An Improved Machine for Testing Tensile and other Strains.
Year: 1885

page_text: An Improved Machine for Testing Tensile and other Strains.
"
I, GEORGE HENRY DENISON of North Street, Leeds, in the County of York,
Machinist, do hereby declare the nature of my said Invention for AN IMPROVED
MACHINE FOR TESTING TENSILE AND OTHER STRAINS," to be as follows:-
The object of this Invention is the production of a Testing Machine wherein,-
by the automatic action of the travelling or otherwise progressively. increasing
testing weight, both as regards its motion, and instantaneous stopping at the
moment of fracture of the material being tested, and the automatic stopping of the
main stretching force also,-greater accuracy, with less care and skill from the
operator are obtained; and it may be thus described :-
:-
I first construct the bed or "sole plate" of my machine, which consists, by
preference, of a strong metal casting or other equivalent, of the form, in plan, of
the letter T or thereabout; and upon this, just within the line of what may be
called the cross piece or face, I fix, in a firm and substantial manner, the main
standard, which is so constructed that the upper portion can rise and fall tele-
scopically, by means of a "dovetail," or a cylindrical or other fitting, and a screw
or other steady and powerful equivalent, and any convenient or desirable power
for actuating the same.
The upper, sliding, or travelling portion of this standard is fitted to carry the
main graduated lever, upon centres, after the manner of a weighing machine lever,
and at the rear of these, I fix the strain or tension centres and rod, for giving the
upward pull or strain upon the material to which the test is required and applied;
the centres, clips, or other equivalent for holding down the material under treatinent,
being fixed upon the cross piece or face of the sole plate, in such positions as
circumstances may require.
I now construct, and fit to slide or run, upon the said main graduated lever, in
a perfectly smooth and steady manner, the movable or progressive testing weight,
and this I propel, automatically, by weight or spring as the case may require ;-
the steady, predetermined, rate of travel being regulated or "governed" by means
of light revolving fliers, in connection with a train of wheels and pinions for
driving the same; the automatic stopping action or arrangement being applied, by
preference, as a break to one of the revolving shafts or wheels of the said wheel
train or motion, and also, as a stop,-by stud or pin,-to the governing fliers; the
former coming into action, a moment before the latter, to lessen the blow or
concussion, whilst still allowing the precision and accuracy of the latter,

page_text: "
In constructing the automatic stopping arrangement to the main standard and
stretching action, I employ an adjustable friction clutch and a fine toothed ratchet
wheel and click or pawl," in addition to a slack driving cord or belt action, with
a third pulley, upon a lever, under the control of the operator, for regulating the
pressure, tension, and grip; the ratchet wheel and click or pawl action being
prevented from taking effect, and therefore the friction clutch being inoperative,-
before the commencement of the test and strain, by means of an eccentric stop
and handle, or other equivalent, under the free end of the graduated lever; and
afterwards, during the test, before the moment of fracture, by means of an inter-
mediate yielding stop, underneath the said lever, which whilst allowing the
necessary "play" or freedom to the lever, (between the said intermediate stop and
the upward stop) during the test, or whilst the tension is upon the material, being
tested, shall yield to the greater weight and force which the fracture or breaking
of the tested material allows to come upon it, and then cause the ratchet wheel
and click, to take effect, and instantaneously stop the action of the whole; the
extent of deflection or elongation, being indicated upon a vertical graduated index,
in the usual manner.
An Improved Machine for Testing Tensile and other Strains.
I GEORGE HENRY DENISON, of North Street, Leeds, in the County of York,
Machinist, do hereby declare the nature of my Invention for "AN IMPROVED
MACHINE FOR TESTING TENSILE AND OTHER STRAINS," and in what manner the
same is to be performed, to be particularly described and ascertained in and by
the following statement :-
.
The object of this Invention is the production of a Testing Machine, wherein,
by the automatic action of the travelling or otherwise progressively increasing
testing weight, both as regards its motion, and instantaneous stopping at the
moment of fracture of the material being tested, and the automatic stopping of the
main stretching force, also greater accuracy with less care and skill from the
operator are obtained, and it may be thus described,―
I first construct the bed or "sole plate" of my machine, which consists, by
preference, of a strong metal casting or other equivalent, of the form, in plan, of
the letter or thereabout, and upon this I fix in a firm and substantial manner,
the main standard, which is so constructed that the upper portion can rise and fall
telescopically by means of a dove-tail, cylindrical or other fitting, and a screw or
other steady and powerful equivalent, and any convenient or desirable power for
actuating the same.

