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Nov. 19, 1946.
C. E. MILLER ET AL
2,41 1,450
MATERIAL TESTING APPARATUS
Filed July 28, 1944
2828a
3|5Ia35
26
241:
Fig.1.
Inventors:
Caries E. Miller“,
Robert, J. Demar inf,
b 541,47 éfxj
yTheir Attorney.
reamed Nov. 19, 1946
~
2,411,450
UNITED ‘STATES PATENT OFFICE
2,411,450
MATERIAL TESTING APPARATUS
Charles E. Miller, Scotia, and Robert J. Demar~
tlni, Schenectady, N. Y.. asaiznors to General
Electric Company, a corporation or New York
Application July 28, 1944, Serial No. 547371
16 Claims. (Cl. "BB-F90}
This invention relates to the testing of ma
terials, more particularly to apparatus for test
Means are provided for producing a control
voltage which varies in accordance with the
ing material samples, and it (has for an object
difference in speeds
the
l retainers. This
the provision of a simple, reliable, inexpensive,
control voltage is utilized to control suitable
and improved apparatus of this character.
in the testing of many materials such as tex~ 5 electric valve apparatus to control the supply of
current to the motor which drives
testing
tile fabrics, the apparent strength of the ma
machine to e"
" speeds oi’ the two 2nem=
terial as determined by a testing machine varies
hers.
means are pro—
materially with variations in the rate at
vided for
3 reference volt=
Which load is applied to the test sample. The
‘o
5 produces
rate or" application of load to the material sample,
opal
the
in turn, depends upon the elasticity or “stretch
d the din
iness” of the material. sample. Consequently,
7
has
voltages
the
two
utilised
contr
markedly different indications of tensile strength . voltages a-..d t
are obtained from material samples having the
rate.
to the
same actual tensile strength but having di?erent
Q
elasticities. Accordingly, a further object of
this invention is the provision of means for con
trolling a testing machine in such a manner that
the rate of application of load to the test sample‘
should now he
9
had to the following spec
_ and to the
accompanying drawing of
is independent of the elasticity of the material 20 simple, diagrammaticai sketch of Fig. 1 is a
an embed-la
and therefore reproducible from sample to
ment of the invention and'Fig. 2 is a modi?ca
sample.
tion.
Referring now to the drawing, a material test
ing machine is illustrated as being provided with
two members i and 2 for holding a sample of
the material which is to he tested for tensile
Another object of the invention is the pro
vision of means for controlling the testing ma
chine in such a manner that the application of
load is substantially uniform for all materials
irrespective of their elasticity.
‘
strength. _ Each of the members i and
A still further object of the invention is the
provision of apparatus of the character de
scribed in the foregoing in which the initial rate
may he
a conventional pair of jaws for securely grip
ping the sample.
The lower
mounted on a screw
at which load is imposed on the same is low so
- of jaws 2 i
which is in threaded en
gagement with a nut (not shown) within t
gear box G. The nut is connected through a
gear train and a'chain and sprocket drive t
35 ‘the shaft of an electric motor 6. Although theO
form
In thereof,
carrying a, the
testing
invention
machine
into
is utilizedwhich
effect in.
motor 53 may be of vany suitable type, it is illus
has a ‘pair of members for holding the test
trated as a separately excited
motor.
sample. One of these members is driven by an
' The upper pair of jaws is connected through
electric motor in a direction to apply 'a force to
a chain ‘J to a‘drum t? which is rotatably mount
the sample. Means are provided for producing
on the frame of the machine. ‘Secured to the
a variable reference speed of which the rate of
drum is a pendulum £9 comprising an arm'lla
variation is substantially constant. Additional
having a Weight 921 on the iree'end.
. means are provided for producing a signal volt»
‘in order to cause the load to he applied to the
age which is proportional to the load on the
test ‘sample at a uniform rate, suitable means are
material sample. The difference between the
provided for. comparing the rate of application of
two voltages is utilized to control the motor
that substantially all possibility of shoot: is
eliminated.
