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Jan. 14,1947.
J. H.-MO0RE
2,414,161
DYNAMOMETER
Filed Feb. 2, 1945
NVENTQR
ATTORNEY‘
V
Patented Jan. 14, 1947
2,414,161
UNITED STATES PATENT OFFICE
2,414,161
DYNAMOMETER
John H. Moore, Spring?eld, Pa., assignor to The
Baldwin Locomotive Works, a corporation of
Pennsylvania
Application February 2, 1945, Serial No. 575,822
2 Claims.
(Cl. 73-441)
1
2
This invention relates generally to dynamom
into terms of load or force. However, load
weighing equipment when used in a portable
eters and more particularly to weighing devices
such as crane scales whereby castings and other
manner such as for a crane scale or for other
products may be Weighed by lifting the same
uses in subject to very severe and rough treat
with a usual crane in machine shops, foundries, 5 mentas a normal part of its use. Such use
shipyards and the like, although the invention
may arise from suddenly lifting a weight or of
is also applicable in other ?elds where load forces
transmitting a sudden force or the device may
are to be weighed or measured.
be dropped on the ?oor or thrown into a tool
It is an object of my invention to provide an
room crib upon completion of a weighing oper
improved dynamometer that is relatively simple 10 ation or otherwise “kicked around.” The ability
and economical in construction, operation and
maintenance and has a high degree of accuracy
and sensitivity combined with ruggedness, com
pactness and ease of application.
Another object is to provide an improved dyna
mometer that has the desirable qualities of the
foregoing object and in addition is readily port
able and has maximum safety in the event of
to withstand such rough treatment must how
ever, be combined with sufficiently light weight
so that the device can be easily manually lifted
into position on a crane hook or other load pro
ducing member.
As shown in Fig. 1, I have provided a tension
type load responsive dynamometer bar I pref
erably circular in cross-sectional area and con
nected through enlarged ?lleted ends 2 and 3
A further object is to provide an improved 20 with integrally formed ?anged heads 4- and 5.
dynamometer so arranged that eccentric or later
The upper head is preferably provided with a
ally swinging loads or forces will not have any
threaded boss 6 from which a connecting ele
excess load.
substantial effect upon the accuracy or interfere
with easy determination of the load;
Other objects and advantages will be more
apparent to those skilled in the art from the
following description of the accompanying draw
ing in which:
Fig. 1 is a vertical section through one form
ment such as an eye 1 extends.
The lower head ,
is provided with a plain boss 8 having a reduced
threaded portion 9 from which a connecting
element such as a hook Ill extends. This entire
structure is preferably formed as a single in
tegral member which thus provides a high de
gree of homogeneity as well as allowing a very
of my improved dynamometer, certain parts of 30 effective stress distribution in the elongated
which are shown in elevation;
strain responsive tension bar I whose length is
Fig, 2 is a perspective of Fig. 1 shown in use
several times its diameter and consequently the
on a crane hook;
middle portion of the bar is free of end. effects,
Fig. 3 is a modi?ed form of my improved
i. e. stress concentrations in the ends of the bar.
To utilize this central portion of the bar its di
Fig. 4 is a transverse section taken substan 35 ametrically opposite sides have slightly flat sur
tially in the plane indicated by the line 4—4 of
face areas such as H and I 2,‘there being four
Fig. 3;
such surfaces altogether arranged at 90° to each
Fig. 5 is a fragmentary perspective view of the
other. Mounted upon these ?at surfaces are
strain responsive element of Fig. 3 showing the 40 bonded wire type strain gages l3r—l3d whose
load supporting studs thereof formed as an in
electrical resistances varies with its strain. These
tegral part of the element;
gages are connected together as a part of a suit
Fig. 6 is a wiring diagram of the gages used
able electrical measuring circuit such as a Wheat
in Fig. 1.
stone bridge whose unbalance can be graduated
The particular embodiments of the invention 45 in terms of pounds, such circuit being shown in
disclosed herein have their various elements so
Fig. 6. Temperature compensating bonded wire
constructed and arranged that electrical im
type gages l3’ and-l3” are wrapped around and
pedance means, particularly of the bonded wire
bonded to the upper and lower circular sections
type strain gage such as disclosed in Simmons
of the tension bar.
