Improvements in Spring Balances.
Year: 1887

page_text: COMPLETE DI ECIFICATION.
Improvements in Spring Balances.
We, GEORGE SALTER of the firm of George Salter and Company of West Bromwich
in the County of Stafford Manufacturer, and JOHN HUGHES of Hope Street West
Bromwich, aforesaid, Foreman of Works, 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:
-
In ordinary spring balances, the operating rack by which the pointer axis is worked,
is fixed to the cross head of the draw-bar, and it is from this draw-bar, which passes
through an opening in the lower part of the box case, that a weight to be weighed
is suspended.
This rigid connection of the rack is often detrimental to the apparatus, and especially
in the weighing of heavy weights, inasmuch as the rack is compelled to travel at all
times with the moving parts.
Our invention has for its object the remedying of these defects, by loosely con-
necting the rack, to the cross head of the draw-bar as aforesaid, which admits of the
rack having an independent motion of the bar, on the contraction or reaction of the
springs, on a weight being suddenly removed from the suspending bar, or on a chain
or other connection, breaking.
This mode of connection prevents concussion and breakage to the moving parts, as
the rack is allowed to disassociate itself from the cross-head, and so move back inde-
pendent of the parts to which the weighing springs are directly connected.
Figure 1 represents in front elevation, a spring balance, (having the dial plate
removed) provided with improvements made according to our invention; the balance
is represented with the springs and other parts in positions, which they assume when
the apparatus is in use. Figure 2 represents a like view as that of figure 1, but with
the dial plate partly broken away, and with the parts of the balance in their normal
positions, or the positions which they would assume when the balance is not in
use. Figure 3 shows a transverse vertical section of a complete balance. Figure 4

page_text: represents an enlarged view of the loosely connected rack and auxiliary parts employed
in connection therewith.
The same letters of reference indicate corresponding parts in the several figures of
the drawings.
a is the box enclosing framing of the balance, open at its front, and covered or
enclosed by a graduated dial plate b, and before the markings or graduations of which,
a pointer c traverses. d, d, are coiled or helical springs arranged parallel to each
other, and hooked at their upper ends to depending connections e2, of a fixed bracket e,
secured at the top of the inside of the case a.
i
The lower ends of these springs d, d, arc hooked or connected to a movable cross
head or carrier f, which forms the head or upper part to a draw-bar f, whose shank
passes through an opening a, made in the bottom of the balance casing. g is a loose
rack, whose lower end rests by gravity upon and seats itself within a coned recess h³
of a head 2, of a connecting link h. This link is connected to the combined cross
head and bar ff, by a fixed stud or pin upon which the said link moves; thus, if
the draw bar be suddenly released, when the springs are fully distended, as in figure 1,
then the contraction of the said springs, and the taking back of the parts connected
with them, to their normal positions as in figure 2, does not directly influence the rack's
motion in that direction; so that any shock which may thus occur, is not imparted to
the rack and pointer.
j is a fine coiled spring, encircling the lower end of the rack, and fixedly connected
at its two opposite ends, to the head of the link h, and to the fixed plate k secured
to the lower side of the pinion axis bearing block 1.
The distension of the primary springs, and the pulling down of the draw-bar, when
a weight is suspended thereto, causes the link to travel with the said bar, in con-
sequence of the pin being a fixture with it. m is a pinion, secured upon the finger
axis and which said pinion gears with the rack 9 so that on the reciprocation of
the said rack, the finger c which is upon the axis n, is made to traverse the graduations
on the dial.
o is a slotted guide, wherein the upper part of the rack reciprocates and works,
while p is a flat spring, for keeping the rack up to its bearing with the pinion, as seen
in figure 4.
The front bearing of the pinion axis, works within a bridge plate y, extending across
the middle of the open front of the balance casing.
The balance is suspended by the shank r, carrying at its top, a hook or ring.
The action of the balance, is as follows.―
On placing a weight upon a hook or other connection carried by the draw-bar f, the
primary coiled springs d are proportionally elongated, and the other parts drawn down
as illustrated in figure 1.
The change of position, or the moving down of the draw-bar, causes the pin i to
carry with it, the link h, and so distend the coiled spring j, when the rack by gravity,
or by its own weight, follows up, and falls to the extent of the motion of the said link,
and so thereby indicates, through the intervention of the pinion, pinion axis and
pointer, the weight of an article suspended.
On removing the weight from the hook carried by the draw-bar, the springs d
contract, and the parts f,f2, resume their normal positions, as represented in figures
2, 3 and 4.
The passing back of the draw-bar leaves the link free, and allows the spring j to
contract, and take back the rack to its original position before weighing as represented
in the said figures 2, 3 and 4.
Although we have represented our invention in connection with a spring balance
of the kind herein described, yet we wish it to be understood that our said invention
is applicable to all spring balances and weighing machines having rack and pinion
movements.
The top or head of the link may be coned, and the bottom of the rack similarly she
coned, instead of as represented this coning and countersinking, keeps the rack
central with respect to the link and other parts.

page_text: Having now particularly described and ascertained the nature of our said invention,
and in what manner the same is to be performed, we declare that what we claim is.-
First Preventing concussion and breakage of the moving parts of spring balances,
by disassociating, or partially disassociating the rack's motion, from that of the
motion or motions of the primary moving parts, substantially as described and
illustrated.
Secondly-A loosely working and gravitating rack, or its mechanical equivalent,
which descends, follows up the detracting or retiring parts, and works the finger axis,
on the elongation of the springs, (or a spring) when an article is weighed, substantially
as described and set forth.
Thirdly In spring balance rack mechanism, consisting of a loosely connected
rack g, encircling spring, link h, 2, and fixed pini in connection with a draw-bar
and cross-head ff, the parts being constructed, arranged and working in the manner
and for the purpose herein described and set forth.
Fourthly The combination of a loose rack g with a link has set forth.
:-
Fifthly Constructing and arranging the parts of spring balances, in the manner
hereinbefore described and illustrated in the several figures of the drawings, whereby
the rack is loosely connected, and falls by its own weight for the working of the finger,
and is returned to its normal position, by an independent spring operating in the
manner and for the purpose substantially as described and set forth.
Dated this Twentieth day of July 1887