Improvements in or relating to Springs or Spring Devices applicable for Counterbalancing Window Sashes and for other purposes.
Year: 1895

page_text: Date of Application, 18th June, 1895
Complete Specification Left, 20th Apr., 1896-Accepted, 13th June, 1896
PROVISIONAL SPECIFICATION.
Improvements in or relating to Springs or Spring Devices
applicable for Counterbalancing Window Sashes and for
other purposes.
1, WATKIN HALL, of Croft Cottage, College Road, Great Crosby, in the
County of Lancaster, Civil Engineer, do hereby declare the nature of this
invention to be as follows :—
It is well known that in counterbalancing window sashes or other articles, the
use of spiral springs has the disadvantage that their resistance to compression or
expansion is variable, and the result is that it is generally far more convenient to
use weights whose pull on the window is constant rather than a spring whose
resistance is variable.
Now by my invention I overcome the variation in the resistance to compression
or expansion of the springs, and my arrangement enables me to absolutely counter-
balance a window sash or other article in all positions, which it has not been
possible to do hitherto.
In carrying my invention into effect, I will describe one arrangement as applied
to counterbalancing a window sash. Supposing the sash to be supported on an
endless chain passing round two rotatable chain wheels, I fix to the axis of a wheel
gearing into the chain wheel two eccentrics, to the periphery of one of which is
attached the end of a line leading over a pulley to a spring to which the line is
coupled, these eccentrics being so arranged that one of them acts with an increasing
leverage, while the other acts with a decreasing one and vice versa. To the
periphery of the other eccentric is attached a similar line leading in an opposite
direction over a pulley to another spring, to which spring the end of the line is
coupled. These springs may be enclosed in cases for protection. It will be seen
that by providing these two springs and eccentrics it ensures the sash being in
absolutely stable equilibrium in all positions, as when the sash is lowered one of
the springs will be elongated by the eccentric pulling on the line, but with a
gradually decreasing leverage, while the other spring will also be elongated but
will gather strength by the other eccentric pulling on the other line with a
gradually increasing leverage and so maintains the exact power required without
variation. Thus if one spring at the beginning of lowering the window commenced
with 50 lbs. and the other spring with 10 lbs. to sustain the 60 lbs. weight of the
window, then when the sash had been completely lowered to the bottom, the first
mentioned spring would only exert some 10 lbs., while the other spring would have
taken up the 50 lbs.
I have described one way of carrying my invention into effect, but it is obvious
that having once given the general idea, the details of the invention may be con-
siderably varied without departing from the nature of the invention: thus, for
example, instead of using two eccentrics, one eccentric might be used to overcome
the variation where sufficient space existed, but in practice for my special purpose
owing to a very limited space wherein to place the gear, I find two smaller
eccentrics give on the whole a better result. I have set forth my invention as
applied to counterbalancing window sashes, but it must be distinctly understood

page_text: that I do not limit myself thereto as the invention can be used for a variety of
other purposes beside.
Dated this 17th day of June 1895.
WM. P. THOMPSON & Co.,
Of 6 Lord Street, Liverpool, Patent Agents for the Applicant.
.
Improvements in or relating to Springs or Spring Devices
applicable for Counterbalancing Window Sashes and for
other purposes.
I, WATKIN HALL, of Croft Cottage, College Road, Great Crosby, in the
County of Lancaster, Civil Engineer, 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 :--
It is well known that in counterbalancing window sashes or other articles, the
use of spiral springs has the disadvantage that their resistance to compression or
expansion is variable, and the result is that it is generally far more convenient to
use weights whose pull on the window is constant, rather than a spring whose
resistance is variable.
Now by my invention I overcome the variation in the resistance to compression
or expansion of the springs, and my arrangement enables me to absolutely counter-
balance a window sash or other article in all positions, which it has not been
possible to do hitherto.
