate I25.
Although the contacts ‘M and '55 are shown and
described as being of the normally open type,
normally closed contacts or other more complex
_, contact arrangements may be provided instead.
10" And while the relay of the present invention is
shown and described as having two clamp bars,
any number of clamp bars may be employed
having equal or unequal lengths of arcs and
_with or without gaps between them. Where no
15 gap is provided'between two clamp bars, it is
possible that the two adjacent clamp bars may
be operated simultaneously.
It is to be observed that the clamp bars ‘H
and 12 rise with a gradual motion and that the
cam 65 may be so arranged that the clamp bars
also drop with a gradual motion. Under such
conditions the time during which the contacts
be apparent that the clamp bars could align’
themselves with an are about the center of the
coil for only one adjusted position of the clamp
bars if the clamp bars rotated about any axis
other than substantially the axis of the coil.
The fact that the rocker 16 carries the ro
tatable ring 8i rather than being rotatable itself
also gives rise to certain advantages. Thus, the
cam 55 and bell crank 5'! are prevented from
exerting any rotative eiTort upon the clamp bars 10
‘H and 12 such as would tend to move the clamp
bars to a new position along the scale H8. It
also keeps the axis about which the clamp bars»
tilt ?xed with respect to the path of travel of
the bushing 38 and the limited angle of motion 15~
of the pointer 36. Therefore, the axis about
which the clamp bars rock can be given the most
advantageous orientation with respect to the
pointer 36 at every rotated position of the clamp
bars.
In the device shown and described in the
present application, the axis about which the
controlled by a clamp bar are closed or otherwise
clamp bars rock or tilt is given that orientation
which produces the greatest rise of the clamp bars
in an operated condition will depend upon the
in the region in which the pointer moves for a
25 motion which the clamping mechanism executes
on the upstroke, after the contacts operate, and
therefore upon the slack motion or motion which
it executes before the contacts operate, the total
motion as determined by the cam 65 being ?xed.
It is desirable under certain conditions that the
manner of operating the contacts should depend
in part upon the position of the pointer along
the clamp bar. By cutting the top of the clamp
,bar ‘H, for example, o? at an angle, or by pivot
35 ing the clamp bar at an angle as by tilting the
pin 37, the clamp bar will be made to hold one
portion of its clamping surface higher than an
other. If the pointer is caught by this high por
tion, the clamp bar will encounter the pointer
given angle of tilt. With this arrangement, the 25'
ring 3i which carries the clamp bars can be ro
tated through any angle, even 360°, without di
minishing the motion which the clamp bars exe
cute in the region occupied by the pointer. This
arrangement further permits the use of a simple 80
mechanism for automatically disengaging the
drive for adjusting the position of the clamp bars
during the time that the clamp bars are raised
to bring them into a clamping attitude with re
spect to the pointer 36.
35
The fact that the gear teeth on the ring 8|
face upward permits them to disengage and swing
clear of the teeth of the worm Hi When the clamp
ing mechanism is tilted; and it permits these
40' sooner and disengage it later so as to hold its
gear teeth to serve as a stop for the tilting and 40
contacts closed for a longer period of time than
if the pointer is caught by a low portion of the
bar. Thus, the two bars ‘H and 72 may be ar
ranged to be low near the gap between them so
that the length of time in which the contacts
are closed increases with the deviation of the
clamping mechanism when that mechanism drops
to its lowermost position. By employing the worm
l4, through its engagement with the teeth of the
ring Bi, as the stop for the rocker 16 and the
apparatus carried thereon, these teeth are brought 4-5
position of the pointer 36 from the position of
the pointer 522. Thus, the apparatus which the
, relay of the present controls may be arranged to
50* effect a control function which varies in magni
?rmly into engagement so as to eliminate any
back lash or play between the teeth of the wormv
Md and those of the ring 8!.
