Improvements in Cycle Cranks.
Year: 1896

page_text: 1, WILLIAM JAMES STEVENSON STRANGE, of Dormer Lodge, Leamington,
in the County of Warwick, Gentleman, do hereby declare the nature of this
invention to be as follows:-
This invention relates to cycle cranks having a variable throw, wherein the
throw is lengthened by the downward thrust of the foot and shortened again as
the crank rises.
My invention consists in the combination and arrangement of parts hereinafter
described.
According to one method of carrying out my invention, I place a sleeve over the
end of the crank said sleeve being held in place so as to be free to slide
longitudinally without turning on the crank by any suitable device, such as a slot
and pin. A spring is disposed within the said sleeve and exerts its force to draw
the latter towards the crank axle. The said sleeve carries the pedal pin and the
downward thrust of the foot extends the spring and lengthens the throw which is
shortened again by the action of the spring as the crank rises.
According to another method of carrying out my invention, the pedal pin is
secured to a slide on the crank, from which slide extend suitable guide rods passing
through holes in a cross head or projections on the crank end. A spring is
interposed between said crosshead and the slide which spring is compressed by the
pressure of the foot on the downstroke and by its expansion on the rise of the crank
returns the slide to its normal position.
Dated this 2nd day of L. 1900
E. P. ALEXANDER & SON,
Chartered Patent Agents,
19, Southampton Buildings, Chancery Lane, London, W.C., Agents.
Improvements in Cycle Cranks.
I, WILLIAM JAMES STEVENSON STRANGE, of Dormer Lodge, Leamington,
in the County of Warwick, Gentleman, 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 cycle cranks having a variable throw, wherein the
throw is lengthened by the downward thrust of the foot and shortened again as
the crank rises.
My invention consists principally in the combination and arrangement of
parts hereinafter described with reference to the accompanying drawings,
wherein :-
Fig. 1 is a sectional elevation of a cycle crank constructed according to my
invention

page_text: Fig. 2 is a section on line - Fig. 1 and,
Figs. 3 and 4 are sectional elevations of slightly modified constructions.
Similar letters refer to:like parts in all figures.
A crank constructed according to my invention is of telescopic construction and
comprises two main parts or members, viz., a sleeve A and a plunger B sliding
therein. Rotation of the plunger within the sleeve is prevented by the bolt c
which passes through the sleeve A and through a slot d in the plunger B,
(Figs. 1, 2 & 3). One member of the crank is secured to the crank axle and the
other carries the pedal pin. In the drawings the sleeve A is represented as
adapted for being fixed to the crank axle, and the plunger B as adapted for the
reception of the pedal pin, but this arrangement may obviously be reversed.
C (Fig. 1) is a spring surrounding the plunger B and confined between a collar e
thereon and a collar el fixed in position within the sleeve a by the bolt c. The
spring C is thus compressed when the crank is extended by the down thrust of the
foot on the pedal, and as the crank rises draws the plunger back into the sleeve by
its expansion and so shortens the throw again.
In the modification Fig. 3, I have represented springs C1 C1 outside the crank
as substituted for the spring C within the sleeve. These springs are secured at
either end to the eyes on the ends of the plunger and sleeve respectively, and
are extended by the lengthening of the crank on the down stroke, shortening the
throw again by their contraction on the rise of the crank as in the first described
arrangement.
In the modification Fig. 4, in lieu of a slot d in the plunger A, I form slots d in
the sleeve B, the pin c passing through a hole in the plunger and moving with the
latter.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is
1. A telescopic cycle crank comprising the members A and B sliding one within
the other and respectively adapted for connection at their ends with the crank
axle and pedal pin, combined with a spring or springs whereby the crank throw
is automatically shortened again after being extended by the thrust of the 'foot,
and means for preventing the rotation of one member within the other, substan
tially as described.
2. The combination and arrangement of parts constituting a cycle crank,
substantially as described with reference to and illustrated in Figs. 1 and 2 of the
drawings.
3. The combination and arrangement of parts constituting a cycle crank,
substantially as described with reference to and illustrated in Figs. 3 and 4 of the
drawings
Dated this 29th day of March 1897.
E. P. ALEXANDER & SON,
Chartered Patent Agents,
19, Southampton Buildings, Chancery Lane, London, W.C., Agents.