Improvements in Weighing Scales and Balances.
Year: 1893

page_text: Date of Application, 22nd June, 1893
Complete Specification Left, 25th Oct., 1893-Accepted, 23rd Dec., 193
PROVISIONAL SPECIFICATION.
Improvements in Weighing Scales and Balances.
I, CHARLES HENRY BARTLETT of Branscombe, Woodstock Road, Bristol, in
the County of Gloucester, Scale Maker, do hereby declare the nature of this
invention to be as follows:
This invention relates to improvements in the construction of weighing scales
and balances, and has for its principal object to so construct the beam as to obtain
increased sensibility and precision conjointly with the necessary strength and
durability. It has alsc for its object to facilitate the fixing of the centres in
rigorously-accurate relative position so as to render the fixing and renewal of parts,
upon which the accuracy and sensibility of the balance so largely depends,
independent of skilled labor. It also relates to the means of fixing the agate
bearings in their holders, and to other details of construction as hereafter
described.
In order to increase the sensibility of the scale or balance, the beam is made
tubular, preferably of solid drawn steel tube of round or oval section, the latter
being best adapted to combine lightness with inflexibility.
In order to stiffen the beam and compensate for loss of strength due to the
mode of fitting the middle centre knife edge as hereafter described, the beam is
trussed by tension wires extending from an upwardly projecting central strap or
clip affixed to the beam and passing through abutments in the ends of the beam,
with nut and screw adjustments for applying the tension. For light weights
however, this trussing is not required, the beam being strong enough without it.
The improved mode of fixing the knife edge centres is applicable both to tubular
and to solid beams, and consists in cross-notching the beam at the upper side for
the middle centre and at the lower side for the end centres, with V-shaped notches
forming seats for the knife edge bars which are secured therein as hereafter
described. This cross-notching may be conveniently performed by means of a
milling tool to a depth regulated by a gauge, so that little or no skill is required
in adjusting the centres exactly equidistant and in true line with the centre of
gravity, thus reducing to a minimum the final adjustment necessary to attain the
maximum of sensibility compatible with stability of the balance, the form of the
notch being such that the knife edge bar must bed firmly therein when secured
as next described. The middle centre bar is secured by a pressure screw passed
through a nut contained within the bow of the central strap or clip above referred
to and bearing directly upon the back of the knife edge bar, the thrust of the
screw being resisted by the attachment of the strap or clip to the beam and in
some cases by the tension wires also by which the beam is trussed, as above
mentioned.
A convenient way of attaching the clip to the beam is by rivetting together.
the two ends of the clip or strap drawing it up tight against the beam and
rivetting through clip and beam. The knife edge bars for the end centres may be
similarly secured in their notches by clips or straps embracing the beam and by
pressure screws and nuts as above described for the middle centre or in the case
of a tubular beam they may be secured by wedges driven endwise into the beam
so as to lie across the notches and bear against the back sides of the knife edge
bars. In either case the knife edges are easily and securely fixed in their proper
positions, with a degree of accuracy not attainable by the most skilled labor when,

page_text: they are driven through the beam in the ordinary way and all danger of
impairing their accuracy by upsetting under the blows of the hammer is obviated.
The improvement in the construction of the shackles or holders for the agate
bearings of the knife edge centres consists in stamping out blanks of suitable
shape from sheet metal and stamping them up to form box-like holders open on
their inner sides for the reception of the agate blocks. Each blank has two side
wings which are first turned up at right angles to the plane of the blank so as to
stand parallel and form the opposite sides of the box, the extremities of these sides
being then bent inwards towards each other to form the end of the box. The
two boxes thus formed are rigidly connected together by a cross-bar to complete
the shackle. The end of the box extends beyond the middle portion or back so
that an abutment is formed for an offset or shouldered portion at the back or
outer side of the agate block whereby the correct position of the agate is deter-
mined, fixity being ensured by a half round tapered cross key driven through
holes punched in the sides of the box and bearing with its flat side against the
opposite face of the agate or by a dovetailed key in corresponding seats.
bearing boxes of the middle centre are rivetted or otherwise fixed in a U-shaped
or other suitable bracket carried by the centre pillar, whilst to the end shackles
are pivoted swivel connections for scale-pan suspension links. The usual vertical
pointer is replaced by a horizontal one projecting from the face of the beam in
combination with a laterally projecting horizontal fixed pointer carried by the
middle centre supporting or suspending bracket.