The apparatus of the present invention may
be employed, for example, in a temperature regu
tude with the length of time that the contacts
lating system, the temperature of the apparatus
are closed so as to provide a graduated response
to be controlled may be measured by a resistance
thermometer, thermocouple or other known elec
trical device, the galvanometer coil H of the pres
ent invention being employed therewith as the
indicator or current measuring device. The
which increases with the magnitude of the total
,correction required.
Alternatively, the bars ‘H
‘and '12 may be notched or stepped to provide a
graduated response of the type indicated.
In the relay of the present invention a consid
erable advantage accrues from the fact that the
clamp bars ‘H and ‘i2 are rotatable about the
same axis as the coil H and its pointer 36. This
permits the clamp bars to be so arranged as
always to engage the pointer at substantially the
same portion thereof so that the comparatively
heavy bushing 38 need not extend along more
than a very small part of the total length of the
pointer 36. It also permits the upper or stationary
bar 73 and lower bars ‘ll and 12 to be perfectly
aligned in every position. If the upper and lower
bars should be arranged so that they pass each
other in the manner already described, this
alignment permits the upper and lower bars to
pass each other with only a small space between
them so as to limit the bending moment imposed
_upon the comparatively frail pointer of the gal
75 vanometer when clamping the same. It should
pointer I22 may be adjusted to that position of
the scale which corresponds to the temperature
at which it is desired to maintain the controlled
apparatus. The contacts of the clamp bars 1|
and 12 may be arranged respectively to heat and
cool that apparatus, or the cooling function for
example may be omitted in which case only the
contacts 74 of the clamp bar ‘H will control a
load. As long as the pointer 36 occupies the same
scale position as the pointer I22, neither of the
clamp bars I22 will operate its contacts. When
the pointer 36 moves slightly to the left of the
position indicated by the pointer {22, it will be
caught by the clamp bar ‘H and thereby will cause
the heating apparatus to be set into operation
each time that the clamp bars are raised by the
motor 55. This will increase the temperature of‘
the device being controlled so that the electri
cal temperature measuring apparatus connected
2,114,868
to the coil I1 eventually will cause the pointer
36 to de?ect towards the right. However, the
pointer 36 will continue to cause the contacts
which are associated with the arcuate clamp bar
ll periodically to be operated until the tempera
ture rises to such value that the pointer 36 moves
to the position indicated by the pointer I22 or
to the right thereof.
It will be apparent to those skilled in the art
10 that the speci?c embodiment of the invention
herein shown and described is illustrative only,
and that the invention is capable of numerous
modi?cations and variations. Therefore, the in~
vention should not be limited except by thev scope
16 of the appended claims.
We claim:
1. In combination in a device of the class
described, a galvanometer having a pointer which
is rotatable about an axis, a pair of clamp bars
20 adapted to clamp said pointer and means for re
peatedly moving at least one of said bars to bring
said bars into a clamping attitude with respect
to said pointer and to withdraw them therefrom,
electric contact mechanism adapted to be oper
25 ated by'mechanical force, at least one of said
clamp bars being mechanically coupled to said
contact mechanism so that the force with which
said bars clamp said pointer serves to operate
said switch.
30
2. In combination in a device of the class de
scribed, a galvanometer having a pointer which
is rotatable about an axis, a pair of clamp bars
adapted to clamp said pointer in rotated posi
tion, said clamp bars being arcuate and having
35 the centers of their arcs substantially at said axis
of said pointer and means for repeatedly moving
at least one of said bars to bring said bars into
a clamping attitude with respect to said pointer
and to withdraw them therefrom, at least one of
40 said bars being rotatable substantially about said
axis of the galvanometer and extending less than
360° about said axis.
