Improvements in Brakes and Clutches.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in Brakes and Clutches.
I, LÉON LEFEVRE, of 251, Rue de Vaugirard, Paris, in the Republic of France,
Clock-maker, do hereby declare the nature of this invention to be as follows:-
This invention relates to an arrangement of friction surfaces employed either
in connection with flexible band brakes, or in connecting and disconnecting
apparatus, or in braking, starting, slackening and stopping the movement of
parts, by means of a rubbing or frictional effort variable at pleasure; and the
object of the invention is to increase the efficiency of such devices by producing
a wedging action between the friction surfaces by which their adhesion is con-
siderably increased.
According to one arrangement of my invention the friction takes place between
the external surface of a pulley and a series of shoes fixed on a flexible band
surrounding the pulley, the rim of which presents one or more grooves in which
the said wedge-shaped shoes engage.
When applied as a brake to the back wheel of a bicycle for example, besides the
grooved pulley fixed on the hub of the wheel and the said flexible band, I also
provide a box which can slide on the frame without being able to turn, and which
serves both as a protecting shield for the brake, as a fixed point of attachment
for the flexible band, and as a means of regulating the tension of the chain. This
brake comes into action when the free end of the flexible band is pulled.
According to another arrangement the friction is produced onl the
internal surface of hollow pulley by the
a
contact of a series of
movable segments disposed radially in the interior of this pulley. The radial
extension of these segments is effected, for example, by means of a conical sleeve
sliding on the shaft. The form of the friction surfaces may be varied according
to the shape of the grooves on the rim of the pulley and by the corresponding
angular or curvilinear shape of the segments which engage in the said grooves
in order to produce the wedging effect by which the adhesion of the parts is
increased.
100A

page_text: Improvements in Brakes and Clutches..
I, LÉON LEFÈVRE, of 251, Rue de Vaugirard, Paris, in the Republic of France,
Clock Maker, 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; -
My invention relates to that class of brakes in which the friction of a flexible
plate on the rim of a pulley, forming part of a mechanism in motion, produces
a resisting force to be disposed of at will, to act in a contrary direction to that
of the motive power applied to the said mechanism, and the invention has for its
object to give to a brake of this class a very high efficiency.
For this purpose I substitute for the cylindrical surfaces heretofore adopted for
the friction pulley and flexible plate of the brake, revolving surfaces of variable
profile formed of straight lines inclined to the axis, or of curved lines so combined
as to provide a very large contact surface but of very small width transversely.
This arrangement insures the double advantage of increasing the surface of
friction without increasing either the diameter of the pulley or the width of its
rim, and of causing the brake plate and pulley to act in the manner of a wedge,
the one entering the other, whereby there may be obtained a very great frictional
braking force in proportion to the dimensions of the apparatus.
Another advantage afforded by the increased friction consists in the corre-
sponding diminution in the effort to be exerted on the free end of the flexible
plate in order to obtain the same braking effect.
.
A brake constructed according to my invention comprises essentially a pulley
the rim of which is in the shape of a groove or of a wedge projection, and a flexible
plate provided with a series of shoes of a form inverse to that of the rim. The
pulley rotates with the apparatus or machinery the speed of which is to be
decreased at will. The flexible plate embraces the friction pulley, and is fixed
at one of its ends to a fixed part of the frame of the machine. Its opposite end,
capable of tangential displacement, is connected with a suitable operating device.
I have shown in the accompanying drawing, and by way of example, my system
of brake as applied to a bicycle.
Figure 1 is a view of the side of the apparatus that fits on the rear wheel of the
-bicycle.
Figure 2 is a cross section taken on the axial line.
Figure 3 is a plan view.
Figure 4 shows the brake plate separately.
Figures 5, 6, 7, 8 and 9 show a series of modifications of my brake differing
from each other in the form of the friction surfaces.
The brake shown in Figures 1, 2, 3 and 4 is made in view. of its being fitted
to the rear wheel of a bicycle.
