Year: 1898

page_text: I, JOSEPH PARSONS, of 22, County Road, Walton, in the City of Liverpool, in the
County of Lancaster, Umbrella Maker, do hereby declare the nature of this invention
to be as follows:-
This invention has reference to improvements in crank mechanism suitable for use
with bicycles and the like whereby a greater leverage is obtained at that part of the
travel of the crank where the power is chiefly applied which, in the case of a bicycle,
is when the pedal is moving in a downward direction, the increased leverage being
obtained without any increase in the length of the crank.
According to one arrangement wherein the improved crank mechanism is applied
to the driving gear of a bicycle I provide two sets of chain wheels with chains one on
each side of the machine, the larger or driving chain wheels being capable of rotating
freely upon the driving axle which in this case is fixed in the crank bracket of the
cycle frame i.e., so that it cannot rotate therein. Upon the outer face of each driving
chain wheel there is fixed a lever or bar extending in a radial direction so that one
end projects beyond the periphery of such wheel for a suitable distance, for example
it may project for a distance equal to half the diameter of said chain wheel. To each
outer end of the aforesaid axle there is fixed an arm arranged to extend in a forward
direction the length of the said arm being in this example approximately equal to the
radius of the chain wheel. At the outer end of each fixed lever there is rotatably
mounted one end of a curved pedal lever carrying an adjustable pedal at its outer
free end and suitably grooved or slotted so as to form a path for a roller carried by a
pin at the outer end of the aforesaid radial lever or bar the said roller being prefer-
ably mounted on an anti-friction bearing. The two pedal levers are arranged at
180° apart. The path of the pedals is eccentric to the driving wheel, the eccentricity
being disposed in a forward direction. The arrangement is such that during the
forward and downward portion of each revolution the pedal is extended considerably
beyond the outer end of the radial bar whereby the leverage is increased.

page_text: Improvements in Crank Mechanism.
I, JOSEPH PARSONS, of 22, County Road, Walton, in the City of Liverpool, in the
County of Lancaster, Umbrella Manufacturer, 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 has reference to improvements in crank mechanism suitable for use
with bicycles and the like whereby a greater leverage is obtained at that part of the
travel of the crank where the power is chiefly applied which, in the case of a bicycle,
is when the pedal is moving in a downward direction, the increased leverage being
obtained without any increase in the length of crank.
In the accompanying illustrative drawings:-
Fig. 1 is a side elevation showing one arrangement of crank mechanism in accor-
dance with this invention applied to the rear driving wheel of a bicycle.
Fig. 2 is a plan partly in section showing one pedal in forward position and the
other in rear position.
Fig. 3 is a partial side view with the pedals in the position shown in Fig. 2.
According to this arrangement I provide two sets of chain wheels 1, 2, with
chains 3, one set on each side of the machine, the larger or driving chain
wheels 1 being capable of rotating freely upon the driving axle 4 which in this case
is fixed in the crank bracket 5 of the cycle frame i.e. so that it cannot rotate
therein. The chain driving wheels 1 are preferably provided with ball bearings 6
and an adjustable screw cone 7. Upon the outer face of each driving chain
wheel 1 there is fixed a lever or bar 8 extending in a radial direction so that
one end projects beyond the periphery of such wheel for a suitable distance
according to the size of the gearing desired. To each outer end of the fixed axle 4
there is fixed an arm 9 arranged to extend for a suitable length in a forward direction.
At the outer end of each fixed arm 9 there is rotatably mounted a pedal lever 10
that may be curved or otherwise, for carrying a pedal 11 near its outer free end and
suitably grooved or slotted so as to form a path for a roller carried by a pin 12 at the
outer end of the radial lever 8, the said roller being preferably mounted on an anti-
friction bearing. The dotted circle A Fig. 1 shows the forwardly disposed eccentric
path of the pedals whilst the dotted circle B indicates the path of the pin at the end
of the lever 8. The pin roller 12 in the driving arm 8 may be at any convenient
distance from the centre of the driving chain wheel 1. The pedal lever 10 which
turns on the fixed pin 13 and slides along the driving pin 12 is forced outwardly on
the down or driving part of the stroke and is brought back towards the centre on the
upward stroke as shown in Fig. 3. The two pedal levers are arranged at 180° apart.
The path of each pedal is eccentric to the corresponding driving wheel, the
eccentricity being disposed in a forward direction by means of the forwardly extending
arms 9 the arrangement being such that during the forward and downward portion
of each revolution the pedal lever is extended considerably beyond the periphery of
the driving wheels whereby the leverage is increased.
I would have it understood that the mechanism may be slightly modified from
that shown which is in its simplest form without departure from the essential
features of my invention.
Having now particularly described and ascertained the nature of my said in-
vention, and in what manner the same is to be performed, I declare that what I
claim is
1. Crank mechanism suitable for use in driving bicycles and the like comprising

page_text: two sets of chain gearing the driving chain wheels of which are loosely mounted on a
fixed axle and are each provided with a driving arm carrying a pin adapted to slide
in a groove of a pedal lever which is rotatably mounted at one end on a fixed pin or
axle disposed in a direction forward of the axle of the said driving wheel, the
arrangement being such that the path of the pedal is eccentric to the driving wheel
and disposed in a forward direction substantially as described.
2. Crank mechanism constructed arranged and operating substantially as herein-
before described with reference to the accompanying drawings.
Dated this 19th day of Novambo" 1800