Improvements in Brake Mechanism for Bicycles and similar Vehicles.
Year: 1896

page_text: Date of Application, 28th May, 1896
Complete Specification Left, 29th Mar., 1897-Accepted, 28th May, 1897
PROVISIONAL SPECIFICATION.
Improvements in Brake Mechanism for Bicycles and similar
Vehicles.
I, PERRY ERNEST DOOLITTLE, of 180 Sherbourne Street, City of Toronto,
Province of Ontario, Dominion of Canada, Physician, do hereby declare the nature
of this invention to be as follows:-
My invention relates to brake mechanism for bicycles and similar vehicles, in
which the driving means are employed to propel as well as
to reverse the
movement of the vehicle. The objert of my invention is to provide the driving
means with a fixed brake whereby the reversing action of the driving means will
directly operate the brake to retard to a greater or less degree the forward
movement of the vehicle, according to the amount of pressure applied to the driving
means. To this end my invention consists of the means as hereinafter described
and claimed.
The invention is illustrated in the accompanying drawings in which
Fig. 1 is a side elevation of a pedal shait, chain and sprocket wheel with my
invention attached;
Fig. 2, a plan of the axle and hub of the driving wheel with sprocket and brake
mechanism;
Fig. 3, a view in elevation partly in vertical section of matters in Fig. 2;
Fig. 4 a face view of an inner brake collar;
Fig. 5 an inner face view of the sprocket disc;
Fig. 6, an inner face view of the friction disc, and
Fig. 7, a detail edge view broken away showing the formation of the shouldered
and inclined teeth forming the brake clutch;
Fig. 8 a view similar to Fig. 2 of a modification;
Fig. 9, an end view of hub and brake disc in the modification with friction dise
removed, and
Fig. 10, an outer face view of the modified form of sprocket wheel.
My invention is here illustrated as applied to a bicycle of the ordinary form,
employing a sprocket and sprocket chain as the driving means, operated from the
pedal shaft.
Referring to the drawings, A A' are the spindle and hub, respectively, of a rear
driving wheel and B is the sprocket end of the hub. Mounted on the hub are a
brake collar, C, and a sprocket wheel D. The collar C is rigidly secured to the
hub, but the sprocket D is so mounted thereon as to permit it to be given in addition to
its forward rotation with the hub, a slight backward rotary movement on the hub and
also a lateral sliding movement thereon. The collar C is provided on its inner face
with raised teeth or sections E, in the form of inclines the highest parts of which
terminate in abrupt inwardly bevelled shoulders 6'. The sprocket D on its inuer
face is provided with similar teeth, E' and shoulders. These respective teeth or
sections together form a clutch, and when set together the shoulders & of the
respective teeth engage, their inner bevelled faces meeting, and the inclined faces
of the teeth are in close and continuous contact, so that in their locked position the
thinnest portions of the collar rest against the thickest portions of the sprocket
wheel.

page_text: H is a disc plate, having an inwardly extending annular rim, b', and rigidly
mounted on the spindle A. Within the rim & the face of the plate is provided
with a frictional surface i, which may be composed of leather, rubber or other
suitable frictional material. The outer plain face d¹ of the sprocket wheel acts as
a friction plate and is adapted to enter within the rim of disc H and impinge
against said disc, as hereinafter described.
R is a pin or lug on the outer face of the disc H to contact with the forked
frame S, for the purpose of preventing the disc from turning with the sprocket when
the pressure is applied.
G is a spring arm secured on the edge of the collar C at one end by means of
two screws, g', 92, while the free end of said spring bears against a pin projecting
from the inner face of the sprocket, the said pin holds the spring arm up from the
collar, and the united function of the pin and spring is to lock the sprocket wheel
in firm engagement with the collar, as hereinafter described. The spring arm is
provided with the extra screw, 92 arranged in front of the screw g' by which the
pressure of the spring arm upon the pin and sprocket are adjusted, by which more
or less back pressure of the driving means will be necessary to operate the clutch
and control the extent of the braking operation, or the spring arm may be screwed
down thereby so tightly as to prevent the operation of the brake altogether.
