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

page_text: PROVISIONAL SPECIFICATION.
Improvements in Driving Gear for Cycles and the like.
จ
We, JOHN WESTROPP BRERETON, of Ladywell, Athlone, West Meath, Ireland,
Mechanical 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 particularly for cycles but is applicable
to other mechanisms, as for example, self-propelled vehicles.
We will describe the invention as applied to a cycle. The crank axle is
carried inside a sleeve upon one end of which is fixed the chain wheel, and upon
the other the hollow drum, the outside of which may be used to accommodate
a baud brake if desired; the sleeve runs in ball bearings in the bracket or
portion of the frame which carries it. Inside the drum is a coiled spring like a
clock spring, the outer end of which is secured to the drum in any suitable
manner, while the inner end is secured to the crank axle, a desirable way of
doing this being to form the inmost coil of the spring as a complete ring by"
rivetting or otherwise securing the end, the ring being if necessary strengthened.
by another complete ring applied to it and the crank axle provided with a
suitable number of inclined pockets between which and the ring of the spring
are rollers, the whole forming a clutch acting upon a well-known principle.
When the crank axle is driven in the forward direction the clutch engages and
acts upon the spring until the power is sufficient to propel the cycle. When the.
crank axle is held by the rider using the pedals as foot rests, the sprocket wheel.
carrying the sleeve forward i.e., (over-running the pedal axle) would unwind the r
spring over much and therefore break it, were it not for the clutch ceasing to act;
thereby leaving the spring free so far as the axle is concerned.
A clutch engagement mechanism is employed in connection with the chain
wheel in the following manner:-
The end of the before-mentioned sleeve which may be considered as a portion.j
of the chain wheel carries inside it an eccentric sheave which is bored eccentri
cally and receives another eccentric fixed upon the crank axle. The throws of
these two eccentrics are the same, so that when they lie with the throw of the
inner one at the opposite pole to that of the outer one, the crank./
axle lies concentrically with the sleeve, and can turn therein. The "
inner eccentric has a peripheral slot in which is a stop upon the outer..
eccentric so that when the inner eccentric which is fixed upon the crank axle
bears against the stop it carries the outer eccentric round with it, concentrically...
with the sleeve and acts upon the spring on the other end of the axle, and the
machine can be propelled forwards. When the forward rotation of the crank
axle is opposed by back pedalling, or by the action of the inner end of spring
acting to bring the pedals backwards when the power of foot is weak at the dead
centre, the stop in the outer eccentric moves in the slot in the inner eccentric,:,
thus allowing the two eccentrics to become out of line with each other, and thus,
eccentric to the sleeve. When the spring is being acted on the eccentrics are in

page_text: alignment, and run free in the sleeve, any alteration of the positions of the
respective parts is only effected by intentional back-pedalling.
Ball bearings may be employed between the crank axle and the sleeve if
desiřed.
Preferably the apparatus should comprise a short lever shaped to be engaged by
the pocket clutch and also by the pin by which the outer end of the spring is
ordinarily retained; in the event of breakage of the spring this lever can be
substituted therefor, so as to be coupled by the clutch with the spring box to take
the place of the spring.
The outer eccentric of the clutch is preferably loosely connected with the cover
of the clutch box by a pin and slot connection or otherwise in order that the
tendency of the cover to rotate about its centre may keep the eccentric sleeve from
moving with the eccentric by friction instead of allowing the eccentric to move
backwards without it in order that the clutch may act.
Dated this 29th day of January 1897.
BOULT & WADE,
Agents for the Applicant.
Improvements in Driving Gear for Cycles and the like.
We, JOHN WESTROPP BRERETON, of Ladywell, Athlone, West Meath, Ireland,
Mechanical Engineer, and WILLIAM WESTROPP BRERETON, of Prospect Hill,
Galway, Ireland, Surgeon, 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 particularly for cycles but is applicable
to other mechanism, as for example, self-propelled vehicles.
