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

page_text: Improvements in and relating to Cranks for Cycles.
I, GEORGE PIRNIE 3 St. Matthew Street Dundee in the County of Forfar
Scotland Rivet Maker 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 in a more efficient manner
than hitherto.
In carrying out my invention, I employ folding or partially folding pieces,
or both, one of these pieces being jointed to about the end of each crank (that is
the outer end). There may be only one piece for each or there may be more.
I may employ sliding pieces, with a guide fixed to the pedal to make them move
outward from or inwards toward the other end of the crank, outward in the
downward motion and inward in the upward.
Springs, spiral or otherwise, keep the folding pieces folded when the cranks are
in upward motion, or when the downward force is taken off the cranks. The pieces
fold by the action of the springs. When folded they keep the foot nearer the
centre shaft on which the cranks are fixed. When power is applied the pieces open
out and then they keep the foot at a greater distance from the aforesaid centre
shaft, or from the other end of the crank.
Projections are, or may be put, on the cranks for putting the springs in a proper
position.
The points of the cranks may be forked, so as to give bearing for the pieces.
According to one modification there is one folding piece for each crank, folding
to a position in which it is about parallel (or nearly so) with the crank.
It opens
out to a position about or near a right angle to the crank, or it may open farther.
Pedals are put on the ends of these pieces. A spiral spring is on one end of the
piece and on the crank, or on a projection of the crank.
Dated this 15th day of September 1894.
Improvements in and relating to Cranks for Cycles.
I, GEORGE PIRNIE, of 3 St. Matthew 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 the power in a more efficient
manner than hitherto.
In carrying out my invention I employ folding or partially folding pieces, one
piece being jointed to about the end of each crank. There may be only one piece
for each or there may be more. Springs (spiral or otherwise) keep the folding
pieces folded when the cranks are in upward motion, or when the downward force
LD

page_text: is taken off the cranks. The pieces fold by the action of the springs. When
folded they keep the foot nearer the centre shaft on which the cranks are fixed.
When power is applied the pieces open out and then they keep the foot at a
greater distance from the aforesaid centre shaft or from the other end of
the crank.
Projections are or may be put on the cranks for putting the springs in a proper
position. The points of the cranks may be forked so as to give bearing for the
pieces. According to one modification there is oue folding piece for each crank
folding to a position in which it is about parallel or nearly so with the crank. It
opens out to a position about or near a right angle to the crank, or it may open
further. Pedals are put on the ends of these pieces. A spiral spring is on
one end of the piece and on the crank or on a projection of the crank.
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 explanatory drawings in which the same reference numerals are used to
indicate corresponding parts in all the figures where shown.
Figure 1. shows a side elevation of my improved crank; Figure 2. is a sectional
part plan at A. A. (Figure 1), and Figure 3. is a sectional view at B. B. (Figure 1.)
looking in the direction of the arrow C.
10. is the crank arm which is fixed to its axle in the usual manner. 11. is a lever
which is jointed to the crank arm by means of a pin 12. 13. and 14. are projections
or stops on the crank arm for the purpose of determining the amount of vibration
of the lever 11. 15. is a spring whose function is to make the lever occupy the
position shown in the drawings, that is to say to cause it to press against the
stop 13, unless otherwise constrained by a superior force. 16. is a guide rod,
jointed at 17. to the lever 11, and guided near its other end by the bracket 18.
19. are adjusting nuts whose chief purpose is to determine the force with which the
spring acts. 20. is a part view of the pedal.
When the crank arm is in its forward position, a downward pressure on the pedal
tends to propel the machine, and the greater such pressure and leverage are,
the greater the propelling force. Conversely, when the crank arm is rising, the
less the leverage and downward pressure the less the retarding force. With
the improved crank such as I have described, the varying leverage becomes
quite possible and consequently the efficiency of the propelling mechanism is
enhanced.
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) 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 crank arms 10, levers 11, pins 12, stops 13. and 14, springs 15, guide rods 16,
pins 17, guide brackets 18, adjusting nuts 19, and pedals 20, substantially as and
for the purposes set forth.
Dated this 10th day of June 1895.
GEO. C. DOUGLAS & Co.,
41 Reform Street, Dundee, Agents for Applicant.