The operation of the device is as follows:-In the act of back pedaling, or
reversing the movement of the wheel to check its forward direction, the power
exerted on the sprocket tends to turn it slightly backward on the hub. This
reverse action causes the engaging sections of the respective faces of collar and
sprocket to ride upon each other and forces the sprocket in against the face of the
friction disc H. The pressure of the sprocket wheel against the disc increases as
the inclines rise upon each other. The same backward movement of the sprocket
overcomes the resistance of the spring arm and the pin on the sprocket is forced
under the end of the arm, but as the sprocket and pin are turned backward, the
pressure of the spring increases and when the backward pressure is relieved from
the sprocket the action of the spring is such as to still hold the sprocket against
the friction plate H, until released by a forward pressure of the driving means
which carries the sprocket beyond the holding force of the spring. When the
collar and sprocket are locked together in their normal condition the pressure of
the spring holds them in this position until the reverse pressure of the driving
means is again exerted to overcome it.
It will be seen that the same brake action of the two discs carrying the engaging
inclined teeth, may be accomplished whatever may be the means of reversing the
movable disc and whether the same is a sprocket disc or not, whenever such action
is sufficient to force the inclined teeth upon each other-the amount of friction
produced being controlled by the amount of back pressure exerted. When used
with an ordinary bicycle after being locked by the spring the brake is held so
without increasing or continuing the backward pressure, and the brake is released
by a simple forward thrust of the pedal which will carry the sprocket wheel
forward and force the inclined engaging teeth in opposite directions, separating
the discs. When not in use the bevelled shoulders of the teeth will hold the
sprocket wheel tightly against the collar, the spring arm retaining it in that
position.
Instead of making the brake surface d' of the sprocket wheel integral therewith,
it may be made separate therefrom, and form a separate dise on the same hub
and revolve therewith, and be driven laterally against the friction plate by the
back motion of the sprocket. In such case the collar C is dispensed with. The
teeth E of the sprocket are shifted to its opposite side as well as the pin, ², and
the said separate disc is provided with the engaging teeth E, and spring G. In
such case the said separate disc is driven laterally on the hub and not the sprocket.
In this modification as shown in the drawings, Figs. 8, 9 and 10, the separate disc
is indicated by F. The sprocket end of the hub B, is provided on its periphery
with projections, or lugs u, and the sprocket D with recesses & on its inner

page_text: circumference. When the sprocket is slid on to the hub, the projections a³ of
the latter, enter the recesses d. The sprocket is then pushed against the rim a³ of
the hub and turned, so as to bring the recesses d², out of engagement with the
projections or lugs a², whereby the sprocket is held against lateral movement on
the hub by said lugs. The disc F is provided with recesses f¹, which when this
disc is placed on the hub, engage with the lugs a². The disc F is by this engage-
ment made to rotate with the hub, but is also at the same time permitted a lateral
movement thereon.
It will be seen that the action of the brake is entirely automatic, being controlled
by and corresponding to the pressure exerted by the rider in checking the forward
movement of the wheel in back pedaling.
The parts of the brake are made to fit so closely as to wholly exclude dust
and dirt.
Dated this 28th May 1906
F. WISE HOWORTH,
Applicant's Agent.
COMPLETE SPECIFICATION.
Improvements in Brake Mechanism for Bicycles and similar
Vehicles.
I, PERRY ERNEST DOOLITTLE, of 180 Sherbourne Street, City of Toronto,
Province of Ontario, Dominion of Canada, Physician, 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 brake mechanism for bicycles and similar vehicles in
which the driving means are employed to propel as well as to reverse the movement
of the vehicle, and it has for object to provide in connection with such driving
means, brake mechanism whereby the reversing action of the driving means will
not only directly operate the brake to retard, to a greater or less degree, the
forward movement of the vehicle according to the amount of pressure applied to
the driving means, but the brake shall be locked or held in the "on" position until
the driving means are again operated in the forward direction. I proceed to
describe my invention chiefly with reference to its application to bicycles driven
by pedals, but its application to motor cars or vehicles driven by power will be
obvious.
