Improvements in Driving Gear for Cycles.
Year: 1896

page_text: Improvements in Driving Gear for Cycles.
We ALBERT EDWARD COTTON of 130 Gordon Road Machinist, and MORITZ
ROTHSCHILD of 391 Queens Road, Lace Merchant, both in the Town and County
of the Town of Nottingham do hereby declare the nature of this invention to be
as follows:-
Our invention relates to chain driving wheels, which are constructed to act
automatically as a lever, and chain wheel, combined, wherchy, increased speed is
obtained, with considerably less pressure required, from the foot on the driving
pedal consequently, the rider of the cycle, has, less exertion to travel any distance,
than with the ordinary chain wheel.
For the purpose of our invention we make a flange on the hub of the wheel,
large enough in circumference, to carry a small stud axle, and truck, or a bracket
can be secured by screws or rivets to the flange of the hub to increase the
circumference of the flange, on one side, only, as required to carry the stud axle
and truck.
The axle of the driving wheel is made long enough to carry a grooved wheel or
sleeve, with a flange on each side to carry three small axles, and trucks or rollers,
or if preferred ball bearings can be used, the hole, for the axle carrying this
grooved wheel or sleeve being made inch, more or less out of centre, as required,
gives an excentric movement to the chain wheel.
A cam lever, with a slot or groove, to act on the truck carried by the axle
secured to the flange on the hub of the driving wheel, is secured to or cast on to
the toothed chain wheel and sleeved on to the grooved wheel carried by the axle
of the driving wheel, when the chain acts on the toothed wheel, the cam lever.
revolves the driving wheel, and at the same time increases the radius, thereby,
increasing the speed of the cycle.
We do not confine ourselves to fix the appliance to the driving wheel only as it
can be used on the toothed wheel on the axle carrying the pedals, or on the front
wheel, as desired.
ALBERT EDWARD COTTON.
Improvements in Driving Gear for Cycles.
We ALBERT EDWARD COTTON, of 130 Gordon Road, Machinist, and
MORITZ ROTHSCHILD, of 39 Queens Road Lace Merchant both in the Town
and County of the Town of Nottingham, 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, reference being had
to the accompanying drawings and to the letters and figures marked thereon, that
is to say:-
This invention relates to improvements in driving gear for cycles, and is designed