3. In combination in a device of the class de
scribed, a galvanometer having a pointer which is
45 rotatable about an axis, said pointer consisting
of a thin-wall metal tube,'a pair of clamp bars
adapted to clamp said pointer, said clamp bars
being arcuate and having the centers of their
arcs substantially at said axis of the galvanom
50 eter, means for repeatedly moving at least one
of said bars to bring said bars into a clamping
attitude with respect to said pointer and to with
draw them therefrom, at least one of said bars
being rotatable substantially about said axis of
55 the galvanometer and extending less than 360°
about said axis, and a bushing on said pointer for
supporting the pressure exerted on said pointer
by the clamping action of said clamp bars, said
bushing being carried by said pointer on the por
60 tion thereof which encounters said clamp bars’
4. In combination in a device of the class de
scribed, a galvanometer having a pointer which
is rotatable about an axis, a graduated scale with
respect to which said pointer indicates its own
deflected position, a pair of clamp bars having
clamping surfaces adapted to clamp said pointer,
means for moving at least one of said bars to bring
said clamp bars into a clamping attitude with re
spect to said pointer and to withdraw them there'
> from, at least one of said bars being rotatable
substantially about the axis of said pointer and
having its clamping surface limited in the direc
tion about said axis, a second pointer rotatable
substantially about said axis with the rotatable
clamp bar, said second pointer indicating on said
7
graduated scale the position of the margin of the
limited clamping portion of said rotatable clamp
bar, said means including an electric contact
mechanism adapted to be operated by mechanical
force and so coupled to one of said clamp bars
that the force with which said bars clamp said
pointer serves to operate said switch.
5. In combination in a device of the class de
scribed, a galvanometer having a movable pointer,
a pair of clamp bars having clamping surfaces 10
adapted to clamp said pointer, means for re
peatedly moving at least one of said bars to
bring said clamp bars into a clamping attitude
with respect to said pointer and to withdraw them
therefrom, at least one of said clamp bars having 15
its clamping surface so limited in extent as to
cover less than the full path of motion of said
pointer whereby said clamp bars are adapted to
clamp said pointer only when said pointer occu
pies certain portions of its path of motion, elec 20'
tric contact mechanism adapted to be operated
by mechanical force, at least one of said clamp
bars being mechanically coupled to said contact
mechanism so that the force with which said bars
clamp said pointer serves to operate said switch. 25
6. In combination in a device of the class de
scribed, a galvanometer having a pointer which
is rotatable about an axis through a limited angle,
a pair of clamp bars for clamping said pointer,
and means for moving at least one of said clamp 30
bars so as to bring said clamp bars into a clamp
ing attitude, said means comprising a support for
said one clamp bar, said support being tiltable
about a fixed axis which is substantially perpen
dicular to said axis of the galvanometer and 35
which is substantially perpendicular to the medi
an position of said pointer in said limited angle
of rotation.
7. In combination in a device of the class de
scribed, a galvanometer having a coil carried on
taut suspensions and having a pointer carried
on said coil, said coil and pointer being rotatable
through a limited angle, said pointer extending
from said coil and having a clamp engaging por
tion removed from the axis of the taut wire sus 45
pensions in a radial direction and removed in a
direction along said axis of the taut wire suspen
sions from the center of said coil, a pair of clamp
bars for clamping said pointer, one of said clamp
bars being movable about a tilting axis to bring 50
said clamp bars into a clamping attitude, said
tilting axis being substantially perpendicular to
said axis of the taut wire suspensions and sub
stantially perpendicular to a line radiating from
the axis of the taut wire suspensions and inter 55
secting the median position in the range of posi
tions of the clamp engaging portion of said point
er, said range of positions of said clamp engag
ing portion being determined by said limited
angle of rotation of said pointer, said tilting axis 60
being located with reference to the direction of
said axis of the taut suspension wires between
said clamp engaging portion of said pointer and
the center of said coil, said tilting axis being lo
cated with respect to the direction of said line (i5
radiating from the axis of the taut wire suspen
sions and intersecting said median position of
said clamp engaging portion of said pointer, to
that side of said clamp engaging portion of the
pointer on which lies said axis of the taut wire
suspensions.