The crank axle is
We will describe the invention as applied to a cycle.
carried inside a sleeve upon one end of which is fixed the chain wheel, and upon
the other the hollow drum, the outside of which may be used to accommodate
a band brake if desired; the sleeve runs in ball bearings in the bracket or
"portion of the frame which carries it. Inside the drum is a coiled spring like a
clock spring, the outer end of which is secured to the drum in any suitable
manner, while the inner end is secured to the crank axle, a desirable way of
doing this being to form the inmost coil of the spring as a complete ring by
rivetting or otherwise securing the end, the ring being, if necessary, strengthened
by another complete ring applied to it and the crank axle provided with a
suitable number of inclined pockets between which and the ring of the spring
are rollers, the whole forming a clutch acting upon a well-known principle.
When the crank axle is driven in the forward direction, the clutch engages and
acts upon the spring until the power is sufficient to propel the cycle. When the
crank axle is held by the rider using the pedals as foot rests, the sprocket wheel
carrying the sleeve forward i.e., (over-running the pedal axle) would unwind the
spring over much and therefore break it, were it not for the clutch ceasing to act,
thereby leaving the spring free, so far as the axle is concerned.
A clutch engagement mechanism is employed in connection with the chain
wheel in the following manner:-
The end of the before-mentioned sleeve which may be considered as a portion
of the chain wheel, carries inside it an eccentric sheave, which is bored eccentri-
cally and receives another eccentric fixed upon the crank axle. The throws of
these two eccentrics are the same, so that when they lie with the throw of the
inner one at the opposite pole to that of the outer one, the crank

page_text: axle lies concentrically with the sleeve, and can turn therein. The
inner eccentric has a peripheral slot in which is a stop upon the outer
eccentric, so that when the inner eccentric, which is fixed upon the crank axle,
bears against the stop, it carries the outer eccentric round with it, concentrically
with the sleeve, and acts upon the spring on the other end of the axle, and the
machine can be propelled forwards. When the forward rotation of the crank
axle is opposed by back pedalling, or by the action of the inner end
of the spring, acting to bring the pedals backwards, when the effective
turning movement of the foot is small
near the dead centres, the
stop in the outer eccentric moves in the slot in the inner eccentric,
thus allowing the two eccentrics to become out of line with each other, and thus
eccentric to the sleeve. When the spring is being acted on, the eccentrics are in
alignment, and run free in the sleeve. Any alteration of the positions of the
respective parts is only effected by intentional back-pedalling.
Ball bearings may be employed between the crank axle and the sleeve if
desired.
The outer eccentric of the clutch is preferably loosely connected with the cover
of the clutch box by a pin and slot connection or otherwise, in order that the
tendency of the cover to rotate about its centre may keep the eccentric sleeve from
moving with the eccentric by friction instead of allowing the eccentric to move
backwards without it in order that the clutch may act.
The invention will be best understood by reference to the accompanying
drawings, in which
Figure 1 is a section on the line 1-1 of Figures 2 and 3 of the bottom bracket
of a cycle having our improved driving gear 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 view of a device hereinafter more particularly described.
Figures 5 and 6 illustrate to a larger scale than the rest of the drawings an
alternative form of clutch mechanism to provide for back-pedalling.
Like letters indicate like parts throughout the drawings.
The crank axle A is mounted in a sleeve B on ball or cone bearings B. The
sleeve itself is mounted on ball bearings B2 in the bottom bracket C of the cycle.
On one end of the sleeve B is rigidly secured the chain wheel 1) formed with a
central chamber or hollow boss D', and on the other side is fixed an arm E
through which is transmitted the power necessary for rotating the chain wheel D.
At or near the outer end of the arm E is fixed the stud or pin E which projects
into a circular drum or casing 1' fixed to the said arm and containing a coil
spring G of which the outer end is attached to the pin E and the inner end is
secured to an inexpansible or rigid ring G¹: this ring G¹ is not attached to any
other part of the mechanism, although as hereinafter described, it becomes
temporarily locked to the other parts by means of a clutch.
Instead of providing a separate ring G to which to secure the spring G as just
described the spring itself may be arranged so that its inner turn constitutes the
ring, this may be done by rivetting or otherwise securing its inner end to the
next adjacent convolution of the spring.
