A New or Improved Frictional Spring Clutch or Brake.
Year: 1896

page_text: Date of Application, 30th June, 1896
Complete Specification Left, 26th Mar., 1837-Accepted, 26th June, 18'7
PROVISIONAL SPECIFICATION.
A New or Improved Frictional Spring Clutch or Brake.
1 GAVIN STRUTHERS ROBB of 43 Carnarvou Street in the County of the City
of Glasgow, North Britain, Chemist do hereby declare the nature of this invention
to be as follows:-
This invention which relates to a new or improved frictional spring clutch or
brake is applicable to all cylindric bodies moving round an axis either by gravity
or other force or forces and is so designed as to come into operation when the
power (not gravitational) has been removed.
The function of my improved clutch or brake is negative, that is to say,, its
tendency as opposed to constant resistance is to save power and let it out the
moment it is opposed in the direction contrary to which that power, to which it was
passive was applied.
By virtue of its arrangement very little power is required to set the cylindric
moving body in motion, the degree of friction which held it fast when the power
was removed is so nicely adjusted as to prevent the opposing force, namely gravity,
from accumulating to such extent as to overcome it at any time.
In describing my invention I shall confine myself to only one form of its
application; namely, to a window blind roller.
It is well known that the tendency of such blinds is to run down when not
otherwise opposed. This is due to a counterweight which is usually in the form of
a rod or lath, together with the weight of the blind.
In order to resist this tendency automatically I propose to mount, in accordance
with my invention, one of the ends of the blind roller, with a metal collar or band
(having the axial stud) preferably of brass; and I take a spring after the manner,
or indeed it may be constituted a part of a clock spring, of well tempered steel
coiled in a spiral form, and attach one of its extremities to a bracket fixed to the
framework of the window. The said end may be connected to a snug by inserting
the end in a V or N shaped saw cut. The opposite or free end of the said spring
is made to grip the metal collar or band aforesaid which it indeed does with such
tenacity as to retain the blind in any desired position.
The said collar or band in lieu of being rigidly connected to the blind roller may
be made preferably detachable.
An alternative method and one suited to the better class of window fittings
consists in connecting the inner end of a steel spring or steel ribbon (well tempered)
to a face plate mounted end wise upon the blind roller and inclosing the opposite
end of the spring in a metal receptacle of box like configuration formed within the
bracket which is connected to the window frame and which constitutes the pivotal
bearing of the blind roller.
The tendency of the spring in this case will be to assume its original form namely
that of being straight; in doing so a circumferential expansion will be exerted by
the spring to grip the interior of the said box or receptacle in which it is contained,
and so exert a brake power or clutch to the blind roller.
The method of operating the blind roller by cord and pulley, coiled spring, or
otherwise, does not form any part of my present invention; any reference to the
opposite end of the blind roller is therefore not essential.
Dated this 29th Mar 1896.
GAVIN STRUTHERS ROBB,
Applicant.

page_text: A New or Improved Frictional Spring Clutch or Brake.
I, GAVIN STRUTHERS ROBB, of 43 Carnarvon Street in the County of the City
of Glasgow, North Britain, Chemist, 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 which relates to a new or improved frictional spring clutch or
brake is applicable to all cylindric bodies moving round an axis either by gravity
or other force or forces and is so designed as to come into operation when the
power (not gravitational) has been removed.
The function of my improved clutch or brake is, negative, that is to say its
tendency as opposed to constant resistance is to save power and let it out the
moment it is opposed in the direction contrary to which that power to which it
was passive was applied. By virtue of its arrangement very little power is
required to set the cylindric moving body in motion, the degree of friction which
held it fast when the power was removed is so nicely adjusted as to prevent
the opposing force namely gravity from accumulating to such extent as to
overcome it at any time.
In describing my invention I shall confine myself to only one form of its
application; namely to a window blind roller.
It is well known that the tendency of such blinds is to run down when not
otherwise opposed. This is due to a counterweight which is usually in the form of
a rod or lath together with the weight of the blind.
In order to resist this tendency aut matically I propose to mount in accordance
with my invention, one of the ends of the blind roller, with a metal collar or band
having the axial stud, preferably of brass; and I take a spring after the manner,
or indeed it may be constituted a part of a clock spring of well tempered steel
coiled in a spiral form, and attach one of its extremities to a bracket fixed to the
framework of the window, The said end may be connected to a snug by inserting
the end in a V or N shaped saw cut. The opposite or free end of the said spring
is made to grip the metal collar or band aforesaid which it indeed does with such
tenacity as to retain the blin in any desired position.
The said collar or band in lieu of being rigidly connected to the blind roller may
be made preferably detachable.
An alternative method and one suited to the better class of window fittings
consists in connecting the inner end of a steel spring or steel ribbou (well
tempered) to a face plate mounted endwise upon the blind roller and inclosing the
opposite end of the spring in a metal receptacle of box like configuration formed
within the bracket which is connected to the window frame and which constitutes
the pivotal bearing of the blind roller.
The tendency of the spring in this case will be to assume its original form
namely that of being straight, in doing so, a circuinferential expansion will be
exerted by the spring to grip the interior of the said box or receptacle in which it
is contained and so exert a brake power or clutch to the blind roller. The method
of operating the blind roller by cord and pulley, coiled spring, or otherwise does not
form any part of my present invention any reference to the opposite end of the blind
roller is therefore not essential.
And in order that my invention may be properly understood and readily carried
into effect, I have hereunto appended one explanatory sheet of drawings in the
several figures of which corresponding parts are marked with the same letters of
reference.
Figure 1 illustrates in front elevation a window blind embodying my invention.
Figure 2, is a transverse section taken on the liues a. b. Fig. 1.