To this end my invention consists in an improved construction of brake
apparatus as I shall now describe with reference to the accompanying drawings
wherein
Figure 1 is a side elevation showing part of a bicycle with pedal shaft, chain,
and sprocket wheels and my brake mechanism applied thereto.
Figure 2 is a plan and Fig. 3 a side elevation, partly in vertical section,
showing, to a larger scale than Fig. 1, the axle and hub of the driving wheel
with one construction of sprocket wheel and brake mechanism according to this
invention.
Fig. 4 is a face view of an inner brake collar with spring.
Fig. 5 is an inner face view of the sprocket wheel or disc with locking pin.
Fig. 6 is an inner face view of the friction disc.
Fig. 7 is a part detail edge view, showing the formation of the shouldered and
inclined teeth forming the brake clutch.
My invention is shown as applied to a bicycle of the ordinary form, employing
sprocket wheels and sprocket chain as the driving means operated from the pedal
shaft.

page_text: Referring to the drawings, A, A, are the spindle and hub, respectively, of a
rear driving wheel, and B is the sprocket wheel end of the hub. Mounted on the
bub are a brake collar C and a sprocket wheel D. The collar C is rigidly secured
to the hub, but the sprocket wheel D is so mounted thereon as to permit it to be
given, in addition to its forward rotation with the hub, a slight backward rotary
movement on the hub and also a lateral sliding movement thereon. The collar C
is provided on its inner face with raised or projecting teeth or sections E in the
form of inclines the highest parts of which terminate in abrupt inwardly bevelled
shoulders. The sprocket wheel D on its inner face is provided with similar
teeth E and shoulders. These respective teeth or sections together form a
clutch, and when set together the shoulders of the respective teeth engage,
their inner bevelled faces meeting and the inclined, faces of the teeth being in
close and continuous contact, so that in their locked position the thinnest
portions of the collar rest against the thickest portions of the sprocket wheel
and vice versa.
His a disc plate having an inwardly extending annular rim h and rigidly
mounted on the spindle A, so as to be secured against rotation around the spindle;
but the said dise is at the same time readily removable from the spindle when the
latter is disengaged from the frame. Within the rim 4, the face of the plate is
provided with a frictional surface i, which may he composed of leather, rubber, or
other suitable frictional material. The outer plain face d' of the sprocket wheel
acts as a friction plate and is adapted to enter within the rim of the disc H and
impinge against the said dise, ns hereinafter described. The rim of the dise H
extends over the outer peripheral edge of the sprocket wheel so as to keep the
frictional surface of the disc free from all foreign matter that would tend to
obstruct its operation; it also serves to exclude dust and dirt from the other
parts of the brake and clutch mechanism. R is a pin or lug projecting fram
the outer face of the disc H so as to act against the forked frame S for the
purpose of preventing the disc from turning with the sprocket wheel when the
brake pressure is applied. This pin or lug R may conveniently extend through
the fork S.
G is a spring arm secured on the periphery of the collar C near one end by
means of two screws g', 92 while the free end of the said spring bears against a
pin, projecting from the inner face of the sprocket wheel. The said pin holds
the spring arm up from the collar, and the united function of the pin and spring is
to lock the sprocket wheel in firm engagement with the collar as hereinafter
described. The spring arm G is provided with the extra screw g, arranged in
front of the screw g', so that the pressure of the spring arm upon the pin and
sprocket wheel can be adjusted and so that more or less back pressure of the
driving means will be necessary to operate the clutch; or the spring arm can, by
means of the screw g, be screwed down so tightly as to prevent the operation of
the brake altogether. The provision of means whereby a small amount of back
pedalling is not liable to apply the brake is a matter of considerable practical
importance. I secure this end by providing that the differential movement of the
sprocket wheel and hub cannot take place until some definite force, which should
be considerable, is applied. The amount of this force can be adjusted to the
requirements of the rider. Instead of the pin and spring arrangement just
described other equivalent arrangements may be adopted, such as the spring plate
or friction band hereinafter described, the essential feature being that until a
definite force is applied the relative or differential movement of the parts which
must take place before the brake acts is not permitted. The same arrangements
prevent the brake from being released until sufficient force is applied in the
reverse direction.