Within the ring G₁ we provide a disc G2 rigidly secured to the crank axle A
and provided in its periphery with a series of recesses or pockets G3 each receiving
a roller G. Curved surfaces of the disc D2 form the bottoms of the pockets G³
and are not concentric with the crank axle A: they thus constitute in a manner
well understood and well known, cams or gripping surfaces between which and
the inner surface of the ring G₁ the rollers G become jammed when the crank
axle A is rotated in the direction indicated by the arrow in Figure 2, that is to say:
the direction in which the axle A must be turned for propelling the cycle forward.
By the foregoing arrangement the cyclist rotates the sleeve B and the chain
wheel D through the spring G which may consist of one or two coils only, and we
are enabled to use a lower gear than would be otherwise desirable, which gives an

page_text: advantage in mounting hills, and when riding against the wind, while allowing
as high a speed to be attained on the flat as if a higher gear were used.
To prevent the backlash of the pedals and secure their being brought over at
the end of each stroke from the dead centre and also to enable the cyclist to retard.
the progress of the cycle by back-pedalling (which owing to the previously.
explained action of the disc G3 and rollers G is not possible through the medium
of the spring G) we secure on the crank axle A within the hollow boss D2 two
similar eccentric sheaves J and J¹, whose centres are diametrically opposite each
other, and preferably perpendicular to the line of the pedal cranks H¹. On each
of these eccentrics is mounted an eccentric dog or strap, that is to say a dog K
on the sheave J and a dog K¹ on the sheave J₁. The eccentricity of each dog is
opposed diametrically to the eccentricity of its own sheave and these dogs are
therefore adapted to be forced outwards into a frictional engagement with the
surrounding cylindrical interior of the boss D¹ when by the action of back
pedalling the eccentric sheaves J and J and dogs K and K are moved relatively
to each other in the direction indicated by arrows on those parts in Figure 3.
The outer side of the hollow boss D₁ is closed by a "floating" disc or cover Da
which fits loosely round the crank axle A and loosely at its edges in a rebate on
the boss D', contact with D1 being prevented by the boss of the disc D2 lightly
touching the face of the outer eccentric J and thus having clearance from the
rebate.
Upon this disc D2 are provided two studs or pins d and d¹ which project respec-
tively into slots k and ¹ formed in the dogs K and K. There is sufficient
clearance between each dog and the boss D¹ to ensure that at the overtaking of
the cranks by the boss it shall not cause contact so long as the eccentricity of the
dog is opposed to that of the eccentric sheave. Should the cyclist desire to stop
pedalling for a short time but continue to go forward by impetus it is only
necessary to keep the feet on the pedals using them as foot rests. In like manner
the pedals can be used as foot rests while running down any hill and while so doing
there is little liability to skid since the cyclist retains the natural position of the
feet on the pedals which position also allows the rider to immediately back pedal
should the pace become undesirably high by failure of the brake to act sufficiently
or from any other cause.
The act of back pedalling causes relative motion between the eccentric sheaves
and the dogs, owing to the inertia of the latter together with that of the disc D³
to which they are connected by the pins d and d and which rotates about a
different axis from that about which the dogs rotate. This relative motion
thrusts the dogs outwards from the centre and results in the frictional engage-
ment of the dogs with the internal periphery of the chain wheel boss.
The disc D2 with the pins d and d serves to couple and keep at the same
angular distance apart, and to steady the two dogs K K in such a manner as to
allow the eccentrics to move relatively to them through the small angle necessary
for engaging them with the interior of the boss D¹ and disengaging them there-
from in the manner hereinbefore described.
As shown in Figure 4 each of the sheaves J and J¹ is provided with a fillet L
which fits into a groove in the surrounding strap or dog, to retain each strap
upon its ecentric which is free to receive motion through an angle relatively to its
dog or vice versa until the said dog is forced into or drawn out of frictional
contact with the inner cylindrical surface of the boss D¹.
In Figure 4 is shown a separate view of a dog and eccentric as seen when
looking in the direction of the arrow 4 of Figure 1. The arrow on the sheave J
indicates the direction of forward rotation of the axle when it is desired to drive
through the spring G. The reverse direction is the direction in which force for
back pedalling has to be exerted.
The details of construction such as the bolts the lugs through which they
pass, and distance pieces ², are ommitted from Figure 1 for the sake of clearness.
