Improvements in Weighing Machines.
Year: 1889

page_text: Date of Application, 26th Feb., 1889
Complete Specification Left, 26th Nov., 1889-Accepted, 4th Jan., 1850
PROVISIONAL SPECIFICATION.
Improvements in Weighing Machines.
I, JOHN DAVIES, of 56, Leadenhall Street, in the City of London, Weighing
Machine Maker, do hereby declare the nature of this invention to be as
follows:-
My invention relates to weigh-bridges, platform weighing machines, and the like,
and has for its chief object to reduce the wear of the knife edges and bearings which
takes place in consequence of the constant raising and lowering of the platform in
putting a machine in and out of gear, whereby greater accuracy of weight than
heretofore is ensured and whereby the life of a machine is considerably lengthened.
According to my said invention, the bars or guides from which the platform is
suspended or the blocks upon which it is supported are adapted to work in vertical
guides so that the knife edges always make contact with their bearing at the same
points whereby cutting or grinding is avoided. The platform is provided with two or
more conical pins which enter corresponding openings in the frame, so that as
the said platform is lowered it will always occupy exactly the same position on
the frame.
In
The said girders or blocks may be raised or lowered by any desirable means.
practice I find it advantageous to employ toggle levers which are connected at one
end with a sliding frame, and which at the other ends engage with the bars or girders.
By moving the sliding frame it will be understood that the toggle levers assume a
more or less vertical position and thus act upon the girders or bars. I also advan-
tageously employ a series of wedges. The sliding frame or the wedges can be moved
by a rack and pinion or by any other suitable means. Springs can be conveniently
arranged to assist the motion of the said sliding frame or wedges.
I sometimes attach conical pins to the bar of the weighing beam carrying the
knife edges to prevent the said edges from cutting their bearing, as hereinbefore
referred to. I also in some cases provide the weigh beam with an additional weight
for effecting the adjustment of the beam.
Duted the 96th day of February 1889
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Weighing Machines.
1, JOHN DAVIES, of 56, Leadenhall Street, in the city of London, Weighing
Machine Maker, 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 :-
My invention relates to weigh-bridges, platform weighing machines and the like
and has for its chief object to reduce the wear of the knife edges and bearings which
takes place in consequence of the constant raising and lowering of the platform in
putting a machine in and out of gear, whereby greater accuracy of weight than
heretofore is ensured and the life of a machine considerably lengthened, and the
invention mainly consists in so constructing the machine that the points of suspension or
fulcrums of the weighing levers are adapted to be moved to raise or lower the platform.
In the accompanying drawing,
Figure 1 is a sectional side elevation of a platform weighing machine constructed.
according to my invention, and

page_text: Figure 2 is a sectional plan of the same with the platform removed, the section
being taken on the line w, w Figure 1.
Figure 3 is a sectional front elevation of the machine, the section being taken on
the line x, x, Figure 1.
and
Figure 4 is a section on the line y, y, figure 3, drawn to an enlarged scale,
Figure 5 is a section on the line z, z Figure 4.
Figure 6 is a sectional view of a modification of some of the parts.
Similar reference letters indicate similar parts throughout the drawing.
b
a is the base of the machine, a¹ the pillar, 6 the platform, c, d the usual levers
which are fulcrummed to the bars e, e and which support the platform 6 through the
medium of the frame f, and g the rod which connects the lever c with the weighing
beam or graduated arm h. All the foregoing parts are of known construction.
I will now describe my improvements. I provide the ends of the bars e, e with
slides e' which work in guides or grooves a² in the base a of the machine, in order
that the platform may be raised and lowered or put inte or out of gear without relative
movement of the knife edges in the levers c, d and bars e, e and the surfaces against
which they bear, thereby avoiding any cutting and grinding of the said knife edges
and bearing surfaces.
It will be obvious that where blocks are used to serve as the fulcrums of the
levers C,
d they can be provided with slides in a similar or equivalent manner to
the bars e, e.
1
To effect the raising or lowering of the bars e, e or blocks I joint thereto toggle
levers i provided with friction rollers, which roll upon the internal flange a³ of
the base a.
The toggle levers are all jointed at their lower ends to a rectangular
frame j, which is connected by a link j₁ to one end of a hand lever k fulcrummed
at ¹ on the base a, so that, if the lever & be operated, the frame j will cause the toggle
levers i to move in unison and raise or lower the bars e, e and consequently the
platform b. In Figure 1 the platform is shewn in its lowered position, but, if the
lever k be moved into the position shewn by the dotted lines, it will cause the toggle
levers to move into a vertical position and thereby raise the platform. Notches are
provided at the back and front of the cap of the pillar a¹ with which notches the
leverk engages, the said lever being sufficiently elastic to enable it in its movement
to be slightly bent or sprung so as to pass the side of the cap of the pillar a¹.
Instead of the toggle levers it will be obvious that I can also use wedges for the
same purpose; the said wedges are advantageously fitted or formed on the frame;
as illustrated in Figure 6 at e those for operating the platform b working hetween
rollers on the bottom of the slides e¹ and rollers at on the base a. The other
wedge for operating the bracket n works in a similar manner between rollers on the
bottom of the bracket n and on the base a.
Further instead of the hand lever k, a rack and pinion can be used. m, m are
springs one end of each of which is attached to one of the side walls of the base a
while the other end is attached to the frame j, the said springs serving to assist the
operator when lifting the platform.
To prevent any cutting or grinding of the knife edges ¹ of the weighing beam h;
when the platform is raised or lowered, I sometimes arrange that the bearings of
the said knife edges shall have a movement imparted to them corresponding to the
movement imparted to the bars e, e. To effect this, I arrange the bracket n which
projects beneath the weighing beam to slide in grooves o, o in the pillar a¹ and I
form the bearings thereon. To the lower end of the bracket n I joint one end of a
toggle lever p similar to the toggle levers i, the other end being jointed to an
extension of the frame j. By this arrangement, when the hand lever k is operated
to raise or lower the platform 6 the bracket n will also be moved a corresponding
distance.
When the bracket n is in its lowered position I arrange the weighing beam / so
that it is supported on projections q, 9 on the inside of the pillar a', it being provided
for that purpose with conical pins q', q₁ which enter similarly shaped holes in the said

page_text: projections 9, 9. By this arrangement I avoid the cutting or grinding of the knife
edges on their bearings which sometimes takes place by the accidental or other
movement of the beam h when the machine is out of gear.
In some cases I provide the rear end of the weighing beam h with an additional
weight capable of adjustment in a vertical direction by means of a screw which
screws into a lug on the said beam h, a nut being provided to lock it in position.
By this arrangement, I can alter the centre of gravity of the beam h so as to adjust
its balance.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what 1
claim is :-
(1.) A weigh-bridge or platform weighing machine in which the points of
suspension or fulcrums of the weighing levers and weighing beams are adapted to
be inoved in order to raise or lower the platform substantially as and for the purpose
herein before described.
•
(2.) Providing the bars from which the platforms of weigh-bridges and platform
weighing machines are suspended, or the blocks upon which they are supported,
with slides adapted to move in guides or grooves in the base of the machine, suitable
means such as those described being employed for raising and lowering the said bars,
substantially as hereinbefore described with reference to the accompanying drawing
and for the purpose set forth.
(3.) Providing the weighing beams of weigh-bridges and platform weighing
machines with conical pins which enter similarly shaped holes in the pillar substantially
as hereinbefore described with reference to the accompanying drawing and for the
purpose set forth.
(4.) The improved weighing-machine hereinbefore described and illustrated in the
accompanying drawing.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.