The operation of the device is as follows:-In the act of back-pedalling or
reversing the movement of the wheel to check its forward direction, the power
exerted on the sprocket wheel tends to give it a differential movement relatively to
the hub, that is to turn it slightly backward on the hub. This reverse action

page_text: causes the engaging teeth or sections E, E of the respective fices of the collar C
and sprocket wheel D to ride upon each other and forcas the sprocket wheal
against the face of the friction dise H. The pressure of the sprocket wheel
against the said disc increases as the teeth or inclines rise or slide upon each other.
The same backward movement of the sprocket wheel causes the pin to overcome
the resistance of the spring arm G, and to be forced under the end of the arm, but
as the sprocket wheel and pin are turned backward, the pressure of the spring
increases, and if the backward pressure is relieved from the sprocket wheel, the
action of the spring is such as to still hold the sprocket wheel against the friction
disc H until released by the exertion of a forward pressure sufficient to cause a
differential movement of the sprocket wheel and hub in the reverse direction and
turn the sprocket wheel so as to release it from the helding force of the said spring.
Upon this reverse action of the sprocket wheel, the incline engage and positively
withdraw the brake dise out of action, and keep it locked out of action. Tais
positive withdrawal is an important detail of my invention. If the bick pressure
on the pedals be continued, not only will the braking be continued, but a bak-
wardly retarding action will be exerted upon the driving wheel as if the pedal
cranks were positively connected to the driving wheel. When the collar and
aprocket wheel are locked together in their normal condition, the pressure of the
spring arm G against the sprocket pin 2 will hold them in this position until the
reverse pressure of the driving means is again exerted to overcome it.
It will be seen that the same brake action of the two parts carrying the
engaging inclined teeth E, E can be accomplished, whatever may be the means of
reversing the movable part and whether the same is a sprocket disc or not, when-
ever such action is sufficient to force the said inclined teeth upon each other, the
amount of friction produced being controlled by the amount of back pressure.
exerted. When used with an ordinary bicycle, after being locked with the spring
the brake is held so locked without increasing or continuing the backward
pressure, and the brake is released by a simple forward thrust of the pedal which
will carry the sprocket wheel forward and rotate the inclined engaging teeth
relatively in opposite directions, thereby separating the discs d' H. When not in
use, the bevelled shoulders of the teeth will hold the sprucket wheel tightly
against the collar, the spring arm G retaining it in that position.
Instead of making the brake surface d' of the sprocket wheel integral therewith,
it may be made separate therefrom and form a separate disc on the same hub so as
to revolve therewith and be driven laterally against the friction-plate by the
backward motion of the sprocket wheel. In such a case the collar C is dispensed
with.
Fig. 8 is a side elevation, Fig. 9 a vertical longitudinal section and Fig. 10 a
cross section on the line of Fig. 8 showing such a modified construction of the
brake mechanism. Fig. 11 is an outer face view of the sprocket wheel used in such
modified arrangement. The teeth E and pin of the sprocket wheel D are in
this ease placed on the outer side of the sprocket wheel, and the said separate brake.
dise indicated at F, is provided with the engaging teeth E and spring arm G. In
this case it is the said separate disc F that is movable laterally on the hub and not
the sprocket wheel. In this modification the sprocket end of the hub B is provided
on its periphery with projections or lugs a' (Fig. 10) that are of less length than
the hub B (Fig. 9), and the sprocket wheel is provided with corresponding
recesses (Fig. 11), on its inner circumference. The arrangement is such that
when the sprocket wheel is being slid upon the end B of the hub, the projections a
of the latter will enter and pass through the recesses d of the former, and when the
sprocket wheel has been pushed back against the rim a of the hub it can be partly
rotated on the hub into its normal position in which its recesses d' are out of
engagement with and not opposite to the projections or lugs a² of the hub, so that
the sprocket will be held against lateral movement on the hub by the said lugs.