'
.
which drives the testing machine to equalize the
rate at which the load is being applied to the
sample with the rate of variation of the reference
voltage. In one speci?c embodiment of the in
vention, a movable member is driven
a con“
stant speed by a synchronous motor, and an
other movable member is driven at a speed hav—
load to the test sample with a'constant refer
ence speed, and utilizing the di?erence to con-'
trol the speed of the motor
so
.
For the purpose of providing an indication of
the rate of application of load tothe test sample,
the‘ slider like of a potentiometer,
is mechani
cally/‘connected, to the pendulum
icy means of
a rod 3 l, a chain it, and a sprocket 53. One end
ing a predetermined relationship to the ratevat
which load is being applied to the test sample. 55 of the rcd?i is provided with a pin Ha which
slides in a slot
in the pendulum arm.‘ The
2,411,450
minal of the armature is connected to bus 22
opposite end of the rod is ‘connected to the chain
which, as pointed out in the foregoing, is con
nected to the center tap of the secondary winde
l2 which engages the sprocket i3 and, at its low
er end, is provided with a weight M. Thus,
whenever the rod ll moves as a result of the
potentiometer slider “la is rotated at a speed
ing 2411. As thus connected, the thyratrons 21
and 28 rectify both half-waves of the alternating
voltage and supply the recti?ed voltage to the
proportional to the speed‘of the rod H.
armature 6b.
counterclockwise rotation of the pendulum 9, the
-
The speed of the motor 6 is adjusted by varying
the average current conducted by the thyratrons.
angular position of the pendulum. Since the
weight of the pendulum remains constant, the 10 Although the thyratrons may be controlled by
any suitable method, vit-is preferred to use the
load on the sample varies with the length of the
method of phase shift control of the grid voltage.
moment arm of the weight 9b about the center of
For the carrying out of this method of control,
the drum 8.. Owing to theslotted connection of
The load on the test sample varies with the '
a phase shifting resistance-reactance network is
rod iii varies in a lengthwise direction approxi 15 provided. This network comprises a secondary
.‘winding 240 of the transformer 24, resistors 30
mately in proportion to the changing length of
and 3!, and capacitors 32 and 33. The resistors
the moment arm of weight 9b. Thus, the posi
and capacitors are connected in series relation
tion of the rod H is an approximate measure of
ship across the secondary winding 240. The cir
the load on the sample, and the speed of the
lengthwise movement of the rod is a measure of 20 cuit is traced from the left-hand terminal of the
secondary winding 240 through resistor 30, ca
the rate of application of load to the test sam
ple. Since the speed of the potentiometer slider , pacitor 32, the common cathode connection 34,
capacitor 33, and resistor 3! to the opposite ter
we is proportional to the lengthwise speed of
minal of the secondary winding 2430.’
the rod II, it is also proportional to the rate of
The common point 360, of resistor 30 and ca
25
application of load to the test sample.
pacitor 32 is connected through a resistor 35 to
The reference speed with which the rate of ap
the grid 210 of thyratron 21. Similarly, the com
plication of load to the sample is compared, is
mon point em between resistor 35 and capacitor
provided by means of a synchronous motor 95
33 is connected through a resistor 36 to the grid
which drives the slider 86a of a potentiometer it
at constant speed. The synchronous motor as is 30 280 of thyratron 28, The capacitativereactance
Xe of the capacitors 32 and 33 is chosen relatively
preferably of the single-phase, self-starting type,
small in comparison with the resistance R of
i. e., the motor starts immediately when it is
resistors 30 and 3E. vThus the alternating volt
connected to a single-phase source such as rep
ages across the capacitors 32 and 33 lag the volt
resented by the supply line H.
age of the secondary winding approximately 90
A limit switch i8 actuated by the pendulum
the rod l I with the pendulum, the position of the
electrical degrees. Since the voltage across the
capacitors 32 and. 33 are applied to the grids 27c
near the beginning of its counterclockwise ro
tation serves to connect the synchronous motor
it to the source it, and a limit switch as which
is actuated by the synchronous motor itself serves
to interrupt the connections of the synchronous
and 280, the voltages of grids 2'30 and 280 lag
the voltages of the anodes Z'la and 28a, respec
40
motor to the source after a predetermined
amount of rotation, [thereby to prevent the slider
i?a from being driven past its end position.
