IMPROVEMENTS IN MACHINERY OR APPARATUS FOR TESTING STRAIN OR PRESSURE APPLIED TO SOLID BODIES AND FOR OTHER LIKE PURPOSES
Year: 1870

page_text: PROVISIONAL SPECIFICATION left by William Robert Lake at the
Office of the Commissioners of Patents, with his Petition, on the
7th June 1870.-A communication from abroad by Jules Auguste
Desgoffe, of Paris, in the Empire of France, Engineer.
I, WILLIAM ROBERT LAKE, of the International Patent Office,
Southampton Buildings, London, Consulting Engineer, do hereby declare
the nature of the said Invention for "IMPROVEMENTS IN MACHINERY OR
APPARATUS FOR TESTING STRAIN OR PRESSURE APPLIED TO SOLID BODIES AND FOR
OTHER LIKE PURPOSES," a communication, to be as follows:-
The improvements which form the subject of the present Invention
relate to a machine or apparatus whose distinguishing peculiarity is that
it allows the easy reading with mathematical precision and at any
moment during its operation of the effect of tension, deflection, com-
pression, penetration, or expansion exerted upon a solid body subjected
to the action of the machine.
I will first describe the said machine as adapted to the testing of a
solid under longitudinal tension. A cast-iron bed serves for the support
of the principal working parts of the machine. At one of its extremities

page_text: a screw...
is fixed a poppet or head wherein is fitted a nut through which is passed
The said nut has a flange or rim formed with teeth to gear
with an endless screw or worm mounted on the shaft of a fly wheel.
At the other end this shaft terminates with a square part adapted to
receive a crank or handle whereby the apparatus is operated. The said
screw is connected at one end to a block to which is jointed a pair of
pincers for holding the end of the wire, bar, cable, or other article to be
tested. The other end of such article is held between the jaws of another
similar pair of pincers jointed to another block.
The latter is sup-
ported upon the short arm of a rectangular two-armed lever by a steel
knife edge.
The aforesaid lever oscillates upon a knife edge which has its support
upon two ribs of the bed. The long arm of the rectangular lever has a
similar knife edge which bears upon the extremity of a rod whose other
end is immovably connected with a plate which governs the operation
of the indicating apparatus. This instrument consists of a reservoir
filled with liquid and hermetically closed by a flexible cover or diaphragm
of india-rubber or other suitable material. This reservoir is in direct
communication through a tube with a bulb (filled with mercury)
forming part of a gauge whose divisions correspond with the different
strains produced by the operation of the windlass.
It will be readily understood that if the fly wheel shaft is turned in
such a direction that through the worm the nut is caused to force the
horizontal screw outward a tensile strain will be exerted on the pincers
which will be immediately transmitted to the knife edges and through
the rod to the plate which rests on the flexible cover or diaphragm and
acts directly upon the body of liquid in the indicating apparatus.
The pressure will cause the ascension of the mercury in the tube whose
graduations will give the exact intensity of the strain. The pincers
being furnished with small pointers which pass over a scale of metrical
divisions on the bed it is obviously very easy to measure the elongation
of the body being tested, while at the same time the value of the strain
in pounds or other quantities can be read upon the tube of the gauge.
It will be readily understood that I can substitute for the plate and
flexible cover above mentioned a combination of differential pistons
acting directly upon the mercury or other liquid of the indicating
apparatus.

page_text: In applying the said machine to the testing of the penetration or
hardness of solids, I modify the arrangement of its parts as follows:-
Upon a suitable bed or base are placed the winch for producing the
strain and the gauge for showing its intensity. To determine the strain
I turn the fly wheel by its handle thereby actuating the screw, and by
the nut advancing a cylinder which is guided in the bed or base.
The said cylinder carries at its outer extremity a point of any desired or
convenient form and size according to the hardness of the body or
substance, and whose object is to penetrate the said body or substance.
The latter is arranged between the said point and the surface of a block
which rests against a knife edge attached to a bar the latter oscillates
upon another knife edge and is extended to form a lever whose extremity
rests upon a third knife edge which is fixed on the plate placed over
the flexible membrane or diaphragm of the indicating apparatus. The
bed or base is made hollow to form a reservoir for the mercury, and has
a tube or channel bored to form a means of constant communication
between the said reservoir and the tube of the gauge.
If the solid substance or object to be tested is placed as above stated
between the point and the block face, and the fly wheel is turned in the
proper direction to advance the cylinder the point will penetrate the solid,
and the strain exerted reacting upon the knives will act without loss upon
the plate over the diaphragm, that is to say, upon the liquid mass which
will rise proportionately in the graduated tube.
In some cases the aforesaid machine when used for the testing of the
ductility of bodies is modified in the following manner :-The knife
edges are dispensed with. The solid to be tested has its two ends fixed
to the pin of a block fixed on the piston rod of a pump, and to another
pin attached to a vertical plate. The strain is produced by forcing
liquid into this pump by means of suitable compressing apparatus
connected with the fly wheel, which is geared by bevelled pinions with
a shaft having two handles. The aforesaid vertical plate is fitted upon
another plate, which forms the supporting plate and the reservoir for
the liquid. The pump is attached to the supporting plate by tie rods.
The pressure of the liquid in the reservoir is transmitted through a
tube to the bulb of the gauge. I also apply my Invention to the
verification of the graduation of metallic gauges for high pressures and
to the testing of gun barrels and tubes which have to withstand internal

page_text: pressure.
For these purposes the machine is modified in the following
manner: The pressure is produced by a piston forced into the barrel
of the press by the action of the fly wheel which is keyed upon a gun
metal sleeve. The interior of the sleeve is formed with screw threads,
and the head of the piston has screw threads which work in those of
the sleeve. The screw head of the piston has three branches through
which pass guide rods, that prevent the turning of the piston. These
rods are fixed at the other end to a washer. Upon the body of the
press are fixed the gauge which indicates the pressure exerted upon
the liquid contained in the cylinder, and a coupling link to which is fixed
the barrel or tube to be tested. The upper end of the barrel or tube
is closed by a cylindrical rod, which is supported against a head or
block secured immovably to the machine by the rods of the coupling,
which at their lower ends are fitted to turn upon a cross pin. The
lower end of the barrel or tube is inserted into a socket which forms
part of the coupling, and is attached to the press by a joint, this joint
is made tight by a steel piece within which is enclosed a lining of gutta
percha.
Instead of indicating the pressure by an ordinary gauge arranged as
above described, a tube may be connected with the interior of the body
of the press to communicate through a cast-iron block with a chamber
in which is placed a small piston. The said piston forms part of the
plate which as herein-before described is placed over the flexible cover
or diaphragm of the reservoir. The latter is in communication with the
graduated tube of the gauge.
For testing compression the pressure is communicated to the ram or
plunger of the press by forcing in liquid with a pump and by means of
a small piston connected to the fly wheel. In this modification of my
Invention the construction of the pump is peculiar. The piston is of
varying diameter. The large part fits and works in the pump barrel
and the small part works through a guide communicating with a
cistern containing the liquid to be forced under the ram. The small
part of the differential piston has a small central hole opening inside
the cylinder through small perforations. The object of this arrangement
is to dispense with valves. These small holes are opened and closed
as the pump is operated by passing through the packing of the guide,
and the liquid is forced through a pipe or passage into the body of the
press.

page_text: The body to be tested is placed between the ram and the block or
head of the press. The said block is connected to the body of the press
by framework with circular ends, whereby the weight of the apparatus
is diminished.