8. In combination in a device of the class de
scribed, a galvanometer having a pointer which
is rotatable about an axis through a limited
angle, a pair of clamp bars adapted to clamp
81'
2,114,863
said pointer, at least one of said clamp bars be
ing movable about a ?xed tilting‘ axis to bring
said clamp bars into a clamping attitude, said‘
?xed tilting axis being‘ substantially‘ perpendicu
' lar to the axis of rotation of the pointer and sub
stantially perpendicular to the median position
of said pointer in the limited angle of rotation
thereof, at least one of said clamp bars being
rotatable approximately about the axis of rota
10' tion of said pointer and extending about said
axis less than 360°.
9. In combination in a device of the class de
scribed, a galvanometer comprising a substan
tially closed housing, a coil therein and a pointer
15' carried by said coil, said coil and pointer being
rotatable about a coil axis through a limited
angle, a pair of clamp bars adapted to clamp said
pointer, means for moving at least one of said
clamp bars so as to‘ bring said‘ clamp bars into
20’ a clamping attitude with respect to said. pointer,
said means comprising a supporting structure for
said one clamp bar, said supporting structure
comprising a rocker supported on said housing
and tiltable thereon about an: axis which is sub
25 stantially perpendicular to the coil axis and. sub
stantially perpendicular to a median position of
said pointer with respect to said limited angle,
said supporting structure comprising also am'em
ber rotatable on said rocker about an axis. which
is substantially coincident with said coil axis for
one tilted position of said" rocker, said one clamp
bar extending about said axis less than 360°.
(2) said clamp bar when in said clamping atti
tude is adapted to engage and clamp said pointer
or to avoid clamping the same in accordance with
the rotated position of said pointer relative to
the rotated position of said one clamp bar; and
(3) said clamp bar is adapted to rotate to change
its rotated position, so as to change the respective
rotated positions at which said pointer is adapted
toescape and engage said clamp bar.
12. In. combination in a device of the class de
scribed, a galvanometer comprising a substan
tially closed‘ housing, a coil therein, and a pointer
carried by said coil, said pointer and coil being
rotatable together about a coil axis through a
limited angle, a pair of clamp‘ bars adapted to
clamp said pointer, means for moving at least one
of said clamp bars so as to bring said clamp bars
into a clamping attitude with respect to said‘
pointer and to withdraw them therefrom, said
means comprising a supporting structure for‘said 20-1
one clamp bar, said supporting structure com
prising a rocker supported on said housing and
tiltable thereon about a rocker axis, said rocker
axis being ?xed with respect to said housing, said
supporting structure comprising also a member 251
carried on said rocker and rotatable about a third
axis, said third axis being ?xed with respect to
said rocker and lying approximately in the di
rection and position of said coil axis of the galva
nometer, said one clamp bar being rotatable with 30?
said rotatable member and extending about said’
coil and third axes less than 360", a driving mem
scribed, a galvanometer having a pointer which
is movable along a path of travel thereof, a pair
ber for said rotatable member adapted to make
driving engagement with said rotatable member"
at a position off said third axis about which said? 35
of clamp bars adapted to clamp said: pointer,
rotatable member rotates on said rocker and off
?rst means for moving at least one of said clamp
bars to bring said clamp bars into a clamping
attitude with respect to said pointer and. to‘ with
40: draw them therefrom, at least one‘ of said clamp
bars being movable along said path of travel of
said rocker axis about which said rocker tilts,
said rocker being adapted to tilt about said rocker
axis to accomplish the following in a single mo
10. In combination in. a device of the class de
the pointer and being adapted‘ to extend less than
the full length of said path of travel in at least
one position of said clamp barv along saidv path
‘' of travel, and second meansfor driving said last
mentioned one clamp bar along‘ saidv path of
travel, said second means‘ being operable only
when said‘ ?rst means-has withdrawn said clamp
bars from a clamping attitude with.- respect to
50 said pointer,
11. In combination in a device of the. class
described‘, a galvanometer housing, a- coil sup
ported therein and‘ rotatable therein about a coil
axis through‘ a limited angle,. a pointer‘ carried
on said coil andv rotatable therewith, said pointer
extending out of said housing, a pair of clamp
bars adapted‘ to clamp, said pointer, means for
supporting one. of said‘ clamp: bars, said means
(EU
comprising a ring shaped- rocker encircling said‘
housing and‘ supported thereon, said rocker be‘
ing tiltable on said housing about a: rockerv axis
which is ?xed with respect to said. housing, said‘
means comprising. also a ring shapedl rotatable
member encircling said. housing. carried.- on said
(35 rocker and rotatableon' said rocker‘ about" a third:
axis which is ?xed with. respect tov said: rocker,
said one clamp bar‘ being carried by said’ rotat
able member and being rotatable. therewith, said‘
one clamp bar extending less than360° about said
coil axis and about said‘: third. axis, and- being
adapted to engage said pointer at a point oiT
said coil axis, off said. rocker‘ axis‘ and. oil said
third axis, whereby ('1'). said: one clamp bar is
adapted to tilt.‘ with said rocker into and5 out of
a. clamping attitude with respect to said pointer;
tion in one direction of rotation about said rocker
axis: (1) move said one clamp bar to bring said’
clamp bars into a clamping attitude with respect
to said pointer; and (2) withdraw said rotatable
member from driving engagement with said driv
ing member.
