Improvements in and relating to Cranks for Cycles.
Year: 1896

page_text: Date of Application, 31st Jan., 1896
Complete Specification Left. 27th Oct., 1896-Accepted, 19th Dec., 1896
Improvements in and relating to Cranks for Cycles.
I, DAVID GRAY, of Stanley Buildings, Loons Road, Lochee, in the County of
Forfar, Scotland, Science Teacher, do hereby declare the nature of this invention
to be as follows:-
This invention relates to improvements in and relating to cranks for cycles, the
object being to vary the leverage, that is to say the radius of the crank arm, in a
simple and efficient manner.
In carrying out my invention I fix an eccentric sheave upon the crank arbor and
incorporate the crank with its eccentric strap. Such strap, unless constrained, can
rotate about the sheave. The strap is made to engage with its sheave by means of
a suitable locking gear, such as for example a belt, which is impelled towards
and into one of several notches in the sheave by means of a direct acting spring or
by means of a spring and lever, or their equivalent.
Should the rider desire to vary the radius at which the pedals act, he, without
dismounting, presses the above mentioned lever with his foot, in this manner with-
drawing the bolt from its notch in the sheave. The momentum of the cycle as it
moves forward carries round the eccentric sheave, thus altering the relative
distance of the pedal and the axis of the crank arbor. The locking bolt may be
allowed to drop into any suitable notch, and when once locked the crank remains
in that position; and may be used equally well for propelling the cycle, or for
back pedalling. Although the description given above refers to one crank, it is to
be understood that both cranks of a cycle are treated and actuated in the same
manner.
Dated this 29th day of January 1896.
GEO. C. DOUGLAS & Co.,
41 Reform Street, Dundee, Agents for Applicant.
I, DAVID GRAY, of Stanley Buildings, Loons Road, Lochee, in the County of
Forfar, Scotland, Science Teacher, 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 improvements in and relating to cranks for cycles and
other machines, the object being to vary the leverage, that is to say the radius of
the crank arm, in a simple and efficient manner.
And in order that my said invention and the manner of performing or carrying
the same into effect or practice may be properly understood, I have hereunto
appended two explanatory sheets of drawings in which the same reference numerals
are used to indicate corresponding parts in all the figures where shown.

page_text: Figure 1. is a face view of the crank showing it adjusted to the longest radius.
Figure 2. is a section at A. A. (Figure 1).
Figure 3. is a plan.
Figure 4. is a longitudinal section at B. B. (Figure 1).
Figure 5. is another face view of the crank showing the stop out of gear and
the sheave free to rotate.
Figure 6. is a face view of a modified crank showing it adjusted to the longest
radius.
Figure 7. is a view looking in the direction of the arrow Z. (Figure 6).
Figure 8. is another face view of the modified crank showing the stop out of
gear.
In carrying out my invention, I fix an eccentric sheave 10. upon the crank
arbor 11. and incorporate the crank with its eccentric strap 12. Such strap, unless
constrained, can rotate about the sheave. The strap is made to engage with its
sheave by means of a suitable locking gear, such as for example a bolt 13. which is
impelled towards and into one of several notches 14. in the sheave by means of a
direct acting spring 15. and lever 16. such lever being hinged to the crank by a
bolt and nut 17. and coupled to the bolt by a pin 18.
Should the rider desire to vary the radius at which the pedals act, he, without
dismounting, actuates the above mentioned lever 16. with his foot, in this manner
withdrawing the bolt 13. from its notch in the sheave. The momentum of the cycle
as it moves forward carries round the eccentric sheave, thus altering the relative
distance of the pedal and the axis of the crank arbor. The locking bolt may be
allowed to drop into any suitable notch, and when once locked the crank remains in
that position; and may be used equally well for propelling the cycle, or for back
pedalling. Although the description given above refers to one erauk, it is to be
understood that both cranks of a cycle are treated and actuated in the same
manner.
In the modified crank illustrated by Figures 6. 7. and 8. the lever 16. is actuated
by either the toe or the heel as may be found most convenient. In each of these
modifications the normal position of the lever 16. is illustrated by Figures 1. and 6.
respectively.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
(1.) In cranks for cycles, the combination and arrangement of parts consisting
of the sheave 10, arbor 11, crank 12, bolt 13, notches 14, spring 15, lever 16,
bolt 17, and pin 18, substantially as hereinbefore described with reference to
Figures 1. to 5. of the annexed drawings.
(2.) In cranks for cycles, the combination and arrangement of parts consisting
of the sheave 10, arbor 11, crank 12, bolt 13, notches 14, spring 15, lever 16,
bolt 17, and pin 18, substantially as herein before described with reference to
Figures 6. to 8. of the annexed drawings.
Dated this 12th day of October 1896.
GEO. C. DOUGLAS & Co.,
41 Reform Street, Dundee, Agents for Applicant.