Patent Nb. 2,292,549, may be effectively em 50
To provide not only maximum protection to
ployed to measure strain produced in a member
the dynamometer against rough usage but also
by a load or force transmitted therethrough.
insure complete safety to the operator during
The strain gage of the above type undergoes a
operation in case of failure of the tension bar,
change of electrical resistance in response to
a casing generally indicated at l5 of relatively
strain and such resistance change is translated 55 heavy construction has a ?ange overlying the
dynamometer;
2,414,161
3
4
upper ?anged head 4 and is preferably held
thereon by threads 6. This casing is divided
annular ring 30 provided, as shown in Figs. 3
and 5, at its upper and lower diametrically oppo- ‘
site points with a pair of axially extending studs
for purposes of assembly into several sections
or bearing bosses 3I whose threaded ends 32
such as It‘, I1 and I8, the section I‘! being
threaded into member I6 and section l8 into I‘! 5 are of somewhat smaller diameter than the bear
ing bosses. The bearings 31 and 32 are formed
thereby permitting the casing I5 to be separated
integrally with the ring either by forging the ring
at its center to provide maximum access to the
and bosses from one piece or by machining them
gages I3 during wiring or inspection thereof.
[from a single piece. The ring and also the ten
The inner section I8 has a safety ?ange I9 under
lying head 5 and vertically spaced therefrom 10 sion bar are of any suitable material, preferably
a su?icient distance to allow elongation (strain)
steel, whose elastic properties are safely within
the desired load capacity. The ring is secured to
of bar I within the designed capacity of the dyna
mometer. Upon excess loading the head 5 will
a pair of side links 33 and 34 which are held in
either engage the safety ?ange I9 and prevent
position on bearings 3I by nuts 35. These brack
further transmission of load through the dyna 15 ets are preferably inclined outwardly'at 36 and
then upwardly to provide adequate spacing be
mometer bar I or in the event of failure of the
tension bar the safety ?anges will limit the sepa
tween their uppermost ends 31 which have
aligned bolt holes 38. An upper casing head disc
ration of the end connections. There is prefer
ably a small annular clearance between the mem
39 has a pair of slots through which the links
ber I8 and the periphery of ?ange 5 although 20 extend, the head being preferably welded thereto
although the head may be secured to a member
39’ which is secured to the links to hold them in
ber I8.
?ed spaced relation to each other. A similar set
To prevent dirt or other foreign material from
of side links 40 and M is connected to the lower
entering the interior of easing I5 and still not 25 set of bearing bosses and is held thereto by nuts
adversely affect the accuracy of the load weigh
42. A pair of bolt holes 43 is also provided.
ing device, I provide a ?exible bellows 20 whose
Strain of the annular ring 3|] in response to a
upper ?ange is held against section I8 by an
load is measured by strain gages of the bonded
annular nut 2|, while the lower end of the bel
wire type above mentioned and shown at 44 and
lows is held against the boss 8 by a nut '22 se 30 45. Each half of the ring has such gages placed
cured on threaded portion 9. The casing is thus
on both the outer and inner surfaces making a
supported at its upper endby one of the connect
total of four gages. The dynamometer may be
ing elements while the lower end of the casing
connected to a crane and held by pins (not
under certain circumstances, if desired, the ?ange ‘
could have a free sliding contact with the mem
“ is unsupported in that the bellows is ?exible both
shown) extending through ‘holes 38 and 43 or
laterally and axially to freedom of movement
between the lower end of the casing and the con
the dynamometer may be bolted to‘ any other
necting means.
By this arrangement I accom
plish both rugged protection and ?exibility in op
members to measure a force. The gages may
be connected in a measuring circuit in the same‘
manner as mentioned for the Fig. 1 modi?cation.
eration.