The resistors of the potentiometers iii and it
are connected in parallel with each other and
inseries with the operating coil 2dr: of a line con
tactor 2d across the control voltage buses 2i and
22. A. substantially constant direct voltage is
supplied to the control voltage buses 2i and 22
by means of suitable rectifying means which is
illustrated as a double diode electric valve 28 of
which the anodes 23a. and 23b are connected to
tively, approximately 90 degrees.
. The effect of phase shift of the grid voltage is
produced by ap-plyinga variable component of
direct voltage to the grids in addition to the 90
degree lagging alternating voltage component.
This is accomplished by means of a pair of elec
tric‘ valves 3? and 33 connected in series rela
tionship across the transformer secondary 240.
The valve 3? is preferably a triode valve and the
valve 38 is preferably a diode valve. The circuit
is- traced from the left hand terminal of the
secondary winding 25c to the anode 37a of valve
3?, cathode 37b, potentiometer 86, bus 22, arma
ture 5?), through upper contacts 281) of contactor
opposite terminals of the secondary winding 2%
2B in the closed position thereof to the common
of the supply transformer 2d, and the cathode is
connected to the bus 2i. The bus 22 is connected 65 cathode connection 3%, resistor 39, anode 38a of
valve 38, cathode 38b to the opposite terminal of
by means of a conductor 25 to the center tap of
the secondary winding 260. Thus, the triode
the secondary winding 25a of the supply trans
valve 27 is in parallel circuit relationship with
former. The primary winding 2% of supply
capacitor 32 and the diode valve 38 is in parallel
transformer 25 is connected to a suitable source
‘
of alternating voltage such as represented by the 50 circuit relationship with capacitor 33.1
When the valves 3? and 38 are conducting,
two supply lines 26. As thus connected, the
charges are placed on the capacitors 32 and 33,
valve 23 operates as a full wave recti?er to sup
and as a result, a component of direct voltage
ply a recti?ed voltage to the buses 2i and 22,
is applied to the grids 2'80 and 280. The com
As shown, the separately excited ?eld winding 5d
bination of this direct voltage component with
of the motor 6 is connected across the'buses' 2i
the lagging alternating component produces the
and 22.
,
_
The armature 6b of the motor 5 is supplied
from suitable electric valve means illustrated as
a pair of thyratrons 21 and 28. The anodes 211a .
effect of phase shift of the grid voltage and cor
responding variation of the average current
transmitted by the thyratrons.
and 28a of these thyratrons are connected to op-v 70 The amount of phase shift of the grid voltage
of the thyratrons, and consequently the amount
posite terminals of the. supply transformer sec
of current transmitted by the thyratrons, can be
ondary winding 24a, and the cathodes 21b and
varied by varying the relative conductivities of
28b are connected through conductor 29 and the
the triode valve 31 and the diode valve 38. This
main contacts 20b of contactorZil to one ter
minal of the motor armature 6b. The other ter 75 is ‘accomplished simply by varying the conduc
5
2,411,450
tivity of the triode valve. For this purpose, the
cathode 31b of the triode valve is connected to the
slider 16a of'potentiometer l6, and the control
grid 31c is connected to the slider Illa of poten
tiometer ID.
If the voltage of the grid 31c becomes less neg
ative or increasingly positive with respect to the
voltage of the cathode 31b, the conductivity of
As a result, the grid voltages of the thyratrons
27 and 28 are retarded to such an extent - that’
the thyratrons supply a minimum current to the
armature of the motor 8 which therefore rotates
at a low creeping speed.
I
‘
The direction of rotation is such as to drive the
lower pair oi’ Jaws 2 in an upward direction.
However, as pointed out, the lower pair of jaws
valve 31 is increased. This has the effect of ‘re
tarding the phase of the grid voltage of the 10 2 are in their uppermost position with the clutch
between the motor and the screw 3 disengaged
thyratrons 27 and 28 thereby to decrease the our
so that there is no movement of the jaws at this
rent supplied to thearmature 6b of the motor 6. ‘ point
in the operation.