The disc F is provided with recesses ", (Fig. 10) which, when this disc is placed
on the hub, engage with the lugs a. The disc F is, by this engagement, made

page_text: to rotate with the hub, but is also, at the same time, permitted to move laterally
thereon.
In this modified construction, the lateral movement is confined to the sepirate
brake disc F so that any possible danger of injury to the driving means due to
sidewise strain on the sprocket wheel and change of alignment of the chain that
might obtain with the arrangement shown in Figs. 1 to 7 inclusive, is obviated.
In other respects the operation of the modification shown in Figs. 8 to 11 inclusive
is similar to that of the arrangement shown in Figs. 1 to 7 inclusive, the brake
dise F being pressed, on the application of backward pressure to the pedals, against
the brake disc H which is prevented from forward rotation on the axle A by the
pin R.
Fig. 12 shows in plan and Fig. 13 in vertical section, brake mechanism according
to this invention with another construction of the locking means used for holding
the brake normally out of operation and for locking it in the "on" or operative
position. Figs. 14 and 144 are inner face views of the spring and sprocket wheel
respectively used in such modification. In this arrangement the locking means
consist of a serrated spring disc or ring L, stamped out of thin steel and placed on
the hub B, so as to bear against the inner face of the sprocket wheel D. The inner
periphery of this spring is formed with pairs of slits at intervals and the metal
between each pair of slits is bent so as to form recesses m and Hanges m¹. The
recesses enable the spring to be slipped over the projections a² on the hub and the
flanges m' are adapted to be held between the segments of a small rim or collar o
on the hub so as to prevent the rotation of said spring. The teeth 7 of the disc are
bent or curved outward, so as to bear strongly against the inner face of the sprocket
wheel and stiffen the spring action of the disc. At certain intervals the sprocket
wheel D is provided on its inner face with notches or depressions d³ with which
engage correspondingly-situated teeth on the spring disc L, which teeth by such
engagement constitute spring catches which will effectually prevent the too free
rotation of the sprocket wheel and the consequent undesired operation of the brake
during ordinary riding, and will lock the sprocket wheel and brake-disc F against
any pressure except that produced by the intentional checking of the forward
movement of the driving means. When such action has been exerted sufficiently
to turn back the sprocket wheel and overcome the resistance of the spring-disc, the
latter will still hold the sprocket wheel in the turned back position and the brake-
dise F against the friction-disc H until these parts are released by a sufficient
forward pressure of the driving means which turns the sprocket-wheel forward and
into its normal position, spring teeth or catches on the spring disc entering
the notches d³ in the sprocket wheel and holding it in that position.
Fig. 15 shows partly in side elevation and partly in vertical section my brake
apparatus provided with a further modified form of spring locking device. Fig. 16
is a face view of the sprocket wheel with locking device detached from the hub.
In this arrangement the locking device consists of a circular metal collar or band M,
secured to the inner face of the sprocket wheel D by means of a screw n passing
through an arm or projection n¹ of the said band. The arm n is bent outward
beyond the edge of the band, as shown in Fig. 15, and is adapted to fit into a
depression p in the sprocket wheel, so as to be flush with the surface thereof. The
engagement of this depression and the projecting arm of the band would alone be
sufficient to keep the sprocket wheel and band in close contact and prevent their
separate rotation; but to render certain the continuous engagement of these parts,
I prefer to employ the additional screw connection n above described. The band M
may be provided on its inner circumference with a suitable friction material n² for
example paper fibre, and is adapted to surround and bear against the peripheral
surface of the rim of the bub B, thereby constituting a friction clamp or lock for
said sprocket wheel and brake mechanism, as and for the purpose hereinafter
described.
At a point on its circumference directly opposite the band projection n', the band
clamp is split or opened and is there provided with two lugs 9, 9, which are joined

page_text: by an adjusting and retaining screws. By means of this split formation of the
band and the adjusting and retaining screw for connecting the ends of said band, it
will be seen that the pressure of the said clamp upon the hub can be adjusted to
any desired degree.
