Improvements in and relating to Cranks for Cycles.
Year: 1894

page_text: Date of Application, 15th Oct., 1894
Complete Specification Left, 26th June, 1895-Accepted, 27th July 1895
PROVISIONAL SPECIFICATION.
Improvements in and relating to Cranks for Cycles.
I, GEORGE PIRNIE, of Pirnie and Son, Dundee Rivet Works, East Camper-
down Street, Dundee, in the County of Forfar, Scotland, Rivet Maufacturer, 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, by varying the leverage, to apply power for the rotation of the crank
shaft in a more efficient manner than hitherto.
In carrying out my invention. I mount the pedal spindle on a link which is
jointed to the free extremity of the crank, such joint being preferably fitted with
ball bearings. The link provided with a stop or stops which determine the
amount of its vibration, that is to say its longitudinal axis may be allowed to
move from a position parallel to the crank arm to a position at right-angles to
same, or to a position at an angle greater or less than 90°; or it may vibrate
through an angle of 90° more or less, its central position being at 90° or thereby
to such crank arm. A spring or springs of any suitable type may be used to
bring such link, when no external force is used, to any determined angle with the
crank arm, such as for example, to an angle of 45°; 90°; 135°; or bearing against
it, that is to say the link's longitudinal axis might, by means of such springs, be
brought parallel to the crank arm.
Sometimes I may not employ springs, but use toe clips, or other similar devices
to determine the position of the link relative to the crank arm.
In some cases, in order to simplify the construction, I may employ two links,
one on each side of the crank arm, fixing them together to move as one, suitable
stops and springs being provided for the purposes previously described.
Dated this 12th day of October 1894.
GEO. C. DOUGLAS & Co.,
41 Reform Street, Dundee, Agents for the Applicant.
I, GEORGE PIRNIE, of Pirnie & Son, Dundee Rivet Works, East Camperdown
Street, Dundee, in the County of Forfar, Scotland, Rivet 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 relates to improvements in and relating to cranks for cycles, the
object being, by varying the leverage, to apply power for the rotation of the
crauk shaft in a more efficient manner than hitherto.
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.
J

page_text: Figure 1. (Sheet 1.) shows a side elevation of my improved crank, Figure 2.
being a view looking in the direction of the arrow B. (Figure 1.), while Figure 3.
is a cross-section at A. A. (Figure 1.1.
Figure 4. (Sheet 2.) is a side elevation of a bicycle showing the pedal at its
least radius, Figure 5. in a similar manner showing such pedal when at its
maximum radius.
In carrying out my invention, 1 mount the pedal spindle 10. on a link 11. which
is jointed to the free extremity of the crank 12. Such joint may be fitted with
ball bearings. The link 11. or the crank 12. is provided with a stop or stops 13.
which determine the amount of its vibration, that is to say its longitudinal axis
may be allowed to move from a position parallel to the crank arm to a position
at right angles to same, or to a position at an angle greater or less than 90°; or
it may vibrate through an angle of 90° more or less, its central position being
at 90° or thereby to such crank arm. In the drawings the link is designed to
vibrate from c. to y. as shewn in Figure 1. A spring 14. guided and supported
by a rod 15. or otherwise springs of any suitable type may be used to bring such
link 11, when no opposing external force is used, to any determined angle with
the crank arm, such as for example, to an angle of 45°; 90°; 135°; or bearing
against it, that is to say the longitudinal axis of the link might, by means of such
spring or springs, be brought approximately parallel to the crank arm, or to the
position x. shown by the full lines in Figure 1.
The guide 15. is hinged at 16. to the link 11, its other extremity being held and
supported by the bracket 17; adjustable nuts 18. and 19. being provided for the
purpose of regulating the tension of such spring 14.
In some cases, in order to simplify the construction, I may employ two links,
one on each side of the crank arm, fixing them together to move as one, suitable
stops and springs being provided for the purposes previously described.
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
(i.) The herein before described combination of parts for varying the effective
leverage of the crank pedal.
(2.) The combination and arrangement of parts consisting of a cycle with the
pedals, 10, the links 11, crank arms 12, stops 13, springs 14, guides 15, joints 16,
brackets 17, adjusting nuts 18. and 19, substantially as and for the purposes set
forth.
Dated this 25th day of June 1895
GEO. C. DOUGLAS & Co.,
41 Reform Street, Dundee, Agents for Applicant.