Conversely, if the grid voltage becomes increas-'
The
test sample is now ?rmly secured in the
ingly negative with respect to the cathode volt
The test run is
age, the phase of the thyratron grid voltage is 15 upper and lower jaws i and
initiated by shifting the lever 55 to engage the
advanced and the current supplied to the arma
clutch to complete the driving connections be
ture is correspondingly increased,
tween the motor '8 and the screw 3. The shift
With the foregoing understanding of the ele
ing of the clutch lever 45 opens contacts 48 to
ments and their organization in the completed
lnterupt the holding circuit for the operating
system, the operation of the system itself will
20 coil of the field contactor 4i. In response to
readily be understood from the following detailed
deenergization, the field contactor drops out to
description. It is assumed that the apparatus is
open its normally open contacts 4lb, 4E0, and Md
in the position in which it is° illustrated in the
and to close its normally closed contacts die and
drawing with the lower jaws 2 in their upper
4i)‘. Contacts 4m in opening interrupt the hold
most position. At the lowermost position of the
lower jaws 2 during the previous test run, the 25 ing circuit for the coil 4la so that the contactor
4! cannot be picked up by a subsequent movement
limit switch 40 which is ‘actuated by the screw
of the lever 435. i
I
3, closed its contacts to complete an energizing
The lower jaws 2 start downwardly at a very
circuit for the operating coil 41a of the ?eld con
low speed to remove the stretch from the sample.
tactor 41. In response to energization, contactor
4| closed its normallyb‘pen contacts 4lb, Me, and 30 When the stretch is completely removed, the
pendulum 9 begins to rotate in a counterclockwise
41d andopened its normally closed contacts Me
direction thereby to apply load to the test sam
and 4|)‘. The opening of contacts Me and 4| f
ple. After a very small amount of rotation oi.’
and the closing of contacts Mia and 4| 0 reversed
the connections of the ?eld winding 6a to pro 35 the pendulum 9, the contacts of a limit switch l8
actuated by the ‘pendulum 9 are closed to com
vide for rotation of the motor 6 in a direction to
plete
an energizing circuit for the operating coil
drive the lower jaws 2 toward their uppermost
47a of a relay 41. In response to energization, the
position. The closing of contacts 41d completed
relay 41 opens its normally closed contacts 4'";
a sealing-in circuit for the operating coil No of
the ?eld contactor 4! in parallel with the con 40 and closes its normally open contacts 4'10. In
closing, the contacts 410 connect the synchronous
tacts of the limit switch 40 so that the contactor
remained picked up after the contacts of the
limit switch 40 opened in response to the upward
movement of the jaws 2.
motor l5 to the source H for rotation in a direc
tion to rotate the slider l6a of potentiometer IS in
a counterclockwise direction.
-
As the slider iGa moves in a counterclockwise
In the uppermost position of the lower jaws 2, 45 direction
along the potentiometer 16, it taps off '
a clutch (not shown) in the testing machine is
and
applies
increasingly positive voltages to the
disengaged to interrupt the driving connection
cathode 31b of the valve 31. As _a result, the,
’ between the motor 6 and the screw 3. Assuming
conductivity of the valve 37 is decreased and
that the motor 6 was stopped with the machine
in this position by pressing the stop pushbutton 50' the phase of the grid voltages of the thyratrons
21 and 28 is advanced. The advance in phase of
switch 42, it is now necessary to restart the motor
the grid voltages of the thyratrons increases the
6. This is done by momentarily depressing the
current supplied to the armature of the motor
start pushbutton switch 43 to close its contacts
6 thereby increasing the speed of the motor 6
and thereby complete an energizing circuit for
also the downward speed of the jaws 2 driven
the operating coil 20a of the line contactor 20. 55 and
thereby.