page_text: to enable the driving power to be applied in a more effectual manner than
heretofore, and with a greater mechanical purchase, leverage, or advantage to the
driving wheel, or wheels, of the machine, so that less pressure from the foot is
required on the pedals, and the rider has less exertion than with the ordinary chain
driving arrangement.
To this end one of the chain or sprocket wheels is arranged in such a way that,
whilst always keeping the same position with regard to the frame of the machine,
it rotates eccentrically with regard to the wheel axle to which it is applied.
By causing the pull or strain of the chain to act at the point of greatest eccentricity,
the aforesaid purchase or leverage is obtained.
In carrying out the invention, the eccentrically arranged sprocket or chain wheel
is made in the form of a ring or band, the centre part being cut away, and is
mounted by a suitable antifriction bearing, or bearings, upon the circumference of
a fixed eccentric secured either to the driving wheel axle or to a convenient part of
the frame. A suitable connection, on the principle of a pin and slot arrangement,
is provided to connect the sprocket or chain wheel with the driving wheel, or with
the pedals, according as it is mounted upon the axle of the driving wheel, or on the
pedal axle.
And in order that the invention may be readily understood, reference will be
made to the accompanying drawings which illustrate its application to the rear
wheel of a rear driving safety bicycle.
Fig. 1 is a side view of the central or hub portion of such rear wheel.
Fig. 2 is a view taken at right angles to Fig. 1, of the said hub portion, one
half being shown in elevation, and the other half in section.
Figs. 3 and 4 are respectively a side and an edge view of the fixed eccentric
carrying the said sprocket wheel.
Figs. 5 and 6 are elevations of opposite sides of the said sprocket wheel, and
Fig. 7 is an edge view thereof.
Figs. 8 and 9 are respectively a side and an edge view of the hub of the driving
wheel adjacent to the sprocket wheel.
a is the eccentric sprocket wheel which, as will be seen in Figs. 2, 5 and 6, has
two internal ball races al and is provided with an arm or projection a³ in which is
formed a recess a³. This recess corresponds to the slot in a pin and slot connection,
and may have a liner a', of hard steel, to prevent undue wear. b is the fixed
eccentric round which the wheel z rotates. This eccentric is formed in two parts,
connected by screws, and each part is provided with a groove or ball race b¹ corre-
sponding to the races a'. It has an eccentrically disposed hole or perforation b
for the passage of the driving wheel axle c, and it is prevented from turning on this
axle by a projection whose upper and lower sides 6 are flattened, and which,
when the parts are assembled, fits in the clip or forked extension 6 of the
frame.
Rigidly connected, or formed in one with the driving wheel hub, is a disc c
provided with an arm or projection c² corresponding to the aforesaid arm or
projection a² and having a stud or pin c on which is mounted a truck or roller c
adapted to enter the recess a³, and forming the equivalent of the pin in a pin and
slot connection. It will be seen that, by this arrangement, the two arms and their
connected parts are bound to turn in unison, and that the lost motion in the recess a
compensates for their motion round different centres.
The part d is an ordinary arrangement for tightening up the chain by drawing
back the rear wheel, and forms no part of the invention.
The action of the improved driving gear is as follows:-
The pull of the chain is exerted on the sprocket wheel at the end of the longest
radius of eccentricity, and consequently has an increased purchase, or leverage,
beyond what it would have if the wheel were mounted centrally, the degree of
advantage or purchase being the ratio which the longest radius of eccentricity
bears to the true radius of the wheel. Furthermore, when the lever a² is at its
dead centre, one or other of the pedals is a quarter of a revolution in advance

page_text: of it, and thus the extra effort required to overcome dead centres is no longer
wasted.
The invention may be applied to front, as well as to rear driving cycles.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :-
1. In chain driving gear for cycles, the method of increasing the purchase, which
consists in mounting one or other of the chain or sprocket wheels eccentrically, and
causing the chain to act at the end of the longest radius of eccentricity.
2. A chain driving gear for cycles having one of the chain or sprocket wheels
mounted eccentrically with regard to the part with which it is in driving connection,
and having its longest radius of eccentricity terminating at the point where the
pull of the chain is applied, substantially as described.
3. In chain driving gear for cycles, the combination of a chain or sprocket wheel,
a fixed eccentric carrying said wheel and having its longest radius towards the
point on which the pull of the chain is exerted, and means for causing the sprocket
wheel and the driving wheel to rotate together, substantially as described.
4. In chain driving gear for cycles, the combination of a chain or sprocket wheel,
an eccentric carrying said wheel and having its longest radius at right angles to
the line of pull of the chain, an antifriction bearing between said sprocket wheel and
eccentric, and a connection on the pin and slot principle between said sprocket
wheel and the driving wheel, or wheels, or the crank, of the cycle, substantially as
described.
5. In chain driving gear for cycles, the combination of an eccentrically mounted
sprocket wheel, an arm or projection secured to said sprocket wheel, and having a
recess in one side thereof, and a corresponding arm or projection on the hub of the
driving wheel having a truck adapted to enter and work in such recess, sub-.
stantially as described.
6. In chain driving gear for cycles, the combination of a driving wheel, a fixed
eccentric mounted on the axle of said driving wheel with its longest radius at right
angles to the pull of the driving chain, a spokeless sprocket wheel encircling said
eccentric, and separated therefrom by ball bearings, an arm or projection ou said
sprocket wheel, a corresponding arm or projection on said driving wheel, and a
connection on the pin and slot principle between said arms, substantially as
described.
7. The improvements in driving gear for cycles, substantially as shown and
described.