The invention will be understood from the following description, reference being
had to the accompanying drawings, which show my invention applied to
counterbalancing a window sash, in which,
Figure 1 is a front view of my invention;
Figure 2 a slightly modified arrangement;
Figure 3 a view showing the arrangement for adjusting the eccentric on its
axis; and
Figure 4 a front view showing my invention with two eccentrics and springs
applied instead of one.
A is a frame such as a sash requiring to be raised and lowered, said sash being
supported by means of a bracket A on an endless chain B passing round two
rotatable sprocket wheels C C, and operated through suitable interposed gearing
by means of a handle thereby raising and lowering the sash as will be understood
by reference to my prior Patent No. 2131 of 1894. I fix on the axis of the
circular rack D, which gears into a pinion c on the sprocket wheel C, an
eccentric E, to the periphery of which is attached the end of a line E' leading
over a pulley e to a spiral spring G to which the line is coupled, the opposite end
of the spring being fastened to a fixed point at g. The result of this construction
is that the tendency of the spring is to counterbalance the weight of the window
sash, as when the sash is lowered the spring will be elongated, by the eccentric E
pulling on the line E¹ but its resistance to elongation will increase in proportion as
the leverage of the eccentric decreases. The leverage upon the counterbalancing
spring will therefore in lowering the window be reduced in proportion as the force
of the spring increases, while in raising the window, the opposite effect will take
place, so that the pressure of the spring in counterbalancing the window sash will
be uniform in all positions.
The mode of action is as follows:-
To lower the sash, the handle which is attached to the circular rack D is turned
in the direction of the arrow, and by means of the gearing Dc and C causes the
chain B to travel, thereby lowering the sash, which, as already stated, is supported

page_text: on the chain, the spring G, counteracting the weight of the sash in its descent.
As, however, the resistance of the counterbalancing spring G to elongation
increases, the leverage of the eccentric upon it will be reduced, and thus the
tension of the spring in counterbalancing a window will be practically uniform.
The leverage of the eccentric may be adjusted on the axis of the circular rack D
by means of the arrangement set forth in Figure 3, in which E is the eccentric,
D' the boss of the circular rack D, H an elongated opening in the eccentric
receiving the boss D¹, I, small slots for the binding screws J, K a pin mounted at
one end in the eccentric so as to freely rotate therein, but prevented from sliding
longitudinally by a pin L engaging in a groove in the pin K.
At the other end
this pin is screwed into the boss D', so that by rotating the tommy head of the
pin, first slackening the binding screws J, the eccentric will be adjusted in relation
to the axis and fixed in that position by tightening up the binding screws
aforesaid.
In Figure 2 an eccentric is again shown fixed to the axis of the circular rack D
and a spiral spring G fixed at any convenient point and operated by means of a
line or chain E¹, one end of which is attached to the eccentric E and the other end
to the spring G, while the end of the casing confining the spring is pivoted at g.
The result of this construction is that the tendency of the spring will be to counter-
balance the sash, as in lowering the sash, the spring will be compressed and its
resistance to compression will increase in proportion as the leverage of the eccentric
diminishes, while in raising the window the opposite effect will take place. The
resistance of the spring will, therefore, increase as the leverage upon it is reduced,
so that the pressure of the spring in counterbalancing the window will be
approximately uniform.