The increasing downward speed of
In response to energization, the line contactor
the jaws 2 increases the speed of the counter
closes its main contacts 20b and interlock con
tacts 20c and opens its normally closed dynamic _ clockwise rotation of the pendulum 9 so that the
slider Illa of the potentiometer H! which is driven
braking contacts 20d. The contacts 20:1 in open
by the pendulum begins, to overtake the slider
ing interrupt the dynamic braking circuit
l6a of the potentiometer l6 which is driven by
through the dynamic braking resistor 44 in par 60 the
synchronous motor.
allel with the armature, and the main contacts
\
When
the speeds of the two sliders become
2% in closing complete the connections ‘of the
equal, there will be'no further increase in the
armature to the cathodes 21b and 28b of the
thyratrons 21 and 28. The closing of contacts 65 speed of the motor 6. This is an indication that
the rate 'of application of load to the test sample,
200 in parallel with the contacts of the start push
button switch 43 completes a holding circuit for - i. e., the rate of increase of load on the test
sample, is proportionate to the constant speed‘
the operating coil of the line contactor so that
of the slider lSa and is therefore uniform.
the start pushbutton switch 43 may now be re
‘If, owing to some nonuniformity of the sample
leased.
V
.
70
or
other cause, the rate of application of load to
With the sliders Illa and lGa of the potentiom
the test sample should tend to decrease, the slider
eters J0 and IS in the positions in which they
Illa will begin to lag the slider Ilia. The result
are illustrated, the voltage of the grid 310 of the
is that the voltage applied to the grid 310 does
valve 31 is so positive with respect to the voltage
of its’ cathodethat the valveis fully conducting. 75 ‘not increase in a positive direction as rapidly as
the voltage applied to the cathode 31b. Conse
'
acnneo
quently. the conductivity of the valve 31 decreases
thereby to advance the phase of the grid voltage
of the thyratrons 21 and 28 and to increase the
speed of the motor 6. On the other hand, if,
owing to some nonuniiormity in the sample or
other cause, the load on the sample increases at
a rate faster than that determined by the con
stant speed 0! the synchronous motor iii, the slider Illa will lead the slider lea. with the result
carries a pendulum 53 which corresponds to the .
pendulum 9 of the Fig. 1 modi?cation.
When the axis of the rotor coil 49b is at right
angles to the axis of the stator coil 49a, the volt
age induced in the rotor coil is ‘zero.
For all
other positions of the rotor coil, the induced
voltage is proportional to the sine of the angle
between the-axis of the rotor coil and the zerov
position.
The moment arm of the pendulum 53 about the
that the voltage of the, grid 31c becomes in 10 rotational
axis of the drum 52 is proportional
creasingly positive with respect to the voltage
a or the cathode 3112. This increases the conduc
to the sine of the angle between the axis of the
pendulum and the zero or vertical position there
tivity of the valve 31 and retards the phase of
As pointed out in connection with the modi
the grid voltages of the thyratrons-Z'i' and 3:8 ' ‘of.
?cation of Fig. l, the load on the material sample
“thereby to decrease‘the speed of the motor 6.
‘in the testing machine is proportional to the
Thus, the rate oi application of load to the‘test
moment arm of the mn'dulum about its center .
‘of rotation. Owing to the mechanical connec
test.
tion between the rotor coil 4% and the drum
At some point in the downward travel 01 the
52, the rotor coil is rotated through they same
20
lower jaws 2, the test ‘sample is ruptured. At
angle as that through which the pendulum is
the‘ lower end of the downward travel of the
. sample is maintained uniform throughout the
rotated. ‘ Since the'load on the material sample.
jaws 2. the limit switch at closes its contacts to
and the voltage induced in the rotor coil are
complete an energizing circuit for the operating
both proportional to the sine of this angle, the
coil Ma of the ?eld contactor M‘ which. respon
sively to energization reverses the ?eld connec 25 induced voltage is thus a measure of the load
on the material sample.