13. In combination in a device of- the class de~
scribed, a galvanometer comprising a substan
tially closed housing, av coil therein and a- pointer
carried on- said coil, said coil and pointer being
rotatable together about a coil axis through a 50:
limited angle, the median position of said pointer
in said angle being forward of said housing, a
pair of clamp bars lying above and below the
path of said pointer for clamping said pointer,
means for moving the lower one of said- clamp
bars so as to‘ bring said clamp bars into a clamp‘
ing- attitude with respect to said pointer, said
means comprising a supporting structure for said
lower clamp bar, said supporting structure com—
prising a rocker encircling said housing and hav 60
ing a circular seat encircling said housing, said
rocker being supported on said housing and tilt
able thereon about a rocker axis which is ?xed.
with respect to. said housing, said rocker axis ly-'
ing substantially perpendicular to said coil axis
and substantially perpendicular to said median
position of said pointer in said limited angle, said
supporting structure comprising also a rotatable
member encircling said housing, said‘ rotatable
member being carried on said rocker and beingv 70
rotatable on said seat about a third axis which
is ?xed with respect to said rocker and which
is substantially coincident with said coil axis for
one tilted position of said rocker, said lower clamp
bar extending about said coil axis and’ about 75
2,114,858
said third axis less than-360°, said rotatable mem
ber having teeth arranged in a circular pattern
, thereon about said third ‘axis, a worm engaging
said teeth at the rear of said circular pattern,
said worm being rotatable about an axis which is
?xed with respect to said housing for rotating
said rotatable member on said rocker, said axis
of said worm lying approximately parallel to said
rocker axis, said rocker axis lying forward of said
axis of said worm and aft of said lower clamp
bar, said teeth of said rotatable member being
adapted to disengage said worm by dropping away
therefrom, said rotatable member being adapted
to tilt with said rocker about said rocker axis
15 to accomplish the following in a single motion
in one direction of rotation about said rocker axis:
(1) raise said lower clamp bar into a clamping
attitude with respect to said pointer; and (2)
drop said teeth of said rotatable member out
20 of engagement with said worm.
