Improvements in or relating to Driving Gear for Cycles and the like.
Year: 1897

page_text: Date of Application, 3rd Nov., 1897
Completo Soccification Loft 3rd Aug 1898 Accented 3rd Nov. 1898
PROVISIONAL SPECIFICATION.
Improvements in or relating to Driving Gear for Cycles and the like.
We, JOHN WESTROPP BRERETON, of Ladywell, Athlone, West Meath, Ireland,
Engineer, and WILLIAM WESTROPP BRERETON, of Prospect Hill, Galway, Ireland,
Surgeon, do hereby declare the nature of this invention to be as follows:-
This invention relates to driving gear for cycles or starting-gear for autocars
and the like, its object being to provide an improved clutch through which the
progress of a cycle for instance, may be retarded by acting upon the crank axle as
in the operation known as "back-pedalling," and which will also allow the rotation
of the crank axle to be stopped if desired while the machine is running forwards.
The clutch is intended for use in conjunction with a second clutch or equivalent
mechanism which will transmits driving power to the machine and yet allow of
stoppage of the rotation of the pedal shaft or crank axle. It may for example be
constructed with a ratchet wheel and pawl as is commonly done. The improved
clutch according to this invention consists essentially of a cam-like member con-
nected and rotating with the crank axle of the cycle and placed within a drum
formed conveniently by a hollow boss on the chain-wheel. The cam-like member
is itself free from contact with the circumferential wall of the drum but can he
brought into frictional engagement therewith by means of one or more rollers or
other devices which become jammed between an eccentric edge of the cam and the
circumferential wall of the drum.
When the cycle is running with the pedal shaft stopped the rollers or wedge.
or wedges are carried by pockets or projections in or upon the cam in an inoperative
position, the cam being specially shaped for this purpose.
Improvements in or relating to Driving Gear for Cycles and the like.
We, JOHN WESTROPP BRERETON, Mechanical Engineer, of Ladywell, Athlone,
West-Meath, and WILLIAM WESTROPP BRERETON, Surgeon, of Prospect Hill,
Galway, both in Ireland, 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 driving gear for cycles or starting gear for autocars
Price El

page_text: and the like, its object being to provide an improved clutch through which the
progress of a cycle for instance, may be retarded by acting upon the crank axle as
in the operation known as back-pedalling" and which will also allow the rotation
of the crank axle to be stopped if desired without affecting the forward movement
of the machine.
The clutch is intended for use in conjunction with a second clutch or equivalent
mechanism which will transmit driving power to the machine and yet allow of
stoppage of the pedal shaft or crank axle while the machine continues its forward
It may for example comprise in part such an arrangement as that
described in the Specification of Letters Patent No. 2460 granted to us and dated
29th January 1897.
movement.
The improved clutch according to this invention consists essentially of a cam-
like member connected and rotating with the crank axle of the cycle and placed
within a drum formed conveniently either by a hollow boss on the chain-wheel or
by a circular box which may be mounted on a sleeve and placed upon the side of
the bottom bracket remote from the chain wheel. The cam-like member is itself
free from contact with the circumferential wall of the drum but can be brought
into frictional engagement therewith by means of two rollers or balls which become
jammed between the eccentric edges of the cam-like member and the inner circum-
ferential wall of the drum.
When the cycle is running with the pedal shaft stopped the rollers are carried
in an inoperative position by specially shaped pockets or projections in or upon
the cam.
The invention will be clearly understood by reference to the accompanying draw-
ings, in which
Figure 1 is a central vertical section through the bottom bracket of a cycle having
an improved clutch according to one construction of this invention fitted thereto.
Figures 2 and 3 are sections taken respectively on the lines 2-2 and 3-3 of
Figure 1.
Figure 4 is a vertical central section of a modified arrangement of this invention
as fitted to the bottom bracket of a cycle.
Figure 5 is a section on the line 5-5 of Figure 4.
Figure 6 is a similar view showing the clutch in a different position.
Like letters indicate like parts throughout the drawings.
The improved clutch illustrated by way of example in Figures 1 and 2 comprises
a drum A which forms part of a boss on the chain-wheel A¹ of a bicycle, and a cam-
like member B which is attached to the crank axle C. The drum A is provided
with a cover A2. The cam-like member B which forms the principal feature of
this invention is provided with eccentric surfaces B¹, pockets B2 and guides B³
which operate as hereinafter described. The member B is free to revolve within
the drum A, except when brought into frictional engagement with it through
rollers or balls D by means of the two eccentric surfaces B. The recesses or
pockets B2 are of such depth and shape as to enable them to retain the rollers or
balls D in an inoperative position except when the cam piece B is approximately
in the position indicated in Figure 5.
One wall of each of the pockets B2 is extended in the form of a guide or finger B³
which curves in the direction of rotation but does not project so far as to come into
contact with the inner surface of the drum A. The chain wheel A with the
drum A is carried upon a hollow shaft E mounted on ball bearings within E¹ the
bottom bracket F of the cycle; the crank shaft C passes through the hollow shaft E
and runs on ball bearings E2 within it. Any form of clutch may be used to trans-
mit power for forward driving from the axle C to the sleeve E provided such clutch
will allow the axle C to be held stationary while the hollow shaft E continues to
rotate. The driving clutch referred to in the specification above cited is however
preferably used and is illustrated in Figures 1, 3 and 4 in conjunction with the
clutch forming the subject of the present invention. In these figures G is the well
known cam device and is fastened to the crank axle C.

