An Improved Window Sash and Blind Balance.
Year: 1899

page_text: Date of Application, 27th Mar., 1899-Accepted, 6th May, 1899
An Improved Window Sash and Blind Balance.
A communication from THOMAS ANDREW, of Sydney, in the Colony of New
South Wales, Mechanical Engineer.
İ, ALFRED JULIUS BOULT, of 111, Hatton Garden, in the County of London,
Chartered Patent Agent, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement:-
Windows that are constructed with lifting sashes are usually provided with
cords which pass over pulleys at the sides of the frame. At the opposite extre-
mities of the cords, are weights which serve to counterbalance the weight of
the sash, so that, when the sash is lifted, it shall remain in any position it may
be in when the lifting power is removed. This mode of balancing the sash is
subject to many disadvantages, not the least of which, is the annoyance and in-
convenience that results from the breaking of the sash line.
The present invention has been specially designed for the purpose of minimis-
ing these disadvantages.
Above the window is a box which may be opened from the front. In the box
are placed two horizontal fixed shafts, one for each sash. If found more con-
venient each of these shafts may be divided into two parts. Rotating loosely upon
each shaft, at each end are pulleys. Surrounding the shaft is a very long helical
spring. One end of the spring is made fast to the shaft and the other end is
made fast to the pulley. Cords or tapes are secured, at one end to one side of
the sash and at the other end to the pulley which is above.
When the sash is raised, the spring being in tension, will wind itself
on the
up
shaft and will offer sufficient resistance to retain the sash in the position in which
it is left, but will not offer sufficient resistance to prevent the sash from being
pulled down or from being put up, according to whether it is the bottom or
top sash that is being operated upon.
In the accompanying drawings:-
Figure 1 shews the arrangement of appliances arranged in a box above the
window, in this case the horizontal shafts being divided into halves.
Figure 2 is a transverse section of the same taken on the line 1-2 of
Figure 1.
A is the bottom sash; B is the top sash. C is a box above the window in
which are fixed two horizontal shafts D, D¹, and E E' such shafts being divided
at their middles by the vertical stav bearing F. It has been found much more
convenient thus to divide each shaft into two parts as it gives greater rigidity
to the apparatus. At the outer extremities of the shafts D D¹ and E E¹ are
pulleys GG, H H which are mounted loosely on their respective shafts.
Attached to the sash A at each side are cords J J which are passed upwards

page_text: round the pulleys H H¹ to which they are made fast. Similarly, the sash B is
provided with cords K K' which pass upwards round their respective pulleys G G!.
Each of the shafts is enveloped by helical springs L one extremity of such
spring being secured to the pulley while the other end of the spring is made
fast to the fixed shaft.
The springs being in tension, when a sash is lifted, the springs will wind up
on their respective shafts thus causing the pulleys to which they are attached, to
rotate and wind up the sash cords. Owing to the tension of the springs not
having been fully expended, the force of the springs will retain the sash in the
position in which it may happen to be when the lifting power is removed from
the sash. In order that the tensile power in the spring may be fairly equalized
as its power is given out, it is necessary that the springs should be of great
length,
With a view to facilitate the adjustment of springs, and the ready removal and
replacement of the shafts and rollers, these latter are mounted in the bearings
shewn at Figures 3 and 4 of the drawings. The shafts D E shewn in Figures 5
and 6 are provided with crank handles D2 E whereby they may be rotated
(when removed from their bearings) the drums G-H meanwhile being held by
the fingers to prevent them from turning. When the tension upon the springs L
is sufficient, the shafts will be inserted into the slots N, N of the bearing
plates M; the crank handles D' E will lie in the slots so that they cannot
revolve and the resilience of the springs will be maintained.
The same principle may be applied with equal facility to balancing heavy
blinds.
Having now particularly described and ascertained the nature of this said
invention as communicated to me by my foreign correspondent, and in what
manner the same is to be performed, I declare that what I claim is :
1. In combination, a window sash, a sash cord one end of which is attached to
the sash, a pulley to which the other end of the sash cord is fastened, such pulley
revolving loosely upon a fixed shaft above the sash, and a very long helical
spring, one end of which is secured to the loose pulley while the other end of the
spring is secured to the opposite end of the fixed shaft; as and for the pur-
poses herein specified.
2. The combination as specified in Claim 1, with the crank handles and slotted
bearings as shewn in Figures 3, 4, 5 and 6 for the purposes set forth.
Dated this 27th day of March 1899.
BOULT & WADE,
Agents for the Applicant.