14. In combination in a device of the class de
scribed, a galvanometer comprising a substan
tially closed housing, a coil therein, and a pointer
carried by said coil, said pointer and coil being
rotatable together about a coil axis through a
limited angle, a pair of clamp bars for clamping
said pointer, means for moving at least one of
said clamp bars so as to bring said clamp bars
into a clamping attitude with respect to said
30 pointer and to withdraw them therefrom, said
means comprising, a supporting structine for
said one clamp bar, said supporting structure
comprising a rocker supported on said housing,
and tiltable thereon about a rocker axis, said
35 rocker axis being ?xed with respect to said hous
ing, said supporting structure comprising also a
9
lower clamp bar, said supporting structure com
prising a rocker encircling said housing and hav
ing a circular seat encircling said housing, said
rocker being supported on said housing and tilt
able thereon about a rocker axis which is ?xed 5
with respect to said housing, said rocker axis
lying substantially perpendicular to said coil axis
and substantially perpendicular to said median
position of said pointer in said limited angle,
said supporting structure comprising also a ro 10
tatable member encircling said housing, said ro
tatable member being carried on said rocker and
being rotatable on said seat about a third axis
which is ?xed with respect to said rocker and
which is substantially coincident with said coil 15
axis for one tilted position of said rocker, said
lower clamp extending about said coil axis and
about said third axis less than 360°, said rotat~
able member having teeth arranged in a circular
pattern thereon about said third axis, a worm 20
engaging said teeth at the rear of said circular
pattern, said worm being rotatable about an axis
which is ?xed with respect to said housing for
rotating said rotatable member on said rocker,
said axis of said Worm lying approximately par~ 25
allel to said rocker axis, said rocker axis lying
forward of said axis of said worm and aft of
said lower clamp bar, said teeth of said rotatable
member being adapted to disengage said worm by
dropping away therefrom, said rotatable member 30
being adapted to tilt with said rocker about
said rocker axis to accomplish the following in a
single motion in one direction of rotation about
said rocker axis: (1) raise said lower clamp bar
into a clamping attitude with respect to said 35
pointer; and (2) drop said teeth of said rotatable
member carried on said rocker and rotatable
member out of engagement with said worm, a
about a third axis, said third axis being fixed with
respect to said rocker and lying approximately
40 in the direction and position of said coil axis,
graduated scale cooperating with said pointer for
said one clamp bar being rotatable with said r0
tatable member and extending about said coil and
third axes less than 360°, a driving member for
said rotatable member adapted to make driving
engagement with said rotatable member at a
position off said third axis about which said ro
tatable member rotates on said rocker and off
indicating on said scale the rotated position of
said pointer about said coil axis, a second pointer 40
rotatable with said rotatable member for indi
cating on said scale the rotated position of said
one clamp bar about said third axis, said lower
clamp bar being hinged on said rotatable mem
ber about an axis which is approximately per 45
pendicular to said third axis, and contacts car
ried by said rotatable member and adapted to be
said rocker axis about which said rocker tilts,
said rocker being adapted to tilt about said rocker
operated by said lower clamp bar when said
clamp bars engage and clamp said pointer.
50 axis to accomplish the following in a single mo
tion in one direction of rotation about said rocker
having a cylindrical portion, a galvanometer
axis: (1) move said one clamp bar to bring said
clamp bars into a clamping attitude with re
spect to said pointer; and (2) withdraw said ro
55 tatable member from driving engagement with
said driving member, a graduated scale coop
erating with said pointer for indicating on said
scale the rotated position of said pointer about
said coil axis, a second pointer rotatable with
60 said rotatable member for indicating on said
scale the rotated position of said one clamp bar
about said third axis.
15. In combination in a device of the class de
scribed, a galvanometer comprising a substantial
ly closed housing, a coil therein and a pointer
carried on said coil, said coil and pointer being
rotatable together about a coil axis through a
limited angle, the median position of said pointer
in said angle being forward of said housing, a
70 pair of clamp bars lying above and below the
path of said pointer for clamping said pointer,
means for moving the lower one of said clamp
bars so as to bring said clamp bars into a clamp
ing attitude with respect to said pointer, said
75 means comprising a supporting structure for said
16. In a device of the class described, a frame 50
housed in said cylindrical portion of said frame,
a rocker carried by said cylindrical portion, a
ring positioned on said rocker and carried there
by, said ring encircling said cylindrical portion, 55
a pair of clamp bars pivotally supported on said
ring, a stationary clamp bar carried on said
frame and positioned near each of said pivoted
clamp bars, means carried on said frame for im
parting a rocking movement to said rocker and 60
for thereby rocking said pivoted clamp bars to
wards and away from said stationary clamp bar,
a pointer actuated by said galvanometer and
adapted to swing between said stationary clamp
bar and said pivoted clamp bars, electrical con 65
tacts carried by said ring and adapted to be oper
ated by said pivoted clamp bars, said ring, con
tact and pivoted clamp bars being rotatable to
gether on said rocker, and a housing enclosing
the foregoing apparatus.