It is composed of a pulley a, a flexible plate b, and a casing c, which serves
both as a cover and a support.
The rim of the pulley a has a hollow groove d, V-shaped in cross-section; it
is fixed to the hub of the rear wheel by means of screws or bolts.
To the flexible plate bare fixed a certain number of shoes e, of a shape corre-
sponding to the groove of the rim; the apex of the wedge thus formed is some-
what truncated in order to prevent the shoes from reaching to the bottom of
the groove d
One end, f, of the plate is fixed to the casing c and the other end, g, is provided
with an arm h, to which is connected the operating cord, chain, or rod.
The casing c carries at its side a rectangular boss i so arranged as to engage

page_text: and slide in the recess of one of the branches of the rear fork of the machine; the
said boss has a central opening through which passes the axle of the wheel, and
it is provided with a screw-threaded rod k, a tension device /, and a nut m, whereby
the position of the axle with respect to the frame, and consequently the tension
of the sprocket chain, may be regulated.
The casing c being fixed to the frame by means of nuts which also hold in
position the axle of the rear wheel, the brake plate b has a fixed support at f.
So long as the said plate bis expanded the pulley a is free to revolve; but as
soon as the end g is acted upon so as to apply the plate to the pulley, the shoes e
come into contact with the walls of the groove d'and act as so many wedges to
produce great friction.
The direction in which the flexible plate bis wound round the pulley is such
that the pull caused by the friction falls entirely on the fixed end, f, and that
the operating device connected to the other end, g, has only to transmit a very
slight effort.
Figures 5, 6, 7, 8 and 9 show several modifications of the shapes of the friction
surfaces which may be adopted for the rim of the pulley and the fixed shoes on
the flexible plate. It is evident that my invention is not limited to either the shapes
or dimensions shown in the drawing; I may, for example, place side by side on
the same rim and the same flexible plate, friction surfaces having several of the
shapes shown, and the number of which may be greater or less according to the
frictional force to be obtained.
I reserve to myself the right of modifying the herein before described brake in
any way which may be necessary to adapt it to cars, engines, elevators for heavy
goods, or any other machinery requiring a brake.
Any known arrangement may be employed for operating the brake, which
exerts a tractive effect upon the flexible plate either directly or through the
medium of a lever, screw, or other suitable device.
Figures 10 and 11 show a brake pulley having a groove d adapted to receive
the brake shoes e, and two grooves e adapted to receive cords p, one end of each of
which is connected to the Hexible plate 6 while the other end is operated by hand.
When the cords are pulled they are pressed into the grooves c, are drawn by
friction in the direction of rotation of the pulley, and consequently exert a greatly
increased tractive effort upon the flexible plate b.
I reserve to myself in particular the right of applying the characteristic part
of my invention, which consists in the angular or curvilinear shape given to the
friction surfaces of the pulley and flexible plate, not only to flexible plate brakes,
but also to the several devices based on the same principle, such as clutches used
for putting machinery into or out of gear.
In this case, it is advantageous to replace the flexible plate surrounding the
rim of the pulley by two or more segments acting radially inside a recessed pulley.
According to my invention, the inner face of the rim of the pulley, instead of
being cylindrical, as in apparatus now in use, is provided with several circular
grooves in which engage the terminal. surfaces, of inverse shape, of the movable
segments. arranged within the pulley, where they may be radially operated by
any suitable device, such as a cone capable of being moved endwise of the axis of
the pulley, for example.
Figure 7 shows an apparatus of this description, in which a is a loose pulley on
the shaft, bb are segments arranged. within the pulley, and which rotate with
the shaft; B is a conical sleeve capable of being moved longitudinally on the said
shaft in such manner as to move the segments 6 radially and to press them
against the rim of the pulley a during the operation, of putting into gear. The
surfaces of the pulley and segments which come in contact with each other being
of the angular shape which characterises my invention, determine considerable
adherence on account of their fitting into one another, and they allow of practically
transmitting very great power without the necessity of exerting very great
pressure on the conical sleeve B..