If desired, a casing 41 may be ?rmly secured to
In operation, the eye 1 will be bolted to any 40 the head 39 by screws, welding or other suitable
suitable member or the eye may be of sufficient
means to enclose the strain responsive ring 30,
size to permit it to be thrown over a crane hook
and this casing, like casing I5, has su?icient rig
diagrammatically indicated at 24. The hook I0,
idity either in itself or in combination with the
or any other suitable form of connecting element
remaining structure to provide protection in case
that may be used in place of the hook is attached 45 of rough usage. A horizontally split disc 48 is
to a lifting cable or rod 25 connected to what
secured to a cross piece 49 which in turn is mount
ever object is to be weighed such, for instance,
ed upon a spacing element 50 secured to the lower
as a casting, piece of machinery, etc. Upon rais
links 40 and M to hold them apart. To seal the
ing the crane hook 24 by a usual crane the dy
interior, a bellows 5| is clamped in disc 48 and
namometer bar I will be strained in tension in _
extends between the same’ and the lower end of
proportion to the load being weighed and accord
the casing to which the bellows is removably held
ingly the electrical resistance of the strain gages
by an annular nut 52.
will change in proportion to the load. These
From the foreging disclosure of the two modi
strain gages are suitably connected to leads (not
?cations, it is seen that I have provided an ex
shown) which pass through any suitable open~ ;
tremely simple, rugged and compact dynamom
ing in the casing, one of which is diagrammat
ically indicated at 26, Fig, l, and from there the
curacy and durability and is capable of portable
eter that has a high degree of sensitivity, ac
leads are connected through a ?exible lead cord
use and ease in its application. The load and
to a suitable measuring or indicating instrument
strain responsive element, whether it be the ten
well-known in the art. The operator stands on 60 sion bar I or the ring 30 with its combined ten
the ?oor and holds the small size indicating in
sion-compression action on the inner and outer
strument to read the same while the dynamom
surfaces when subjected to a load, is adapted to
eter is hoisted into the air. Any lateral swinging
weigh the load with minimum eccentric loading
of the load on hook II] will not adversely affect
effects even though the load may have some de
the load reading for the reason that'the gages 65 gree of swinging during the weighing operation.
are so arranged in all four arms of the bridge
The combination of elements in my improved de
in Fig. 6 that any eccentric loading in bar I will
vice inherently provides the ruggedness necessary
cause compression in gage I3a to cancel the
to give complete physical protection to the device
tension in gage I31), and similarly for gages I30
and yet is of sufficiently light weight to allow
and I3d. Gages I3’ and I3" complete the four 70 ready portable use.
arms of the bridge to obtain not only tempera
It will of course be understood that various
ture compensation but also increased sensitivity
changes in details of construction and arrange
due to the effect of Poisson's ratio.
_ment of parts may be made by those skilled in
In the modi?cation shown in Fig. 3 the load
the art without departing from the spirit of the
responsive dynamometer member is a continuous 76 invention as set forth in the appended claims.
2,414,161
5
I claim:
.
1. A dynamometer comprising, in combination,
a load responsive member whose strain varies
with its load, a pair of connecting elements se
cured to said member to transmit load there
through to strain the same, bonded wire type
strain gages mounted on said member whereby
6
2. A dynamometer comprising, in combination,
a load responsive member, a pair of connecting
elements secured to said member to transmit load
therethrough to strain the same, a casing enclos
ing said load responsive member and having
threaded connection therewith at one end there
of, and means removably connected to the other
end of said casing to form a part thereof and
adapted to limit the extent of separation of said
being a tension bar terminating in its opposite 10 connecting elements, said casing being of suffi
ends in enlarged integral ?anges, and a casing
cient strength so as to carry the whole load trans
having axially separable but connected sections
mitted between said elements in the event of fail
with upper and lower inwardly extending ?anges
ure of said load responsive member.
disposed in overlapping relation to the ends of
the enlarged ?anges, whereby upon separation of 15
JOHN H. MOORE.
said sections they are removable in opposite di
rections from the ends of the load member.
the strain gages measure the strain of said mem
ber as an index of the load, the load member
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