The
In order to make the scale pans pack away into a small compass without the
use of chains, the suspension rod for the goods scale-pan is hinge-jointed so that
it may fold down across the scale pan whilst the weight scale pan is pivoted to a
-shaped spring yoke whose ends are inwardly turned and received in ears at the
underside of the scale pan whilst the side members of the yoke spring into notches
in the edges of the scale pan whereby to rigidly yet jointedly connect the pan and
yoke. These ears are preferably formed on the casing or box rivetted to the
underside of the scale pan and containing the shot or other weights by which the
initial adjustment of the balance is effected.
The improvements in the construction of the beam, centres, and bearings, above
described are applicable not only to suspended or standard scales, but, with suit-
able modifications, to counter balances of the Beranger or Roberval type.
Dated this 22nd day of June 1893.
C. H. BARTLETT,
By A. M. & Wm. Clark,
53, Chancery Lane, London, Chartered Patent Agents.
COMPLETE SPECIFICATION.
Improvements in Weighing Scales and Balances.
I, CHARLES HENRY BARTLETT of Branscombe, Woodstock Road, Bristol, in
the County of Gloucester, Scale 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 :-
This invention relates to improvements in the construction of weighing scales
and balances and has for its principal object to so construct the beam as to obtain
increased sensibility and precision conjointly with the necessary strength and
durability. It has also for its object to facilitate the fixing of the centres in
rigorously, accurate relative position, so that whether in the original fixing of those
parts, or in their subsequent renewal in case of wear, the justness and sensibility
of the balance which so largely depend on accurate fitting, may be ensured
independently of skilled labor. It also relates to the means of fixing the agate
bearings in their holders, and to other details of construction as hereafter
described.

page_text: Specification, wherein
the accompanying urawings, forming part of UHIS
Figure 1 is a front elevation of the balance.
Figure 2 is a central longitudinal sectional elevation of one half of a tubular
scale beam, illustrating the preferred construction of the beam and the method of
fixing the middle and end knife edge centres.
Figure 3 is a plan thereof, the holder for the middle bearings being in section on
line 1-1 Figure 4.
Figure 4 is a central transverse section of the beam and its centre bearings.
Figure 5 is a horizontal section on line 2-2 Figure 4, the beam being removed.
Figure 6 is an end elevation of the beam with the end shackle suspended
thereon.
Figure 7 is a central trausverse vertical section of said shackle on line 3-3
Figure 8 which is a vertical section of same on line 4-4 Figure 7.
Figure 9 is a longitudinal vertical section of part of the beam shewing the notch
which receives the middle knife edge.
Figures 10 and 11 illustrate in side elevation and cross section the application of
the improved mode of fixing the knife edge centres to a solid beam.
Figures 12 and 13 are detail views of the weight scale-pan joints.
The same letters of reference correspond to the same parts in all the figures
In order to increase the sensibility of the scale or balance, the beam A is made
tubular preferably of solid drawn steel tube of round or preferably oval section, as
shewn, the latter being best adapted to combine lightness with inflexibility under
conditions of use. In order to stiffen the beam and compensate for loss of strength
due to the mode of fitting the middle knife edge centre, as hereafter described, the
beam A is trussed by tie-rods or wires B extending from an upwardly projecting
central strut formed by a strap or clip C affixed to the beam, the said ties B passing
through holes in the upper side of the beam and through abutments D at the ends
of the beam with nut and screw adjustments 6 for applying tension to the said tie-
rods which may be connected to the strut C by passing through holes therein and
terminating in hooked ends with heads b' as shewn. The abutments D are end
plates bearing against the ends of the beam A which are cut to a bevel so as to
bring the abutments perpendicular to the tie-rods B. The strip or clip C which
forms the post of the truss is a plate bent to the form shewn in Figures 4 and 6,
its two ends being rivetted together as at c and the clip, when slipped over
and drawn tight against the underside of the beam, rivetted thereto by cross-
rivets c¹.
