Improvements in Hydrostatic Weighing-machines, Weigh-bridges, and the like.
Year: 1891

page_text: Date of Application, 14th Apr., 1891
Complete Specification Left, 11th Dec., 189:-Accepted, 14th July, 1892
PROVISIONAL SPECIFICATION.
Improvements in Hydrostatic Weighing-machines, Weigh-bridges,
and the like.
We, Jons JACKSON, Engineer, and EDWIN ALFRED HOAD, Manufacturer,
both of Suffolk House, Laurence Pountney Hill, in the City of London, do hereby
declare the nature of this invention to be as follows:--
Our invention relates to hydrostatic weighing-machines weighbridges and the
like, and is designed to simplify and improve the construction of the same.
Heretofore it has been usual to construct such weighing-machines with a piston
or plunger arranged to move up and down in a cylinder, the liquid being contained
in the space between the said piston or plunger and the bottom of the cylinder.
Weighing-machines constructed in this manner are objectionable by reason of the
difficulty of keeping them tight and preventing leakage, and also by reason of the
fact that the devices employed to form fluid-tight joints between the relatively
movable parts of the machine, cause more or less friction, which interferes with the
proper working of the machine and consequently impairs the accuracy of its
indications.
Now according to our present invention, we enclose the liquid in a vessel or box
which is bermetically sealed, and one or more parts of which can be forced inward
to a greater or less extent by pressure applied to it externally, so as to subject the
liquid contained in it to a corresponding pressure, which is transmitted to a gauge
of any suitable description connected with the said closed vessel or box. We are
thus enabled to dispense with the piston or plunger hitherto employed, and also
with the cup-leathers or similar devices heretofore used for making fluid-tight
joints between the relatively movable parts. The said closed vessel or box is
combined with suitable devices through the medium of which the body or object
to be weighed will exert upon the liquid more or less pressure according to its
weight.
We provide for the connection of the said vessel or box with a small accumulator
or pump whereby liquid may be forced into the said vessel or box until the latter
is completely filled, or until an initial pressure is set up therein. This accumulator
or pump may be used from time to time, if required, to introduce more liquid into
the said vessel, and thus ensure the proper action of the machine.
We find it advantageous to make the said closed vessel or box in the form of a
short cylinder the upper end of which consists of a more or less flexible or elastic
metallic diaphragm. Or both the upper and the lower ends of the said cylinder
may consist of flexible or elastic metallic diaphragms.
In constructing a suspended weighing-machine in accordance with our said
invention, the closed vessel or box is attached to or supported in a suitable loop or
frame whereby it may be conveniently suspended from a crane-chain or from a fixed
hook or the like; and a circular piece or disc of metal or other suitable material is
placed upon the diaphragm or top of the said vessel. Upon this circular piece or
disc bears a rod which is suitably connected with a hook or the like for supporting
the body or object to be weighed. The gauge is preferably secured in a recess or
cavity formed in the side or wall of the said vessel or box, and is connected with the
said vessel by a suitable pipe.
In applying our invention to a weighbridge, the closed vessel or box is mounted
upon a suitable foundation or standard, and the platform is conveniently supported
upon the circular piece or disc on the diaphragm or top of the closed vessel
or box.
It is obvious, however, that the construction of our improved weighing-machine