_ tions of the ?eld_,winding do to the source. This
This voltage is stepped up by means of a trans
reverses thedirection of rotationof the motor ii
;former 5d and recti?ed by suitable means which
and'ca'uses it to drive the screw- t and the pair
is illustrated as a bi-phase half wave recti?er
of jaws 2 in an upward direction. This con
valve
55 of which the anodes 55a and 5512 are
30
tinues until the jaws ‘2 reach their uppermost
connected to opposite terminals of the secondary
position and the clutch in the machine is disen
winding of the transformer and the twin cathodes
gaged to interrupt the driving connections be
55c and 55d are connected through a potentiome
tween the motor 6 and the screw 3.
ter 56 and a ?xed resistor 5'! to the center tap
The vsynchronous motor to continues driving
the secondary winding. The potentiometer 56
the slider iGa until it reaches its limiting posi 35 of
serves for initially adjusting the rectified volt
tion in which the limit switch it opens its con
age across the conductors 5B and 58.
tacts to disconnect the synchronous motor from
The re
mainder of the modification of Fig. 2 is identi
cal with corresponding parts of the modi?cation
itsupper position by means oi.’v a pawl and ratchet
of Fig. 1 and consequently it is omitted from the
40
mechanism (not shown) is manually returned by
the source H’. The pendulum, which is held in
the operator to its initial position.
drawing.
In return- -
limit switch i8_ are opened to deenergize the
operating coil d'la of the contactor 4'5. In re
7
,
-
In connecting the induction voltage regulator
69 in place of the potentiometer iii of Fig. l,
ing to its initial position, the contacts of the
‘ the conductor 58 of Fig. 2 is connected to the
sponse to deenergization, the contactor 8'! drops 45 conductor 60 of Fig. 1 which is connected to the
grid’ 31a of the triode valve 31; and the‘ con
out to open its normally open contacts die and
ductor 59 of Fig. 2 is connected to the conductor
close its normally‘ closed contacts 4%. In clos
iii of Fig. l.
.
ing, the contacts Alb complete the connections
‘The operation of the system of Fig. 2 is iden-m
of the synchronous motor its to the source i‘i
with the operation ofthe system of Fig. 1
through the contacts of a limit switch to and 50 tical
except that the signal voltage proportional to
the reverse ?eld winding/ I50; of the synchronous
load on the material sample is supplied by the
motor i5. In response to this reverse energiza
induction voltage regulator Ml instead of being
tion,‘ the motor it rotates in~the reverse direc‘»
supplied by the potentiometer In of Fig. 1.
tion to return the slider i?a to its initial posi
tion in which the contacts of the limitswitch W 55 Although in accordance with the provisions of
the patent statutes this invention is described
are opened to disconnect the synchronous motor
from the source it. At the beginning of the
reverse rotation, the contacts of the limit switch
i9 are reclosed thereby leaving the system in
60
a reset conditionior a subsequenttest.
as embodied in concrete form and the principle
thereofhas been explained, together with the
best mode in which it is now contemplated
applying that principle, it will be understood that
the apparatus shown and described is merely
illustrative and that the invention is not lim
ited thereto, since alterations and modi?cations
will readily suggest themselves to persons skilled
coiiéi?b. The stator coil is ‘supplied from a suit 65 in the art without departing from the true spirit
of this invention or from the scope of the annexed
able source of alternating voltage which ‘is repclaims.
'
resented in Fig. 2 by the two supply lines 58.
In the modi?cation illustrated in Fig. 2, the
potentiometer it of Fig. 1 is replaced by an induc
tion voltage regulator dB. This regulator has a
stator coil 639a and an inductively related rotor
What we claim as new and desire to secure by
This source may be and preferably is the same
Letters Patent of the United States is:
_
as the single phase alternating voltage source
i. In combination, a material testing machine,
2% of Fig. 1. The rotor member upon which 70
an electric motor for driving said machine to
the rotor coil 6% is mounted is mechanically
apply a load to a material specimen, a reference
connected by means of a shaft 5!], or other suit
able coupling means, to the shaft of the testing
machine drum '52. The drum. 52 corresponds
to the drum 8 of the modi?cation of Fig. 1 and 75
speed device and means responsive to the dif
ference between the speed of said reference speed
device and the rate of application of load to
2,411,450
said material'specimen for controlling said motor
to ‘equalize said rate and said speed.