When the sprocket wheel D and brake disc F are locked together in their
normal condition, the frictional resistance between the friction clamp M and the
hub prevents any accidental operation of these parts due to slight and unintentional
back pressure on the driving means, and holds them in this position until sufficient.
reverse pressure on the driving means, caused by the exertion of considerable force,
is brought to bear to overcome such resistance. In such a construction the
strength of the locking action of the said clamp can be regulated to accommolate
the style of vehicle employed and the character of the route to be traversed, and
in the case of a bicycle, can be adjusted to the strength and skill of the rider.
This special construction of locking device (Figs. 15 and 16) in brake apparatus
of the kind referred to, is not herein claimed as forming part of my present
invention as I intend to obtain separate Letters Patent in respect thereof and is
only herein described in order to show the best way now known to me of carrying
my invention into practical effect.
It will be seen that in each of the arrangements herein before describe the
action of the brake is entirely automatic, being controlled by and corresponding to
the pressure exerted by the rider in checking the forward movement of the wheel
in back-pedalling.
It will be obvious that brake apparatus according to my invention may be applied
in connection with the sprocket wheel D' on the pedal or main driving shaft D2,
the fixed friction disc H being then carried by the lower bracket bearing D³ and
the brake disc being located between it and the sprocket wheel D'. The brake
dise is arranged to slide laterally on a collar that is fast to the pedal shaft and is
provided with raised lugs to cause the brake disc to rotate with it. The sprocket
wheel is mounted loose on the shaft between the crank and the collar and is formed
with teeth to engage with similar teeth on the movable brake disc through which
it is rotated from the pedal shaft. This arrangement however is not so advantageous
as that hereinbefore described as should the chain break no braking action can be
exerted upon the machine.
The parts of the brake-mechanism are made to fit closely together, so that dust
and dirt are excluded.
In my invention I have made a brake for bicycles and similar vehicles, which,
while being powerful in its operation, and practically automatic in its application,
yet is so constructed that it will not, by any mischance, be applied when a braking
effect is not desired. To this end, in making a brake applied by the reverse power
of the pedals, I have so constructed it that a given definite amount of reverse
power must be applied before any braking effect will take place. In riding a
bicycle, the rider allows the ascending pedal to carry his foot and leg up with it.
The result in ordinary riding on the level, is that the relative pressure is frequently
greater on the ascending thau on the descending pedal, hence without this arrange-
ment of locking out of action, the brake would be frequently applied when not
desired. As the habits of different riders vary as to the amount of backward
pressure they unconsciously exert, by my arrangement any desired amount of lock
resistance can be applied to suit the requirement of the rider.
Also, I have so constructed my brake that the moment it is put into operation,
it remains locked in operation and so as to exert the same amount of brake force,
until it is released by the rider propelling the bicycle forward again. It frequently
happens that in a sudden emergency the cyclist, especially if a novice, involuntarily
presses backwards so violently on the pedals that his feet fly from them, but in my
brake the amount of retarding power thereby brought into action, remains constant,
entirely independent of the feet of the rider. That this is an essential feature of a
back-pedalling brake will be understood when it is remembered that frequently
when descending steep hills on bicycles, the chain, owing to its not being properly

page_text: adjusted, has mounted the cogs and become broken, or a stick or stone has been
flicked into the chain from the ground, breaking the chain and leaving the rider
helpless so far as any power on his part to retard the speed of his bicycle through
the pedals is concerned. But by my construction, the consequent jerk upon the
chain as it mounts the cogs, or when engaged with a stick or stone between it and
the cogs, powerfully applies the brake which remains in operation entirely
independent of the further integrity of the chain.
As I produce my braking effect by moving a disc or its equivalent laterally and
engaging it at right angles with a friction surface, the braking effect is always in
proportion to the amount of pressure with which the discs are pressed together,
and as the opposing faces are parallel, there is no tendency, as in a band brake, for
the surfaces to become firmly engaged and locked.
A band brake, operating, as it does, on the rope and capstan principle, becomes
a brake up to a certain point, beyond which it will lock or seize, and thus become
a dangerous form of brake, especially should this locking or seizing occur on steep
or dangerous hills, where it is most likely to so act, owing to the great braking
power there needed.