page_text: or weighbridge can be modified to some extent without departing from the nature
of our said invention.
It will be seen that, in our apparatus, the pressure is imparted to the liquid by
the forcing inward to a greater or less extent of one or more flexible or elastic
diaphragms forming parts of the closed vessel or box, instead of by the movement
of a piston or plunger in a cylinder, as in the hydrostatic weighing-machines
heretofore employed. There is therefore, in our apparatus, much less friction and
less liability to leakage than in the machines heretofore employed.
Dated this 13th day of April 1891
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicants.
COMPLETE
SPECIFICATION.
Improvements in Hydrostatic Weighing-machines, Weigh-bridges,
and the like.
We, JOHN JACKSON, Engineer, and EDWIN ALFRED HOAD, Manufacturer,
both of Suffolk House, Laurence Pountney Hill, in the City of London, do hereby
declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement :-
Our invention relates to hydrostatic weighing-machines, weigh-bridges and the
like, and is designed to simplify and improve the construction of the same.
Heretofore it has been usual to construct such weighing-machines with a piston
or plunger, to which the load is to be applied, and which is arranged to move up
and down in a cylinder containing glycerine or other suitable liquid in the space
between the said piston or plunger and the bottom of the said cylinder, this space
being in communication with a pressure-gauge for indicating the weight of the
load.
Weighing-machines constructed in this manner are objectionable by reason of the
difficulty of keeping them tight and thus preventing leakage, and also by reason of
the fact that the devices employed to form fluid-tight joints between the relatively
movable parts of the machine, cause more or less friction, which interferes with the
proper working of the machine and consequently impairs the accuracy of its
indications. Such friction is more especially objectionable because it prevents the
return of the parts to the proper position to accurately record the weight of the
load, should they be moved beyond this position by any shock or jerk due to the too
sudden application of the load.
Now according to our present invention, we obviate the defects and inconveniences
above mentioned, by enclosing the liquid in a hermetically sealed vessel or box of
peculiar construction, which is in communication with a suitable pressure-gauge.
This vessel or box is constructed with one or more flexible or elastic diaphragms, so
arranged as to be forced inward to a greater or less extent by pressure applied
thereto externally by the load; the liquid contained in the said vessel or box is
thus subjected to a corresponding pressure, which is transmitted to the said gauge.
We are thus enabled to dispense with the piston or plunger hitherto employed, and
also with the cup-leathers or similar devices heretofore used for making fluid-tight
joints between the relatively movable parts of the machine. The said closed vessel
or box is combined with suitable devices through the medium of which the pressure
due to the weight of the load will be transmitted to the flexible or elastic diaphragm
or diaphragms.
We find it advantageous to provide for the connection of the said closed vessel or
box with a small accumulator or pump, whereby liquid may be forced into the said
vessel or box until the latter is completely filled, or until an initial pressure is set
up therein. This accumulator or pump may be used from time to time, if required,

page_text: the machine.
In the accompanying drawings, we have shewn how our said invention may be
conveniently and advantageously carried into practice.
Figure 1 is a front elevation, and
Figure 2 a side elevation of one form of our improved weighing-machine
adapted to be suspended from a crane-chain or from a fixed hook or the like.
Figure 3 is a vertical section on the line, Figure 1.
Figure 4 is a vertical central section illustrating another modification of our
invention, and
Figure is a sectional elevation illustrating a further modification of our said
invention.
Like letters indicate corresponding parts throughout the drawings.
a indicates the hermetically sealed vessel or box in which the glycerine or other
liquid is contained-- is the pressure-gauge which is in communication with the
said vessel or box through a suitable pipe . The vessel or box a is closed at its
upper end by means of a more or less flexible or elastic metallic diaphragm a'. The
said vessel or box is provided with a suitable loop or frame whereby it may be
conveniently suspended from a crane-chain or from a fixed hook or the like. An
annular piece or dised of metal or other suitable material is placed upon the
diaphragma and is provided with a hollow or tubular rod or stem d'. A rod a
extends through the stem and through the said annular piece or disc and bears at
its lower end against the centre of the said diaphragm a'. The said rod is
formed with a shoulder (Figure 3) adapted to bear against the upper end of the
stem when the said rod has been moved downward through a predetermined
distance. To provide for varying this distance as may be required, we find
it advantageous to make the rod in two parts which are united by a screw-
thread as shown, so that they can be adjusted relatively to each other, or so
that they can be detached to permit the insertion between the stem and the
shoulder d, of one or more washers of greater or less thickness for the purpose
of regulating or determining the distance through which the rod must be
moved before its shoulder will act upon the stem and depress the annular
piece or disc d. The lower part of the rod is reduced in diameter to permit
of its being passed through the stem d. The said rod d is arranged beneath a
cross-bar e firmly connected to two side rods working in guides 7, '. The rods f
are firmly secured at their lower ends in a cross-bar provided with a hook k or
other suitable device for supporting the body or object to be weighed.
When a load is suspended from the hook k, the weight of the said load acts
through the medium of the cross-bar j, the sido rods, the cross-bar e and the
rod d² and annular piece or disc d, upon the diaphragm a, and thus subjects the
liquid in the vessel or box a to more or less pressure according to the weight of
the said load. This pressure is communicated to the gauge b, which is thus caused
to indicate such weight.
By the above described arrangement of the annular piece or disc d and the
central rod in combination with the diaphragm a', we provide for obtaining the
requisite pressure upon the surface of the liquid in the closed vessel or box, without
subjecting the diaphragm to undue stress, the rod first acting upon the centre of the
diaphragm, and pressing it inward more or less according to the relative adjustment
of the two parts of the said rod, and the shoulder d then acting upon the stem d',
so that pressure is applied to the diaphragm both through the said disc d and
through the rod d².
m is a pipe for connection with an accumulator or pump, for the purpose of
charging the vessel or box a with liquid. This pipe is provided with a valve m'
for tightly closing the vessel or box a prior to the disconnection of the same from
the accumulator or pump.
A cap or cover 9 is provided for protecting the said
pipe and valve.
In applying our invention to a weigh-bridge, the closed vessel or box is mounted