It will be obvious that instead of one eccentric, two eccentrics may be used to
overcome the variation, and these in some cases, give an even better result than
one eccentric. The arrangement of two eccentrics is shown by way of example in
Figure 4, in which D is the circular rack as before, E and F the two eccentrics, to
the periphery of one of which is attached the end of a line E' leading over a
pulley e to a spiral spring G to which the line is coupled, the other end of the
spring being secured to a fixed point. To the periphery of the other eccentric is
attached a line F¹ leading in the opposite direction over a pulley f to the spring GI
to which the end of the line F¹ is coupled, the other end of the said spring being
secured to a fixed point same as G. These springs may be enclosed in a cylindrical
box for protection if so desired. It will be seen that by providing these two
springs and eccentrics they ensure the sash being in absolutely stable equilibrium
in all positions. Both springs have a tendency to counterbalance the weight of
the sash, as when the sash is lowered, both springs will be elongated, the spring G
by the eccentric E pulling on the line E', but with a gradually decreasing leverage
and the spring G¹ by the eccentric F pulling on the line F but with a gradually
increasing leverage. The springs G will therefore both gather strength or force
but in an unequal proportion, as when the sash is lowered the spring G will be
elongated by the eccentric E pulling on the line E', but its resistance to elongation
will increase in proportion as the leverage of the eccentric decreases while the
spring G will be elongated by the eccentric F pulling on the line F¹ and its
resistance to elongation will increase in proportion as the leverage of the eccentric
increases. Thus by way of illustration, if the spring G, owing to the leverage of
the eccentric E, exerts 50 lbs. and the spring G¹, owing to the smaller leverage of
the eccentric F, exerts 10 lbs. to counterbalance the 60 lbs. weight of the sash
when raised, then G, when the sash has been lowered down to the bottom, will
exert only some 10 lbs. due to the decreased leverage of the eccentric E, while G
will exert 50 lbs. due to the increased leverage of its eccentric F. The great
advantage of using the two springs instead of one is that it enables me to use
smaller springs which take up considerably less space than if one spring equal in
force to the combined power of the two smaller springs be used. I have described
the above ways of carrying my invention into effect, but it is obvious that having

page_text: once given the general idea the details of the invention may be considerably varied
without departing from the principle of the invention. I have set forth my
invention as applied to counterbalancing the window sashes, but it must be under-
stood that I do not confine myself thereto, as the invention may be used in
· connection with other articles requiring to be raised or lowered.
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 I
claim is :-
1. The improvement in apparatus applicable for counterbalancing by means of
springs, the weight of window sashes and other articles requiring to be raised or
lowered substantially as described, whereby the force of the springs in
counterbalancing the sash or other article is rendered practically uniform.
2. In a device for raising or lowering a window sash or other article requiring
to be raised or lowered, a counterbalancing spring or springs arranged in combina-
tion with an eccentric or eccentrics or their equivalents in such a manner, that as
the force of the springs increase, the leverage thereon will be reduced and thus the
pressure of the springs in counterbalancing the sash or other article is rendered
practically uniform, substantially as described.
3. In a device for raising or lowering a window sash or other article requiring to
be raised or lowered, counterbalancing springs each arranged in combination with
an eccentric in such manner, that as the force of the springs increase the leverage
on one of the eccentrics will be reduced while the leverage on the other will be
increased in approximately corresponding proportion, whereby the pressure of the
springs in counterbalancing the sash or other article is rendered practically uniform,
substantially as described.
4. In a window sash the arrangement for counterbalancing the weight of the
window, which consists in providing in combination with a sprocket wheel C a
toothed segment D geared thereto, and a counterbalancing spring or springs
coupled to the segment by means of an eccentric or eccentrics in such manner that
the pressure of the springs in counterbalancing the sash is practically uniform,
-substantially as set forth.
5. In a device for raising or lowering a window sash or other article requiring
to be raised or lowered, the combination therewith of counterbalancing springs
arranged in conjunction with the eccentrics or their equivalent in such manner,
that the pressure of the spring in counterbalancing the sash is practically uniform,
and means for adjusting the throw of the eccentrics to obtain the required leverage
on the springs substantially as described.
6. The combination and arrangement of parts substantially as and for the
purpose herein before described and shown in Fig. 1, Fig. 2, and Fig. 4 of the
accompanying drawings in so far as they differ from my former invention set forth
in my Patent aforesaid.
LOBA
of April 1998.
WM. P. THOMPSON & Co.,
Of Liverpool, Manchester, Birmingham, and London, Patent Agents.