1

page_text: The same device may be used as a brake by making one of the friction surfaces
stationary and by putting the other in connection with the moving mechanism
the speed of which is to be moderated; I purpose notably to apply this device to
motor-cars either as a brake or clutch for the operation of putting into gear.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, I declare that what
I claim is:
1. A brake for bicycles comprising a pulley fixed to the rear wheel, a flexible
plate surrounding the rim of the said pulley and carrying a series of shoes on its
inner face, the said plate being fixed at one of its ends to the frame of the bicycle
and connected at its other end with a suitable operating device, the said brake
being characterized by the angular or curvilinear shape given to the friction
surfaces for the purpose of increasing the frictional force or power produced
between the said surfaces, substantially as described.
2.A brake for bicycles comprising a pulley fixed to the rear wheel, a flexible
plate surrounding the said pulley and carrying a series of shoes, the angular or
curvilinear surface of which shoes fits that of the rim of the pulley, in com-
bination with a casing capable of sliding on the frame of the bicycle without being
able to rotate, and serving, at one and the same time, as a protecting cover for
the brake, a point of support for the flexible plate, and a hub for adjusting the
tension of the sprocket chain, substantially as described.
3. A clutch having a hollow pulley and radially movable segments, acting by
friction on the inner face of the rim of the pulley, characterized by the arrange-
ment of circular, angular, or curvilinear grooves in the inner face of the rim
and on the outer face of the segments, for the purpose of increasing the adherence
of the surfaces in contact, substantially as described,. and shown in the accom-
panying drawings.
4. The combination with a rotatable member, of a corresponding member in
the plane of rotation of said first named member, and adapted for frictional
engagement therewith, one of said members being provided at its engaging
surface with a groove, the walls of which are at an angle with respect to the axis
of rotation, and the corresponding member having its corresponding surface
formed with a projection of a shape inverse to that of the said groove, and means
for moving said members. into frictional contact, substantially as and for the
purpose described.
5. The combination, with a pulley adapted to be secured to a rotatable axle,
of a brake band surrounding said pulley and adapted to engage the same, one
end of the band being movable, and a stationary casing surrounding the brake
band, the other end of said band being secured to. the said casing substantially
as described.
6. The combination, with a pulley adapted to be secured to a rotatable axle,
of a brake band surrounding said pulley and adapted to engage the same, one end
of the band being movable, a casing surrounding the brake band, a boss integral
with the casing arranged on one side thereof, said boss being adapted to slide
upon the frame of a bicycle, and having a central aperture for the passage of said
axle, the other end of the brake band being secured to the casing, and a wheel-
adjusting device connected with the said boss, substantially as described.
7. In a bicycle or other vehicle, a casing provided with a boss adapted to slide
in the frame of the vehicle and apertured to receive the axle of the wheel to be
braked, a brake in said casing, means for applying the brake, and a chain-adjust-
ing device consisting of a screw-threaded rod secured to the casing, a tension
bracket or device through which passes said rod, and a nut screwing on to the
rod and engaging the bracket, substantially as described.
8. The combination of a pulley having circular grooves one or more cords
wound round the pulley, a flexible plate connected at one end to the said cords,
and at the other end to a fixed point, and shoes carried by the flexible plate, and

page_text: engaging, after the manner of wedges, in a groove in the pulley, substantially as
described.
9. A clutch having a hollow pulley and segments movable radially and acting
upon the internal face of the rim of the pulley: the essential feature of which
clutch is the arrangement of circular grooves of angular or curvilinear section
on the internal face of the rim, and of corresponding projections on the exterior
of the segments, for the purpose of increasing the frictional adhesion by the
wedging together of the surfaces in contact, substantially as described.
Dated this 26th day of June 1800
L. LEFÈVRE.
Per W. H. Beck,
115, Cannon Street, London, E.C., Agent.