page_text: upon a suitable foundation or standard, and the platform is conveniently supported
upon a circular or annular piece or disc on the diaphragm or top of the closed vessel
or box, or upon a central rod such as that shewn in the drawings.
It will be seen that, in our improved weighing-machine, the pressure is imparted
to the liquid by the forcing inward to a greater or less extent, of one or more flexible
or elastic diaphragms forming parts of the closed vessel or box, instead of by the
movement of a piston or plunger in a cylinder, as in the hydrostatic weighing-
machines heretofore employed. There is, therefore, in our apparatus, no appreciable
amount of friction and at the same time less liability to leakage than in the machines
heretofore employed.
It is obvious that the construction of our improved weighing-machine can be
somewhat modified according to the purpose for which it is required without
departing from the nature of our said invention.
In Figure 4, we have illustrated a modification of our said invention wherein we
combine, with the annular piece or disc and the rod d, another annular piece or
disc d' surrounding the disc d and also adapted to bear upon the flexible or elastic
diaphragm. The disc is provided with a hollow or tubular stem through
which extends the stem of the disc d. The parts are so arranged that when a
load is applied to the machine, the rod d² will be depressed and will act upon the
diaphragm, and, after the said rod has moved downward through a predetermined
distance, its shoulder will act upon the stem and depress the disc d; moreover,
when this disc and the rod have been moved downward through a predetermined
distance, the said shoulder will act upon the stum and the three parts d, d, d'
will be pressed downward upon the diaphragm. If desired, the device which acts
directly upon the diaphragm may be formed of a larger number of pieces, so as to
render its action upon the diaphragm still more gradual, suitable means being
provided, if deemed advantageous for permitting relative adjustment of the said
pieces for the purpose above specified. Or the said device may consist of a single
piece.
According to a further modification of our said invention we make the flexible
or elastic diaphragm comparatively thin at the central portion thereof and gradually
increasing in thickness from the said central portion to its circumference, as shown,
for example, in Figure 5. In this case, we can use a single rod arranged to
bear against the central portion of the said diaphragm, the outer portion thereof
being sufficiently strong to resist the internal pressure without extrinsic support.
In machines for weighing very heavy loads, if only a single flexible diaphragm
were employed, it might be necessary, in order to give the said diaphragm the
requisite strength, to make it of such thickness that its flexibility would be impaired.
In some instances, therefore, instead of using only a single diaphragm, we provide
for obtaining the requisite strength and flexibility by employing two or more flexible
diaphragms arranged one above another.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is ―
First. A hydrostatic weighing-machine so constructed that the load acts upon
the liquid through the medium of one or more flexible or elastic diaphragms,
instead of through a movable piston or plunger.
Second. The combination, with the Hexible or elastic diaphragm forming part
of the closed vessel or boy, of a device consisting of two or more part or piece-
working one within another and arranged to act in succession upon the said
diaphragm, with or without means for varying the relative movement of the said
parts or pieces, substantially as, and for the purposes, above specified.
Third. The improved hydrostatic weighing-machine constructed substantially as
described with reference to Figures 1, 2 and 3 of the drawings and operating as
above specified.
Fourth. The modification of our invention wherein we employ a flexible or

page_text: elastic diaphragm the thickness of which increases from the centre to the circum-
ference, substantially as described with reference to Figure 5 of the drawings, for
the purpose above specified.
Dated this 11th day of December 1891
D. Young & Co.,
JOHN JACKSON.
EDWIN A. HOAD.
11 & 12, Southampton Buildings, London, W.C., Agents for the Applicants.