2. In combination, a material testing machine,
an electric motor for driving said machine to
apply a load to a material specimen, a reference
speed device, means for producing a control volt
?rst mentioned motor to equalize. the speeds of
said sliders thereby to e?ect the application of
load to said specimen at a constant rate.
,
7. In_ combination, a material testing machine
having a pair or members for holding a material
age having a predetermined relationship to the
specimen,’ an electric motor connected to drive
di?erence between the speed of said reference
one of said members, a pivotally mounted pen
speed device and rate of application of load to
dulum connected to the other of said members to
said material specimen, and electric valve means 10 provide for increasing the load on said specimen
responsive to said voltage for controlling said
in response to movement of said motor driven
motor to equalize said rate and said speed.
'
member, means for producing a control voltage
having a predetermined relationship to the dif-v
3. In combination, a material testing machine,
an electric motor for driving said machine ‘to
ierence between the rate or increasing the load on
apply a load to a‘ material specimen, a syn 15 said specimenv at a constant rate comprising a
chronous motor, means responsive to the dife
synchronous motor,,a source of substantially con
ference, between the speed of said synchronous
stant control voltage, a potentiometer having its '
motor and the rate of applicationof load to said
slider connected to be driven by said synchronous
material specimen for producing a control volt
motor and a second potentiometer having its
age, and electric valve means responsive tov said 20 slider connected to be driven in response to move
voltage for controllingsaid motor to equalize said
rate and said ‘speed.
4. In combination, a material testing machine,
ment of said pendulum, and an electric valve pro
vided with an anode,‘a cathode connected to one
' of said sliders and a grid connected- to the other
an electric motor for driving said machine-to ap
of said sliders for controlling the supply of cur
ply a load to a material specimen, a synchronous 25 rent to said ?rst motor to equalize the speeds '
motor, means for producing a control voltage _ of said sliders thereby to eifect application of
having a predetermined relationship to the dif
load to said specimen at a constant rate.
ference between the speed of said synchronous
8. In combination, ‘a material testing machine, _
motor and the rate of application of load to said
an electric motor for driving said machine to
material specimen comprising a potentiometer 30' apply agload to a material specimen, electrical
having its slider connected to be driven by said
means vfor producing a reference voltage varying
synchronous motor and a second potentiometer ,
substantially linearly with time, means respon
having its slider connected to be driven by said
sive to application of load to said material speci
machine at a speed proportional to the rate of
men for producing a signal control voltage sub
application of load to said specimen, and electric 35 stantially proportional to the load on said ma
valve apparatus responsive to said voltage for
terial specimen, and electric valve means respon
controlling said motor to equalize the speeds of
sive
to the di?’erence of said voltages for control
said sliders. >
,
ling said motor to equalize the rates of variation
5. In combination, a material testing machine
of said voltages thereby to effect application of
having a pair of members for holding a material 40 load to said specimen at a constant rate.
specimen, an electric motor connected to drive one
9. In combination, a material testing machine,
of said members, a pivotally mounted pendulum
an electric motor for driving said machine to
connected to the other of said members to provide
apply a load to a material specimen, means for
for increasingly loading said specimen in response
producing a reference voltage having a substan
to movement of said motor driven member, a syn 45 tially constant rate of variation, an induction volt
chronous motor, a ?rst member driven by said
age regulator responsive to application of load
synchronous motor at a constant speed, a second
producing a signal control
member driven in response to movement of said
voltage proportional to said lead, and means re
pendulum at a speed proportional to the speed of
sponsive to the difference of said voltages for con
said pendulum, means for producing a control 50 trolling said motor to equalize the rates 01' varia
voltage having a predetermined relationship to
tion of said voltages thereby to e?'ect application
the di?erence between the speed 01' said ?rst
of load to said specimen at, a constant rate;
member and the speed of said second member, and
10. In combination, a material testing machine,
electric valve apparatus responsive to said control
voltage for controlling said motor to equalize the 55 an electric motor for driving said machine to apply
a load to a material specimen, means for pro
speeds of said ?rst and second members thereby
ducing a reference voltage having a substantially
to cause load to be applied to said specimen at a
constant rate of variation, means for producing
constant rate.
