Improvements in Band Friction Clutches.
Year: 1897

page_text: Date of Application, 12th July, 1897-Accepted, 14th Aug.,
1897
COMPLETE SPECIFICATION.
Improvements in Band Friction Clutches.
I, MAURICE HIPPOLYTE CHARLES WASHINGTON FARJASSE, of No. 8 Rue
Labordière Neuilly-sur-Seine, France, 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:-
This invention relates to clutches of the kind in which the driving of a shaft
or the like is effected by the friction of a band as it is unwound from a boss so as
to bear against an enclosing shell, as I shall describe referring to the accompanying
drawings.
As shewn in Figure 1 which is a transverse section of the band, it consists of a
number of wires F laid side by side and held together and to a ribbon A of steel by
solder S, but the solder does not quite reach the face but leaves small spaces e to
hold grease for lubricating the friction surface. After the band is soldered it is
faced externally producing a little flat s on the face of each wire. The wires are of
different lengths so that the band in the course of its length varies in width from
the greatest number of adjacent wires down to a single wire.
Figure 2 is a section and Figure 3 is a front view of a clutch in which the
band above described is employed. Figure 4 is a section on the line 4 4 of
Figure 2. Figure 5 shews to an enlarged scale the winding on a boss of the band
which tapers in width.
nor
the
The boss M keyed on the shaft O has fixed to it the inwardly bent wide end of
the band by a key c; the other end of the band which is only one wire wide, as
shewn in Figure 5 and to a larger scale in Figure 6, terminates against a ring H
which is sunk in the boss but quite free in its groove. On the ring is a helical
rib n of the same pitch as the wires of the band; this rib does not touch the
enclosing shell C but projects far enough to prevent the wire F from passing it.
The shell C is rigidly connected to the pulley P which is to be clutched to the
shaft O. The rib n stops at n¹ where there are two holes o o¹ through the ring H.
In the hole o is fixed by a bend the end of the single wire F with which the band
terminates; the hole o¹ receives the end of another wire fl which has no soldering
steel band. Thus the ring H serves merely to connect
on the
wire of the band to the separate wire f which is wound
boss M, and partly on a ring I loose on the boss, and terminates with a bend
entering a hole in a ring K, which can turn freely on a roller J; this holds the
rings I and K in place. The ring K has a pin h fixed in a widened part h¹, and
engaged in a slot of a ring R. It is by this pin h that the band is unwound so
as to increase its diameter and cause it to bear against the interior of the shell C
with friction sufficient to drive it. The helicoidal vacancy left at the first convolu-
tion of the band is filled in by a plate Q so as to prevent the band from becoming
displaced longitudinally. As the shell C nowhere makes contact with the band,
motion is transmitted to it only when the band is unwound and that in only one
direction. Assuming that the shaft rotates in the direction of the arrow in
Figures 3, 4, 5 and 6, the band turns with the boss, without affecting the shell C
In order to clutch by unwinding the band I apply pressure to the ring R by a

page_text: roller k. As the interior of the ring R is larger in diameter than that part of
the boss which carries it, the effect of the pressure on R is that which may be
understood from the diagram Figure 7 in which the eccentricity of the ring is
exaggerated. The point of the ring is now in contact with the point y of the
boss, but after a complete revolution of the boss, another point makes contact
with y, the ring R being thus as.it were retarded' by the amount; this relative
retardation being transmitted through hand g, f, H, and n to the band F, causes
its unwinding and its pressure against the interior of the shell C, which it carries
round with it. When the pressure of the roller kis relieved the elasticity of the
band, causes the ring R to turn on the boss to its former position, the band closing
in on the boss and releasing the shell C.
The ring R as shewn in Figures 5 and 6 is internally grooved to fit the wedge
shaped part of the boss with which it is in contact, so as to give greater driving
friction.
The roller k may be moved in various ways. One arrangement is shewn in
Figure 3. On a fixed bracket is pivotted a ratchet wheel on an axis m which
carries a triangle arranged to act on the one arm y of a lever, which is pivotted
atv and carries on its other arm the roller k. The ratchet t is turned by a link d
from a lever which is pivotted at and raised by a spring z. An adjustable
spring. X urges the roller k against R, but when, by pulling down the lever v
the triangle is turned partly round, one of its angles pushes y away and raises the
roller k, thus causing unclutching. When the lever is again pulled the triangle l
presents one of its sides to g and clutching is effected.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what I
claim is:
. 1. For a band friction clutch, a band consisting of wires of decreasing length
soldered together and to a metal ribbon, the soldering being such that spaces for
grease are presented on the rubbing face, substantially as described.
2. Fixing the band to the boss by a key holding the bent end of the band in a ;
slot of the boss.
3. In combination with the boss and band a helicoidal plate filling the vacancy
at the first convolution of the band.
4. The free ring H with helical rib
the separate wire f.
connecting the last wire F of the band to
5. The ring I interposed between the boss and the last convolutions of the wire f.
6. The ring K connected to the end of the wire f and having a pin engaged in
slot of the eccentric ring R.
h
3
7. In combination with the ring R a roller adapted to press it on the boss so
as to relatively retard the end of the band and to effect clutching by its unwinding. 4
Dated this 12th day of July 1897.
ABEL & IMRAY,
Agents for the Applicant.