Efforts have heretofore been made to obtain a back pedalling brake for bicycles
and similar vehicles but the constructions proposed have involved various
disadvantages. In some cases the rider's feet come to rest as soon as the forward
pressure is released, and the tricycle runs forward without any back pedalling
power whatever, or again the back pressure must be continued on the pedals to
keep the brake in operation. In most cases the brake would constantly go into
operation through the accidental operation of the pedalling of the rider when
riding over uneven surfaces. In some cases as the power applied to the brake
must be constantly produced by the foot of the rider, this power will vary during
each revolution, being greatest when the pedal is at the half stroke, and being almost
entirely lost at the end of the stroke, thus giving a very jerking motion to the
brake effect. Also when constant backward pressure is required to keep the brake
in operation, should the rider fail to catch the pedals with his feet and get his feet
firmly on them, no braking effect can be produced. Thus, at a time of greatest
danger, as on a very steep part of a hill, the rider might be left helpless. In my
device, however, as the backward pressure, from whatever cause, sets the brake
with a proportionate amount of resistance, the simple holding of the sole of the
boot in the path of the revolving pedal, will cause the pedal to act as a hammer
against the boot and the brake to be powerfully driven on in this way, so that in
like emergency, the very effort made by the rider to regain his pedals, will set his
brake in operation and check his speed.
Ordinary brakes applied to the tires of bicycles produce rapid injury to their
wearing surfaces, as a rubber tire, especially when covered with flint or other hard
matter from a damp road, is rapidly destroyed by the frictional pressure thereon
caused by a spoon brake. Any powerful braking effect upon the front wheel of a
bicycle, if suddenly applied, is very liable to throw the rider, as the braking
effect in front acts as an obstacle over which he is inclined to pitch. By applying
the brake to the rear wheel below and behind the rider, as in the arrangements
hereinbefore described, the brake produces a dragging effect only. Hence it can
be applied with sufficient power to drag the wheel on the ground without any
tendency to throw the rider. In sudden emergencies, which frequently occur when
riding through thick traffic, my brake is thrown into instant and powerful operation
by the instinctive retarding effort of the rider, who; on such occasions, frequently
entirely forgets to apply a hand brake.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. Brake mechanism for bicycles and other vehicles arranged and operating
substantially as herein before descrihod

page_text: 2. Brake mechanism for bicycles and other vehicles arranged so that upon the
exertion of a definite amount of reversing force by back pedalling or its equivalent
the brake is applied and remains applied without further effort until power is
exerted in the forward direction, substantially as described.
3. In brake mechanism for bicycles and other vehicles in which the brake is
applied by hack pedalling or its equivalent, arranging the parts so that forward
pedalling or its equivalent positively withdraws the brake and keeps it locked out
of action, substantially as described.
4. In brake mechanism for bicycles and other vehicles the combination of two
parts carrying teeth with inclined surfaces which operate together so that the
brake is applied by the differential movement of the parts in one direction and
positively withdrawn by the differential movement of the parts in the other
direction, substantially as described.
5. The combination of the 'sprocket wheel or its equivalent with means for
securing that its differential movement relatively to the hub shall take place only
upon the application of a definite force, substantially as described.
engaging
6. The particular arrangement of sprocket wheel furnished with pin
with spring G upon the hub operating as and for the purposes mentioned in the
last claim, substantially as described.
7. Brake. mechanism for bicycles constructed arranged and operating sub-
stantially as hereinbefore described with reference to Figs. 1 to 7.
8. Brake mechanism for bicycles constructed arranged and operating sub-
stantially as hereinbefore described with reference to Figs. 8 to 11.
Dated this 20th day of March 1907
P. E. DOOLITTLE.
W. Lloyd Wise, C.P.A.,
46 Lincoln's Inn Fields, W.C., Applicant's Agent.
P. E. DOOLITTLE.
W. Lloyd Wise, C.P.A.,
46 Lincoln's Inn Fields, W.C., Applicant's Agent.