Improved Back Pedal Brake.
Year: 1898

page_text: Date of Application, 1st Nov., 1898-Accepted, 3rd Dec.,
1898
Improved Back Pedal Brake.
I, JOHN DAVITT KEATING, of 117, Grand Street, Middletown, County of Middlesex,
State of Connecticut, U.S.A., Machinist, do hereby declare the nature of my inven-
tion, and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement :-
Heretofore brakes for bicycles have been known in which the brake was applied
by back pedaling, but in general the back pedaling must be continued in order to
hold the brake applied. In the present construction the brake is applied by the
first backward movement or retardation of the normal movement of the pedals,
and the brake may then be held in action by holding the pedal in stationary
position, thus relieving the rider of exertion beyond the mere resting of the foot on
the pedal and holding it; and the brake may be applied with greater or less force
according to the pressure on the pedal.
My device is constructed as follows, reference being had to the accompanying
drawings, in which :-.
Fig. 1 is a side elevation of so much of a bicycle as is needed to give an idea of
the relation of parts;
Fig. 2 is a vertical section extending through the wheel hub, and through the
compression cams or wedges;
Fig. 3 is a vertical section through the hub and its friction driving clutch;
Fig. 4 is a vertical cross section through a wheel hub, showing part of frame;
Fig. 5 is a perspective of the compression cams or wedges.
The numeral 1 indicates the axle of the driving wheel. 2 denotes the hub, which
turns on the axle, ball bearings of usual construction being interposed. The hub
has a cam ring 3, of hardened steel, secured thereto, preferably by a stud or pin on
the hub entering a recess in ring 3, and the driving sprocket or ring 4, surrounds
said clutch piece or cam ring, the balls a being interposed between the teeth of the
clutch piece and the inside surface of the driving sprocket, and preferably in a
groove in the sprocket ring. This permits a rotation of the sprocket ring in one
direction (backward) without moving the hub, but when the sprocket ring is driven
forward the balls pinch between the inside of the sprocket ring and the inclined
faces of the teeth on the cam ring, and cause the clutch wheel and hub to rotate
with the sprocket ring. Other automatic clutch gear might be used to the same
effect in this relation.
Surrounding a cylindrical extension 2" of the hub, I supply a wearing ring 5.
This wearing ring is preferably a broken ring, and may be of hardened steel, bronze,
or other material which will endure much wear. If the ring is a broken ring it can
be readily renewed. A spline or stud 2b projecting from the hub causes this ring 5
to partake of any rotary movement of the hub, and this may be the same spline or
stud which holds the cam ring against rotation independently of the hub.
Surrounding the wear piece or ring 5, I place the cam wedges 6, these wedges
constituting a very important part of the invention. The wedge pieces 6 are curved

page_text: on their inner faces, and conform generally to the wearing ring on which they rest.
The outer face of each piece 6 has an inclined surface or tooth 6ª, and a projecting
stop 6. The total length of the wedge pieces 6 is a little less than the circum-
ference of a circle, leaving a space 6, into which space a piu or stud 4, projecting
from the side of the sprocket 4, enters. When turning forward, this pin or stud
causes the wedge pieces 6 to partake of the movement of the sprocket ring 4.
Balls bare interposed between the faces of teeth 6ª and the cup 7, and when the
wedge pieces are moved in one direction, these balls find lodgement against
shoulders or stops 6b; but when the wedge pieces move in reverse direction these
balls are wedged between the pieces 6 and cup 7. The cup 7 which encloses the end
of the hub, is prevented from rotating by a stud 8, projecting at the side of the frame 9.
Or the cup 7 may be otherwise secured against rotation, either to the fixed axle, or
to the frame.
Inside the cup 7, there is preferably a groove, and in this groove, between the
toeth of the wedges and the cup, are balls b, having a limited movement when the
sprocket ring and wedge pieces are moving forward. A reverse movement of
the sprocket ring causes the inclined faces of the wedge pieces to wedge firmly
against the balls, and thus press on the wear piece 5, the balls being held against
outward movement by cup 7. The strains are all compression strains, except on
ring 7.
When the sprocket ring 4 and the cam wedges are moved, as stated, the balls b
are caught between the inclined faces of teeth 6ª, and the cup 7, and, as cup 7 cannot
rotate, the cam wedges 6 are also held against rotation, thus acting to brake or
retard the vehicle. In fact the pressure may be so great as to lock the wheel; but
a moderate backward pressure on the pedal causes such a frictional contact of the
parts as to cause a very effective retardation. The first backward movement of
the sprocket ring, caused by. back pedaling, releases the clutch engagement
of hub 2 with ring 4, and an instant later engages the wedges 6 with the cup 7.
The compression of these wedges 6 by reason of the balls interposed between the
teeth 6ª and the cup 7, causes these wedges 6 to bind firmly on the wear piece 5,
which is to all intents a part of the hub. The forward movement of the sprocket
ring by means of the pedal immediately unlocks the brake and re-engages the
friction driving clutch.
Three teeth and three balls are shown in each clutch, but the number may vary
according to circumstances.
The wear piece 5 is made in form of a broken ring, so as to be easily adjustable
and removable. The operation of the device would be the same if the wedge cams
bore directly on the hub; but to prevent wear of the hub it is better that a wear
piece be interposed.
In the same way the clutch ring 3 might be integral with or secured to the hub;
but as the result of experience it is preferred to make these parts easily removable.
As shown, they are simply slipped over the end of the hub, and held against
independent rotation by a spline, as is common in mechanics.
This brake may be applied to many wheels of common construction, with very
slight change. The cup 7 is common to several well known wheels. The wedge
pieces 6 are easily made and applied; the driving clutch is simple, and can be easily
applied to most wheel hubs; but where a good clutch is present, such will co-act
with the cam wedges without difficulty. The balls can be readily procured. Rollers
might be substituted, but balls are generally preferable.
As illustrated this device is applied to a wheel driven by a pedal and chain, but
it will be readily understood that it is immaterial how the sprocket ring is driven,
and a skilled mechanic will readily adapt this brake device to many different
machines.
In this brake there are no springs and no levers. The entire operation is by
cam or wedge action. The parts exposed to wear are easily replaceable without
special tools.

page_text: 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. In a cycle, the wheel hub having a friction coupling operatively engaging the
hub to secure a forward movement, and a braking or retarding friction mechanism
connecting to the wheel and frame, said couplings being alternately thrown into or
out of operation by the pedal, substantially as described.
2. The combination of the rotating driving member having an internal bearing,
the hub with cam bearing surfaces and interposed balls, and the enclosing cup and
wedge pieces and the interposed balls, to secure the pressure of said wedges on
the hub by the backward action or retardation of the pedal, substantially as
described.
3. The driving sprocket having internal clutch coupling leading to the hub, and
the retarding clutch coupling operating by reversal or retardation of the pedal
movement, and the interposed wear piece between the brake clutch and the hub,
all substantially as described.
4. The novel combinations and arrangements of the parts constituting a back
pedal bicycle brake, substantially as described.
S. S. BROMHEAD,
Agent for Applicant, 171, Queen Victoria Street, London, E.C.