The distance piece ² extends into a gap L' in the fillet L and thus acts as a stop

page_text: to prevent relative movement of the dog K and sheave J and to carry the former
round concentrically with the axis during forward driving of the cycle.
When however it is desired to back pedal relative movement can occur in the
reverse direction until the stop comes into contact with the other limit formed
by the fillet L of the gap L'.
Before however this limit is reached the dog K is in frictional engagement with
the interior of the chain wheel boss D¹.
Although we prefer to use two eccentrics and two dogs in order to avoid bending
stress on the crank axle and a one sided thrust on the chain wheel we may use
only one eccentric and one dog in which case we balance 'the weight of the dog
by attaching a counter-weight either to the strap or to the disc and diametrically
opposite to the dog.
The alternative form of clutch illustrated in Figures 5 and 6, differs from that
already described principally in the absence of the stop and the gap L¹ in the
fillet L, and in the shape of the projection which comes into frictional engagement
with the internal periphery of the chain wheel boss.
In this device, in addition to the provision made for back pedalling the edge
of the dog K2 has a forward extension 5 through which the chain-wheel can be
positively driven from the crank axle without the intervention of the spring G.
The method of construction is simple and easily understood by reference to the
drawings. We do not confine ourselves to this mode of construction however.
The action is as follows:-
When riding up hill say, after the spring G has been compressed a certain
small amount, the edge of the dog will come into engagement with the boss of the
chain wheel, owing in the absence of the stop to the relative movement of the
dog K2 and eccentric sheave J2. Disengagemnt of this edge can be effected by a
slight back pressure on the pedals after which the dog will be carried round by
friction on the sheave concentrically with the axle. Back pedalling is effected
as before. At is shown a hole for the insertion of a pin carried by the disc 1)².
To prevent the oil from flowing from the ball-bearings B₁ into the hollow boss D₁
which might prevent the prompt engagement of the dogs K K' we prefer to form
an annular channel N between the eccentrics J¹ and the ball-cone A¹ adjacent to
it and to provide a ring or collar N¹ being a flange upon another ring N³ fitted in
a recess in the hollow boss D¹ and provided with holes n to enable it to be screwed
into position by a suitable pin-spanner.
When the cyclist meets or runs over an obstacle such as a stone or the like the
sudden resistance to rotation which would otherwise be presented to the pedals
with consequent shock to the cyclist and strain to the cycle is absorbed by the
spring. It is obvious that when the cyclist gives a heavy thrust on the pedal
the work not used up to increase the speed of the cycle is stored in the spring and
given out to increase the speed of the chain-wheel when the rider again presses
the pedal forward with sufficient force to resist the back pressure of the spring,
thus the chain wheel D over-runs the axle A for the greater portion of each
stroke causing the bicycle to travel at a higher speed than that represented by
the number of revolutions of the pedals.
It is to be understood that the term
back-pedalling "used in this specification
does not imply actual rotation of the crank axle in a backward direction, except to
such an extent as is necessary to cause engagement of the dogs with the boss of
the chain wheel, and to take up the slack of the driving chain; beyond this the
rotation of the axle occurs in a forward direction but exerts a retarding force
during the operation of back-pedalling.
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. A driving gear in which the power is transmitted through a spring, but
the gear will allow of "back-pedalling."
;

page_text: .
2. In a driving gear for cycles and the like the combination with a spring G
connected at one end with the sprocket wheel of a clutch such as that formed by
the ring G cam G2 secured to the crank axle and rollers G substantially as and
for the purpose described or illustrated in the accompanying drawings.
3. In a driving gear for cycles and the like the combination with a spring G
and driving wheel 1 of a sleeve B allowing the spring to be placed remotely as
regards the wheel I substantially as described and illustrated in the accompanying
drawings.
4. In a driving gear for cycles and the like the combination with a spring
affording means for storing work of a clutch which will drive positively when the
force transmitted by the spring is less than the resistance to motion of the
cycles and allow the driven part to over-run the driving axle when required
substantially as described.
5. The combination and arrangement of parts constituting the complete driving
gear for cycles and the like substantially as described and illustrated in the
accompanying drawings.
Dad 5th do
£ Octal 180
BOULT & WADE,
Agents for the Applicants.