Improvements relating to Weighing-machines.
Year: 1891

page_text: COMPLETE SPECIFICATION.
Improvements relating to Weighing-machines.
We, JOHN JACKSON, Engineer and EDWIN ALFRED HOAD Manufacturer, both
of Suffolk House Laurence Pountney Hill in the City of London do hereby
déclare 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 weighing-machines, and is chiefly designed to improve
the construction of hydrostatic weighing-machines, that is to say weighing-machines
wherein the load exerts more or less pressure upon a body of liquid and acts
through the medium of such liquid upon a pressure-gauge which indicates the
weight of the load.
When a heavy load is suddenly applied to a weighing-machine of this kind or
class, it subjects the pressure gauge to undue stress and is apt to thus injuriously
affect the same so as to impair its action or the accuracy of its indications. The
index or pointer of the pressure-gauge is, in this manner frequently moved through
an angle far greater than is necessary, and has to return through a considerable
fraction of this angle in order to accurately indicate the weight of the load.
some of the hydrostatic weighing-machines heretofore constructed, such excessive
movement of the weighing-mechanism presents the further disadvantage that, by
reason of the friction, the moving parts cannot return to the proper position and the
weight of the load is, consequently, inaccurately recorded by the gauge.
In
Now our invention is designed to obviate these defects. And we accomplish
this result by the employment of one or more supports the position of which can be
regulated in such a manner that they will sustain any excessive stress due to the too
sudden application of the load, the downward force exerted by the load being resisted
by the said support or supports when the index or pointer of the pressure-gauge
has been moved through the required angle, or, if desired, through an angle slightly
greater than that required to indicate the weight of the load; such excessive stress
will, therefore, not be exerted upon the weighing-mechanism. In this manner, we
provide for regulating or determining the maximum stress to which the weighing-
mechanism shall at any time be subjected. For instance, if the machine is adapted
for weighing loads up to say five tons, the supports are so arranged that they will
protect the weighing-mechanism against any stress greater than that due to a weight
of five tons, and, when the inachine is required for loads of a lesser weight, the said
supports can, if desired, be so adjusted as to relieve the weighing-mechanism from
any stress greater than that due to such lesser weight.
Our
Our said invention is very advantageously applicable to machines to be suspended
from a crane-chain for the purpose of weighing loads lifted by the crane.
said invention is, however, also applicable to weigh-bridges and other forms of
weighing-machines.
In the Specification of a former application for Letters Patent dated 14th April
1891, No. 6338, we have described a weighing-machine of peculiar construction
wherein the weight of the load acts upon a diaphragm forming the top of a closed
vessel or box which is filled with liquid and is in communication with a pressure-
gauge. Our present improvements have been designed chiefly with the object of
providing for the protection of such weighing-machines against any excessive shock
or jar to which they might otherwise be subjected by the too sudden application of
the load.
In the accompanying drawing we have shown our improvements applied to a
weighing-machine of the kind described in the Specification of our said former
,application, designed to be suspended from a crane-chain.

page_text: Figure is a front elevation, and Figure 2 a side elevation of the said
weighing-machine.
a is the vessel or box in which the liquid is enclosed. is the pressure-gauge in
communication with the said vessel or box. is the upper loop whereby the
machine is to be suspended 'from a crane-chain. d is the rod for transmitting to the
diaphragm which forms the top of the vessel or box a, the pressure exerted
by the load to be weighed. Upon this rod is supported a cross-bar e firmly
connected with two side rods f, each of which works in guides 9, g'. The lower
ends of the rods are firmly secured in a frame which consists of an upper
cross-bar h, a lower cross-bar provided with a hook k or a ring or the like for
supporting the load, and two sleeves or distance-pieces arranged between the said
cross-bars h, j. A screw-stud mn is firmly secured to the underside of the vessel or
box a, and extends through a hole in the cross-bar . And a screw-threaded
support or nut is fitted upon the said screw-stud below the said cross-bar h.
The rods are provided with collars which bear against the upper surface of the
cross-bar h.
f
When a load is suspended from the hook k, it will act, through the medium
of the side rods and cross-bar e, upon the rod d, and will thus exert pressure upon
the liquid in the box a; this pressure will be transmitted to the gauge and the
latter thereby caused to indicate the weight of the load.
To prevent injury to the machine by any excessive shock or jerk that may
be caused by the sudden lifting of the load by the crane, the nut n is so adjusted
that, when the rods are pulled down a short distance further than is necessary to
cause the gauge to indicate the weight of the load, the cross-bar h will rest upon
the said nut n, and any extra stress which would otherwise be put upon the
diaphragm and transmitted to the gauge, is applied through the said nut to the
screw-stud m, and communicated through this stud and through the box a to
the upper loop c. The weighing-mechanism has, therefore, to withstand only the
pressure required to indicate the weight of the load, or a slightly greater pressure,
according to adjustment of the nut. n. A locking-nut p is provided for fastening
the nut n in any position to which it may be adjusted.
By screwing up the nut a sufficient distance upon the stud m, the weight of the
load suspended from the hook & may also be removed from the weighing-mechanism
if desired. Or the load may be lifted while the nut is in position to sustain the
weight thereof, and the said nut be then turned down to allow the weight to act
gradually upon the weighing-mechanism.
In cases where it is desired simply to protect the weighing-mechanism against
injury by stresses greater than that due to the weight of the maximum load
for which the machine is constructed, we can substitute for the aforesaid adjustable
aut, a collar or other suitable support fixed upon the stud m at the required
distance below the cross-bar h.
The construction and arrangement of our improved apparatus will necessarily' be
somewhat varied according to the kind or class of weighing-machine to which our
improvements are applied. In the case of a weigh-bridge, for instance, we find it
advantageous to provide the platform which receives the load, with two or more
vertical guide-pins, and to employ interchangeable slotted washers or 'cottar-
washers of different thicknesses, which can be fitted and secured in place upon the
said guide-pins so as to serve as supports for the said platform. The stress
to which the weighing-mechanism is to be subjected is varied, in this case,
by removing the washers and replacing them with washers of greater or less
thickness as required. Or we make the said guide-pius with screw-threaded
portions on which are fitted adjustable supports or nuts adapted to sustain the
weight of the load when the said platforin has been moved downward thereby
through the required distance to record the weight of the load on the pressure-
gauge. Or we provide other suitable means for varying or regulating the stress to
which the weighing-mechanism can be subjected.
It is obvious that we can, if desired, use in place of the adjustable "nut 'n, 'in

page_text: the apparatus shewn in the drawing, interchangeable cottar-washers or other
suitable supports.
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. The herein described method of providing for the protection of a
weighing-machine against injury due to the too sudden application of a load, by the
employment of one or more adjustable or interchangeable supports adapted to resist
or sustain any excessive force exerted by the load, whilst permitting the weight of
the said load to act upon the weighing-mechanism.
Second. A weighing-machine provided with one or more adjustable screw-
threaded supports or nuts adapted to resist or sustain any excessive force due to
the too sudden application of the load, substantially as, and for the purpose, above
specified.
Third. A hydrostatic weighing-machine provided with suitable means whereby,
when the gauge has been actuated to indicate the weight of the maximum or
other predetermined load, such load will be supported independently of the
weighing-mechanism, substantially as herein before described and for the purpose
specified.
Fourth. The improved hydrostatic weighing-machine constructed with the
adjustable screw-threaded support or nut substantially as described with reference
to the accompanying drawing and operating as, and for the purposes, above
specified.
T
1
JOHN JACKSON.
EDWIN A. HOAD.
D. Young & Co.,
11 & 12, Southampton Buildings, London, W.C.,
Agents for the Applicants.