70
17. In combination in a device of the class de
scribed, a galvanometer having a pointer which
is rotatable about an axis, a pair of clamp bars
adapted to clamp said pointer and means for
moving one of said bars so as to bring said bars
75
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into a clamping attitude with respect to said
pointer, said means including a power actuator
and a driving connection between said power
actuator and said one bar, and electric contact
mechanism included in said driving connection
adapted to be operated by the pressure with
which said bars clamp said pointer.
18. The combination of the immediately pre
ceding claim wherein said means includes a tilt
10 able member carrying said contact mechanism,
wherein said contact mechanism includes a mov
able part for urging said one clamp bar into its
clamping attitude, and wherein said power actu
ator tilts said tiltable member to move said con
15 tact mechanism against said bar, whereby when
the pointer obstructs the motion of said bar,
the power actuator operates said switch mecha
nism. '
19. In combination in a device of the class
described, a galvanometer having a pointer ro
tatable about an axis, a pair of clamp bars
adapted to clamp said pointer, means for moving
one of said bars toward said pointer to bring
said bars into a clamping attitude and electric
25 contacts operated by said means when said bars
clamp said pointer, said means including a tilt
able member and a power actuator for tilting
it, said contacts comprising a pair of cantilever
contact blades supported on said tiltable member,
30 one of said blades being ?exible and bearing
against said one contact bar to urge it toward
clamping position as said tiltable member tilts
so that when the pointer obstructs the motion of
said bar said one blade must ?ex as said tilt
V35 able member tilts, whereby to operate said con
tacts.
20. In combination in a device of the class
described, a galvanometer having a pointer which
is rotatable about an axis, said pointer consist
40 ing of a thin-wall tube, a pair of clamp bars
adapted to clamp said pointer, means for mov
ing at least one of said bars to bring said} bars
into a clamping attitude with respect to said
pointer, and a bushing on said pointer for sup
45 porting the pressure exerted on said pointer by
the clamping action of said clamp bars, said
bushing being carried by said pointer on the
portion thereof which encounters said clamp
bars.
21. In combination in a device of the class de
scribed, a galvanometer having a pointer which
is movable along a path of travel thereof, a pair
of clamp bars adapted to clamp said pointer,
means for moving at least one of said clamp bars
to bring said clamp bars into a clamping atti
tude with respect to said pointer and to with 10
draw them therefrom, at least one of said clamp
bars being movable along said path of travel of
the pointer and being adapted to extend less
than the full length of said path of travel in at
least one position of said clamp bar along said
path of travel, and adjusting means for driving
said last mentioned one clamp bar along said
path of travel, said last means being operable
only when said clamp bars are not in a clamping
attitude with respect to said pointer, said ad
justing means being incapable of operating said
clamp bars into or out of a clamping attitude
with respect to said pointer.
22. In combination in a device of the class de
scribed, a galvanometer having a pointer rotat
able about an axis, means for detecting the posi
tion of said pointer, said means including a
clamp bar adapted to be moved toward said
pointer to bring it into a clamping attitude with ,
respect thereto, a tiltable member having a pro
jection thereon for supporting a contact struc
ture, a sheet of insulating material folded over
said projection to cover the extended end and
two opposed faces of said projection, the ends of
said sheet extending out away from said op
posed faces of said projection, and contact
blades mounted cantilever fashion on said pro
jection on the outside of said sheet of insulat
ing material, said sheet being wider than either
said projection or said contact blades, said tilt
able member being adapted to rock said contacts
against said clamp bar to urge said bar toward
said pointer.
ARCHIE J. McMASTER.
WALTER VAN GUILDER.
110
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