Improvements in Pedal Motors, chiefly designed for use on Bicycles.
Year: 1891

page_text: The decision of the Comptroller-General, of the 23rd day of December 1893,
allowed, under Section 18 of the Patents, &c. Act, 1883, an Amendment of
this Specification.
Date of Application, 4th Aug., 1891-Accepted, 19th Sept., 1891
COMPLETE SPECIFICATION (AMENDED).
[Communicated from abroad by JOHN THOLEN, Hotel Keeper, and CHARLES
PHILLIPS, Inventor, both of 64, North Canal Street, Chicago, Illinois, United
States of America.]
Improvements in Pedal Motors, chiefly designed for use
on Bicycles.
I, HENRY HARRIS LAKE, of the firm of Haseltine, Lake & Co., Patent Agents,
45 Southampton Buildings, in the County of Middlesex, 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 more particularly to pedal motors for bicycles and other
purposes, and consists in combining certain beams and bars with a pair of cranks
whereby I overcome the dead points and secure an increase of power.
In the accompanying drawing I have shown my invention applied to a safety
bicycle.
Figure 1 is an elevation from the left right side, of a bicycle showing the right
left hand crank just completing a down stroke.
Figure 2 is a similar view but with the right left hand crank just started on its
down stroke.
"
Figures 3, 4 and 5 are diagrams showing different positions of the cranks and
connections.
1 is the usual frame of the bicycle. 2 are hangers on the rear wheel fork. 3 is
the crank shaft mounted in the usual manner and connected with the wheel by
sprocket pinions and chains, as shown. 4 and 5 are the cranks, set, as usual,
diametrically opposed to the shaft. 6 and 7 are radius bars or beams pivoted at
their ends to the hangers 2, and connected at their front ends by links 8 and 9 to
the cranks 4 and 5, respectively. 10 and 11 are depending arms integral with or
rigidly connected to the front ends of beams 6 and 7. 12 and 13 are the treadles
adjustably secured in the usual manner to the arms 10 and 11. For convenience [
have used the even numbers 4, 6, 8, 10 and 12 to designate the members on the
right hand side of the machine, and the corresponding odd numbers for those on the
left. In practice I have found it best to use the following proportions, viz. :-
I fix the pivotal point, 2, at a distance above the level of the crank shaft equal to
three-fourths of the length of the crank arm. I then make the beams equal in
length to the distance from the centre of the crank shaft to the centre of the pivotal
point 2, and the links 8 and 9 equal to the same distance, less the length of the
crank arm.
The arms 10 and 11 may be of a length to suit the legs of the rider of
the machine.

page_text: The manner in which I overcome the dead points and gain power is illustrated
in Figures 3 and 4. Figure 3 shows that when one of the cranks, as 4, is on its
upper dead point, the other crank has not yet reached its lower dead point, and
Figure 4, shows that when one of the cranks, as 4, is on its lower dead point, the
other one has passed its upper dead point. In other words, the two cranks are 5
never both on their dead points at the same time, and there is thus always a margin
of power available to drive them over their respective dead points. The motion of
the treadles 12 and 13 being in a small arc of the circle whose centre is at the
pivot 2, is substantially a vertical motion, even at its upper and lower limits; hence
the weight of the rider and the direct push of his leg is available through the 1
entire stroke to a greater degree than where the treadle moves more or less
horizontally, as it does when attached directly to a crank arm.
It is obvious that the beams, links and cranks proportioned and arranged as above set
forth, will cause the point of connection between rach link and its corresponding beam to
describe an are the greater part of which is behind (that is on the side of the pivotal 1
point 2) a straight line drawn through the centre of crank-shaft 3 and at right angles to
a line drawn through the pivotal point 2 and the connecting point between the link and
said beam, when the beam is at the limit of its downward motion. If this relation of
said are to said line is changed there will be either a loss of power or too rapid a motion
of the beam on its return stroke.
It will be observed that on the down stroke of the pedal during the first quarter of the
cranks revolution, that is in passing from the rertical to the horizontal position the
connecting point between the link and beam moves through a much longer are than during
the second quarter of the crank's revolution hence the motion of the joot during the first
quarter is faster than during the second quarter, and the power exerted is proportionately
greater; at the same time, the relocity and motion of the pedal gradually diminishes
during the second quarter until at the extreme of the doun stroke there is an appreciable
period of practical rest thus enabling the muscles to recover preparatory to the
up-stroke.
When the pedal is in its elevated position, at the beginning of the down stroke, there is
no such pause, the change in the direction of motion being instantly effected.
The effective power exerted upon the crank is applied and distributed to the greatest
advantage by the arrangement of parts described, in that at the beginning of the down
stroke the pedal occupies a position in advance of the crank pin, and power is transmitted
to the latter through the link from a point in rear of the pedal. As the crank pin
adrances the angle between the link and beam is increased, and a toggle action is developed
which latter increases in power until the crank pin reaches its most forward position and
stands in substantially a horizontal plane; from this point the link gradually approaches
the pedal, and a perpendicular thrust is developed upon the crank pin, the power
diminishing as the crank arm and link come into line but before this occurs the opposite
pedal has reached a point where it exerts effective power.
Not only is the effective power
increased by this means but the path traversed by the foot is shortened being appreciably
less than if the pedal were applied directly to the crank.
I have shown my invention as applied to a bicycle, but it is equally applicable
to other machines driven by cranks.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, as communicated to me
by my foreign correspondents, I declare that what I claim is :-
First. The combination, substantially as set forth, with the frame and wheels of
a safety bicycle, of a crank shaft journalled to said frame and connected to the
driving wheel by suitable transmitting mechanism, two cranks oppositely attached
to said shaft, beams, as 6 and 7, fulcrumed above the level of the shaft to the frame
behind the shaft and extending forward over the shaft, links connecting the cranks
with the free ends of the beams, and pedals connected to the free ends of the beams
for operating the same.

page_text: Second. The combination, substantially as set forth, of the cranks oppositely
connected to a shaft, the beams fulcrumed above the level of the said shaft and
extending over the cranks, the links connecting the beams and cranks, the arms, as 10
and 11, rigid with the beams and the treadles on said arms.
Dated this 4th day of August 1891.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.