a signal voltage proportional to the load on said
6. In combination, a material testing machine
‘having a pair of members for holding a material 60 material specimen, and means responsive to the
di?erence of said voltages for controlling the motor
specimen, an electric motor connected to drive one
to equalize the rates of variation of said voltages
of said members, a pivotally mounted pendulum
thereby to effect application of load to said mate
connected to the other of said members to pro
rial specimen at a constant rate.
vide for increasing the load on said specimen in
11. In combination, a material testing machine,
response to movement of said motor driven mem 65
an electric. motor for driving said machine to
ber, means for producing a control voltage having
apply a load to a material specimen, an electrical
a predetermined relationship to the diil'erence
device for producing a reference voltage having a
between the rate of increasing the load on said
substantially constant rate of variation, means
specimen and a constant rate comprising a syn-1'
responsive to the application of load to said mate
chronous motor, a potentiometer having its slider 70 rial
specimen for producing a signal control volt
connected to be driven by said synchronous motor
age having a rate of variation proportional to- the
and a second potentiometer having its slider con
rate of application of load to said material speci
nccted to be driven in response to movement of I
said pendulum, and electric valve means respon
men and means responsive to the difference of
sive to said control voltage for controlling said 75 such voltages for controlling said motor to equalize
the rates of variation of said voltage thereby to
QAZEAEQ
e?ect application 0! load to said specimen at a
of said reference‘ voltage and said signal voltage
thereby to effect application of load to said speci
constant rate.
men at a substantially constant rate.
having a pair of members for holding a material
specimen, an electric motor connected ‘to drive
one of said members, a pivotally mounted pen
chine comprising an electric motor for applying a
load to a material specimen, a source of reference
12. In combination, a material testing machine ‘
1%. Control apparatus for a material testing ma- ,
predetermined rate of
application of load to said material specimen,
to provide for increasingly loading said specimen
means for producing a signal voltage correspond
in response to movement of said motor driven
ing to the rate of application of load to said speci
m
member, means for producing a reference voltage
men by said motor, and means responsive to the
having a substantially constant rate of variation,
di?erence of said voltages for controlling said
an induction voltage regulator driven by said
motor to equalize said rates.
pendulum for producing a signal control voltage
15. Control apparatus for a material.testing
proportional to the load on said‘ material speci
machine
comprising an electric motor for applying
15
' dulum connected to the other of said members
‘ voltage corresponding to a
men, and electric valve means responsive to the
diiference of said voltages for controlling said
motor to equalize the rates of variation of said
voltages thereby to effect application of load to
said specimen at a constant rate.
13. In combination, a material testing machine
having a pair of members for holding a material
specimen, an electric motor connected to drive one
of said members, a pivotally mounted pendulum
connected to the other of said members to provide
for increasingly loading said specimen in response
to movement of said motor driven member, elec
a load to a material specimen, a source of refer
ence voltage, means for producing a signal volt
age corresponding to the rate of application of
load to said specimen, and electric valve means
responsive to the di?erence of said voltages for
controlling said motor to maintain the rate of
application of load to said specimen constant.
16. Control apparatus for a material testing
a
, machine‘ comprising an electric motor for apply
ing a load to a material specimen, a source of
as
reference voltage corresponding to a predeter
mined rate of application of load to said specimen,
means comprising an induction voltage regulator
trical means for producing a direct reference volt
age having a substantially‘ constant rate of varia
responsive to the load appliedto said specimen
for producing a signal voltage corresponding to
the rate of application of load to said specimen
tion, an induction voltage regulator I driven by
said pendulum for producing an alternating volt
age having an e?ective value proportional to the
load on said specimen, means for rectifying said
alternating voltage to produce a direct signal con
trol voltage proportional to said load, and electric
and electric valve means responsive to the diifer
- ence of said voltages for controlling said motor to
valve means responsive to the dl?erence of said 35
reference voltage and signal voltage for control
ling said motor to equalize the rates of variation
'e?ect application of load to said specimen at said
predetermined rate.
CHARLES E. MILLER.
RQBERT J. DEMARTINI.
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