Although I have described and intend to claim the mode of trussing the beam
the invention is not limited in this respect, inasmuch as for light weights the
trussing may not be requisite the tubular beam being strong enough without it.
The improved mode of fixing the knife-edge centres which I will now describe,
is applicable both to tubular and to solid beams and consists in cross-notching or
slotting the beam at the upper side for the middle centre E (as shewn in Figure 9)
and at the lower side for the end centres F with V-shaped notches e, f, respectively
corresponding in form to, and forming seats for, the knife-edge bars E, F, which
are secured therein by pressure applied directly to the backs of the knife edge
bars as hereafter described. This cross-notching may be conveniently performed
by means of a milling tool to a depth regulated by a gauge so that little or no skill
is required in adjusting the centres exactly equidistant and in true line with the
centre of gravity of the beam thus reducing to a minimum the final adjustment
necessary to attain the maximum of sensibility compatible with stability of the
balance.
The form of the notches e, f, is shewn in Figure 9 and is such that the bevelled
faces of the knife edge bars E, F, must bed firmly upon the correspondingly inclined
bottoms of the notches when secured as next described.
The middle centre bar E is secured by a pressure screw G passed through a nut
or filling piece g contained within the bow of the central strap C above referred to,

page_text: the screw G bearing directly upon the back of the knife edge bar E and its thrust
being resisted by the attachment of the strap C to the beam A and also by the tie
rods B if, as would generally be the case, the beam is trussed as above described.
The knife edge bars for the end centres may be similarly secured in their notches
by clips or straps embracing and rivetted to the beam in the same way as clip C and
by pressure screws as above described for the middle centre, the position of the
parts being of course such that the pressure is applied in the upward direction to
suit the inverted position of the knife edges F.
In the case of a tubular beam A, such as shewn in Figures 1 to 9, the knife
edges F may be secured by wedges H driven longitudinally into the beam so as to
lie across the notches f and bear against the under sides of the knife edge
bars F. These wedges are very slightly tapered and are accurately fitted and
driven.
In Figures 10 and 11 I have shewn this mode of fixing the knife edge bars as
applied to a solid beam.
In either case the beam A is V-notched as before described and the clip C¹ is a
strap straddling the beam and provided with apertures c through which the knife
edge bar E or F passes, the strap C¹ in this case being loose on the beam and taking a
bearing against the back of the knife edge bar at either side of the beam and being
caused to draw the knife edge to its seat in the V-notch e by a wedge H driven
between the bow of the strap and the edge of the beam or by a pressure screw,
screwing through a hole tapped in the bow of the strap and bearing upon the edge
of the beam.
By this improved mode of fixing the knife edges they are easily secured in their
proper positions with a degree of accuracy not attainable by the most skilled
labor when the knife edges are driven through the beam in the ordinary way and all
danger of impairing their accuracy by upsetting the metal under the blows of the
hammer is obviated.
2
The improvement in the construction of the shackles or holders I for the agate
bearings J of the knife edge centres F consists in stamping out blanks of suitable
shape from sheet metal (preferably sheet steel) and stamping or blocking them up to
form box-like holders open on their inner sides. Each blank has two side wings which
are bent at right angles to the plane of the blank so as to form the opposite side
cheeks of the box, the middle portion of the blank forming the back of the box
whilst the extremities of the cheeks are bent inwards towards each other as at 12 to
form the upper end of the box, these operations being effected by suitable forming
blocks and dies of hardened steel. The two boxes thus formed are rigidly connected
together by a cross-bar ³ and to complete the shackle a swivel connection is
pivoted thereto as shewn for the connection of the scale pan suspension links. The
upper end of each box projects beyond the back t' so that an abutment is provided
for an offset or shoulder formed at the back or outer side of the agate block J
whereby the correct height of the agate in its box is determined, fixity of position
being ensured by a tapered cross-key k driven through the side cheeks i of the box
and bearing against the inner face of the agate. The two boxes constituting the
shackle, when made of steel need no steel liners for the end points of the knife edge
centre to bear against (as when the shackle is made of cast brass) and being stamped
out and blocked up by the same or precisely similar dies they enable the agate