page_text: the
When the axle is rotated in the direction indicated by the arrow, Figure
cam G is brought into frictional engagement by means of rollers or balls G', with
a free ring G2 from which the driving power is transmitted through the medium of
a spring G³, to an arm G+ fast upon the hollow shaft E. The object of the spring G³
is to avoid shock when the clutch comes into action and throws the axle C into
engagement with the hollow shaft E. The spring G³ is attached to one end to
the arm G by a stud G5 the other end being rivetted to the ring G³ or if desired
rivetted back upon itself to form the ring G. The clutch parts may be covered
by a protecting box or casing Gº.
The operation of the clutch is as follows:-
When the rider is pedalling forward at a moderate speed, the driving is effected
through the cam G and spring G³; the member B does not under these conditions
engage with the drum A, for although the rollers or balls D drop out of the
pockets B2 when the cranks are at or about the dead centre, (as indicated by the
line - in Figure 6) they are immediately caught by the guides or fingers B3
and return to the pockets B³.
Both clutches it must be understood permit the machine to over-run the crank-
axle C. Should the rider, in ascending a hill for instance, have difficulty in pass-
ing over the dead centre, the ball or roller D in the bottom position at that moment
having fallen out of its pocket B2 will, jamm between the drum A and the adjacent
eccentric surface B₁ of the member B (Figure 5). The chain wheel A¹ being thus
momentarily operatively connected to the crank-axle C, carries the pedal over the
dead centre. When the cranks come into such a position that one of the rollers D
brings the clutch into action, a slight pressure on the forward pedal will
immediately allow the roller to return into pocket and free the pedals once more.
When coasting" the rider may hold his pedals stationary in a horizontal
position as indicated in Figure 2, by the line a a or in almost any position other
than that close to the dead centre, as until the cranks are approximately at their
dead centre, the roller D will remain in the pockets 132, at or about which point the
clutch comes into action when the over-running machine would carry the pedals
round until the rider put a slight forward pressure upon the descending pedal which
would instantly release the gripping roller or ball and leave the crank axle again
free.
66
To give back-pedalling" the rollers or balls D drop out of the pockets as they
arrive at the bottom position and bring the clutch into engagement as already
described, the forward clutch G, G³ etc. being of course inoperative. Both of the
rollers D may sometimes become engaged, when it will be necessary to put a slight
forward pressure upon each pedal as it passes over the dead centre, before they are
again released and the crank axle freed.
To ensure the accurate working of the clutch the ends of the guides or fingers B³
should not project in the direction of rotation beyond a vertical line drawn through
the centre of the roller or ball D when in the lower position shown in Figure 6.
Figure 4 shows a modified arrangement of this invention, the cam G spring G³,
and other parts of the forward driving clutch being mounted in a boss on the chain
wheel A¹ the clutch B being mounted upon the opposite side of the bracket F.
The drum A of the back-pedalling clutch is screwed upon the sleeve E and held by
a lock-nut A3. The arm G is dispensed with the stud G to which one end of the
spring G is attached being fixed direct upon the boss of the chain wheel. It is
of course obvious that the chain wheel with either of the clutches may be mounted
upon either side of the bracket E.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, we declare that what
we claim is:
1. The combination with a driving gear for cycles and the like of a clutch
coming automatically into operation only when the driving cranks are at or about

page_text: the dead centre for the purpose of effecting back-pedalling while permitting over-
running substantially as described.
2. In a clutch mechanism for cycles and the like the combination with a drum
or box such as A and operating rollers D of the cam-like member B provided with
pockets B and guides B3 substantially as and for the purpose described.
3. In a clutch mechanism for cycles and the like the cam-like member B B¹
having pockets 132 and guides B3 substantially as described and illustrated in the
accompanying drawings.
4. The combination and arrangement of parts constituting the complete driving
gear for cycles and the like substantially as described and illustrated in Figures 1,
2 and 3, or Figures 4 and 5 of the accompanying drawings.
1000
BOULT & WADE,
Agents for the Applicants.