page_text: Figure 3 is a detached view of the frictional spring clutch or brake.
Figures 4 and 5, are end view and longitudinal section respectively of a face plate.
and steel spring illustrating an alternative method of my invention.
Figure 6 is a front elevation of a railway carriage blind to which my invention is
applied.
Figure 7 is a transverse section of the one end of the same showing the spring
clutch or brake and,
Figure 8 is a part section and part end view of the opposite end of the blind.
Referring to Fig. 1 the end of the blind roller there shewn to which my frictional
spring clutch or brake A, is fitted is marked B, and the box or receptacle
containing it is marked C. In the rim of the said box or receptacle C, it will be
seen two saw cats D, and E are formed for the reception of the outer end of the
said frictional clutch A which as seen in Figs. 2, and 3 is formed with an open
loop c, the bent portions of which are pressed into the saw cuts D, and E and held
firmly by friction. The free end of the frictional spring clutch A, is coiled after
the manner of a watch spring and the tendency of the said clutch is to remain
centripetally coiled as shewn in Fig. 3. The end of the collar F, with which the
blind roller is fitted is placed clutch-wise within the coil as seen more particularly
in Fig. 2. The tendency of the blind-roller in whatever position, save when it is.
out its maximum length will be to overcome the spring clutch A, and run down
but by virtue of its springy tenacity this tendency will be automatically resisted..
I have found by experiment that according to the power or force it is required to
resist, the free end should be from an eighth to an inch or thereabouts in excess of
one complete coil.
When it is desired to reverse the blind so as to coil or uncoil it from the back as.
opposed to the position shewn in Fig. 1, the spring clutch A, due to its construction.
and to the saw cuts, is essentially interchangeable. This alone forms features of
special advantage to window blind furniture fitted with my invention. The spring
clutch is readily adaptable to that class of blinds where the pawl and ratchet are
presently used and which would be superseded by my invention.
In the modification shewn in Figs. 4 and 5, it will be there seen that the form of
spring clutch marked A' is the reverse of that shewn in Figs. 2 and 3, its tendency
being centrifugal or to assume its original form namely that of being straight or
approximately so. When placed within its box or receptacle (not shewn in the
drawings) it will exert sufficient frictional expansion as to overcome the power of
the blind and roller set up by gravity.
In the application of the spring clutch to a railway carriage blind as shewn in.
Figs. 6, 7, and 8, the large coil spring H, contained within the box I, acts in the
same manner to the frictional clutch A, as gravity did with the house blind but is
exerted in an opposite direction. To counteract this tendency the direction of the
spring clutch A, is to centripetally coil itself and clutch the collar from the right.
as seen in Figure 7, in which manner it controls the said large spring H and
the blind in its upward motion.
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 frictional spring clutch or brake as and for the purposes herein before
described and shewn on the accompanying drawings.
2. The general arrangement and combination of parts operating substantially as
described and shewn on the accompanying drawings.
D
11
G. S. ROBB,
43 Carnarvon Street, Glasgow, Applicant.