blocks to be more truly bedded, more easily and perfectly aligned, and more easily
replaced if broken or otherwise damaged, than is possible when the blocks are fixed
by cement in cored out cast metal boxes as usual heretofore. The keys k shewn in
Figures 6. 7, and 8, are dovetailed and received in corresponding seats in the side
cheeks i, but the form of key shewn in Figure 4 is preferred. This is a tapered pin
of half-round section driven through complete circular holes in the side cheeks i, so
that the taper of the pin tightens it against the agate whilst the circular form allows
the flat side of the pin to adjust itself to the face of the agate. The bearing boxes 1
of the middle centre are similarly made and the agate blocks J are secured therein
as last described, the boxes, instead of being connected by a cross-bar, being

page_text: rivetted or otherwise fixed in a U-shaped or other suitable bracket L carried by the
centre pillar M or otherwise. In order to shorten the suspension tackle, the usual
vertical pointer is replaced by a horizontal one N projecting from the face of the beam
and used in combination with a laterally-projecting horizontal arm O carried by the
bracket L, as shewn in Figures 1 and 3. In order to make the scale pans pack
away into a small compass, without the use of chains, the suspension rod for the
goods scale pan P is hinge-jointed at p, so that it and the scale pan may be folded
across one another as shewn in dotted lines in Figure 1, whilst the weight scale
pan R is pivoted to a spring yoke S whose ends & are bent inwardly beneath the
scale pan and received in ears t at the underside of the scale-pan, in which ears the
ends are free to slide, whilst the side members of the yoke tend to spring inwards
and engage in V-shaped notches in the edge of the scale-pan, so as to oppose the
pivotal action and hold the pan rigidly at right-angles to the yoke and yet admit
of the pan being forcibly turned on the ends s as pivots, the act of turning the pan
forcing the limbs of the yoke to spring out of the notches. The earst are shewn
as being rivetted to the pan R, but they, as also the V-shaped notches r, would
preferably be formed on the casing or box T, rivetted or screwed to the underside of
the scale pan and containing the shot or other weights by which the initial
adjustment of the balance is effected.
The improvements in the construction of the beam, centres, and bearings above
described are applicable not only to suspended or standard scales but, with suitable
modifications, to counter balances of the Beranger or Roberval type.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is-
1. The construction of a scale beam of a metal tube trussed by tie-rods, substan-
tially as specified.
2. The herein described mode of fixing the knife edge centres in a scale beam
whether solid or tubular, which consists in cross-notching or slotting the beam to
form a seat for the knife edge bar and holding the latter thereto by pressure applied
directly to the back of the knife edge bar, substantially as specified.
3. The herein described mode of fixing the end knife edge centres in a tubular
scale beam by cross-notching or slotting the beam as described and driving a wedge
into the beam so as to bear against the back of the knife edge bar and press the
latter into its seat, substantially as specified.
4. The herein described mode of fixing the knife edge centres in a solid beam,
which consists in cross-notching or slotting the beam, as described, and pressing the
knife edge bar to its seat by a wedge or screw applied to act on an apertured clip
or strap straddling the beam and engaging with the back of the knife edge bar as
described.
5. The herein described mode of constructing the shackles or holders for the
agate bearing blocks, which consists in stamping out blanks for each box from sheet
metal, bending up the side wings of the blanks at right angles to form the side
cheeks of the boxes, and bending inwards the ends of the wings to form the end of the
box, substantially as specified.
6. The herein described means of fixing the agate bearings in their boxes, which
consists of a shoulder at the back of the block engaging with the back of the box in
combination with a tapered cross-pin driven through the side cheeks of the box, as
described.
7. The combination, with the agate block, of a half-round tapered cross-pin driven
through holes in the side cheeks of the block and bearing against the agate block,
as described.
8. An index for a scale, consisting of a pointer standing out from the face of
the beam in combination with a laterally-projecting fixed horizontal arm, as
described.
9. The mode of pivotally yet rigidly connecting the weight scale pan to a

page_text: -shaped spring yoke by the pivotal ends of the yoke being received in ears whilst
the side members of the yoke spring into V-notches, as described.
Dated this 25th day of October 1893.
C. 11. BARTLETT,
By A. M. & Wm. Clark,
53, Chancery Lane, London, Chartered Patent Agents.