page_text: The upper, sliding or travelling portion of this standard is fitted to carry the
main graduated lever upon centres, after the manner of a weighing machine lever
or steelyard, and at the rear of these, I fix the strain or tension centre and rod for
giving the upward pull or strain upon the material to which the test is required
and applied; the centres, clips, or other equivalent for holding down the material
under treatment, being fixed upon the cross piece or face of the sole plate in such
positions as circumstances may require.
I now construct and fit to slide or run upon the said main graduated lever, in a
perfectly smooth and steady manner, the movable or progressive testing weight or
counterpoise, and this I propel automatically by weight or spring as the case may
require, the steady predetermined rate of travel being regulated or governed by
means of light revolving fliers in connection with a train of wheels and pinions
for driving the same; the automatic stopping action or arrangement being applied,
by preference, as a break to one of the revolving shafts or wheels of the said wheel
train or motion, and also as a stop,-by stud or pin,-to the governing fliers; the
break coming into action a moment before the fliers are stopped to lessen the blow
or concussion upon the latter whilst still allowing the precision and accuracy of the
action of the latter.
In constructing the automatic stopping arrangement to the stretching action,
I employ a countershaft driven from any convenient line shaft and carrying a fast
and a loose pulley; the belt or strap which drives the countershaft is under the
control of a belt guide, the said guide being movable so as to divert the strap from
the fast to the loose pulley and vice-versa. When the strap is running upon the
fast pulley, the stretching action is at work and when the test piece breaks, I cause
the strap to be instantly diverted to the loose pulley by the following means,-
I make the support, or rest at the free end of the lever or steelyard in the form of
an elbow crank and connect the lower end of this crank by a series of rods and
joints to the belt guide in such a manner that the said support or rest is com-
paratively firm whilst the test is being carried on, but when the fracture of the
test piece occurs, it shall be moved by the weight of the lever or steelyard suddenly
falling upon it, and thus move the belt guide, causing the strap to be moved to
the loose pulley and the stretching motion stopped.
In the accompanying illustrations,-Figure 1 is a front elevation of the machine
showing a cast iron bar, one inch square in position to be tested transversely ;
Figure 2 is a plan of the same; Figure 3 is an enlarged view of the train of wheels
and fliers constituting the governing and stopping, mechanism, and Figure 4 is a
reverse elevation of the machine without the beam or steelyard, showing details of
the mechanism used to stop the stretching or straining motion upon the fracture of
the test piece when the machine is driven by belt, and in all these a is the bar or
piece to be tested, b. is the connecting rod which transfers the strain to the knife-
edged centre c. of the lever or steelyard d. The lever itself rests in equilibrium
upon a knife-edged centre c. when the travelling weight or counterpoise f. is run up
to the shoulder or starting point. The falling weight g. causes the weight ƒ to
travel by means of the cord or chain shown, which cord or chain also drives the
train of wheels and fliers constituting the governing and stopping mechanism
shown at h. in Figs. 1 and 2 and in detail in Fig. 3. In Figure 3. n, is the chain
or cord driving the wheel o. and the spur wheel q. keyed to the same shaft p; the
wheel q drives a small spur wheel or pinion not seen in drawing, which is keyed -
fast to shaft r, the said shaft also carrying a spur wheel 8 which drives the fliers
by means of a pinion not seen in the drawing. The dotted lines show the position
of the brake t. which projects slightly below the lower edge of the steelyard and
is pressed against the wheel s. by the weight of the steelyard when the test piece
breaks. u is a support or rest to keep the end of the steelyard in position when
it is not in equilibrium. v is the stop against which the fliers strike when the
steelyard descends below its equilibrium point. The wheel i actuates a worm,
wormwheel and screw which lifts the upper part of the standard carrying with
it the lever or steelyard and so causing a strain upon the test piece through the

page_text: rod b. The amount of deflection is ascertained by means of a sliding scale or
vernier k. fixed upon the moving part of the standard. Z. is a catch to retain the
weight when the machine is being balanced or when not in use.
screw to regulate the equilibrium of the lever or steelyard.
m. is the balance
The action of the machine is as follows, the piece to be tested having been placed
in position in the clips, and the vernier or scale on the standard set to zero, the
wheel is turned either by hand or belt causing the upper part of the standard to
rise this causes a tension between the test piece and the back knife edged centre c.
which tilts up the free end of the lever or steelyard and releases the fliers from the
stop v (Fig. 3) thus allowing the train of wheels to revolve and the weight ƒ to
travel forward which it will continue to do until it gains sufficient power to over-
come the strain on the test piece and causes the steelyard to descend again until
the fliers engage with the stop v and the motion of the weight is stopped until
further strain is put on the test piece. When the test piece breaks, the free end
of the steelyard falls with considerable weight upon the support u. which being in
the form of a crank, exerts a pull in the direction shown by small arrows (Fig. 4)
upon the rods and cranks connected to the belt guide causing the belt to be
instantly diverted to the loose pulley and the straining motion stopped.
Having now particularly described and ascertained the nature of my said
Invention, and in what manner the same is to be performed I declare that what
I claim is
First. The automatic governing and stopping of the travelling test-weight or
counterpoise whereby it is made to continually balance and indicate the amount of
strain upon the test-piece, and
Second. The automatic stopping of the straining motion at the instant of fracture
of the test piece whereby the deflection or extension of the same is accurately
registered, substantially as and after the manner herein described and set forth.
Dated this 27th day of October 1885.