Improvements in and relating to Bicycles, Tricycles, and other Velocipedes.
Year: 1890

page_text: Date of Application, 2nd Aug., 1890
Complete Specification Left, 28th Apr., 1891-Accepted, 6th June, 1891
PROVISIONAL SPECIFICATION.
Improvements in and relating to Bicycles, Tricycles, and other
Velocipedes.
I, HENRI FELIX TIRATAY, of Chateau du Loir, Sarthe, in the Republic of
France, Clock and Watchmaker, do hereby declare the nature of this invention to
be as follows:
This invention relates to improvements in bicycles, tricycles and other
velocipedes, and has for its object to provide means whereby the throw of the
crank is increased during that part of its movement in which the power is being
applied.
In carrying out my invention I advantageously mount each pedal eccentrically
upon a disc which is free to rotate in a box or collar secured upon the crank-arm.
Or a box may be secured to the crank axle, the disc working therein being of
sufficient size to obtain the requisite stroke. With this arrangement each pedal is
at the lower part of the disc which carries it and the crank is practically lengthened
or shortened according as it occupies a lower or upper position in relation to the
crank axis.
At the highest part of the path of the pedal the radius of the crank is the
shortest, and as the pedal descends under the pressure of the foot the radius of the
crank gradually increases until it attains its maximum at the lowest point of
the descent. During the second half of the revolution the pedal rises and the disc
which carries it turning at the same time in its box or collar the throw of the crank
is shortened.
The lengthening of the radius of the crank being effected by the rider pressing
on the pedals it follows that the pressure of the foot acting on a longer lever is
applied more effectively than with a crank of normal length, and at the same time
with less fatigue to the rider; the shortening of the crank takes place when no
pressure is exerted on the pedals.
The power exerted on the axis of the wheel of the velocipede while being
greater than with pedals mounted in the ordinary manner does not necessitate an
increased movement of the leg.
Dated the 2nd dor of August 1800
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in and relating to Bicycles, Tricycles, and other
Velocipedes.
I, HENRI FÉLIX TIRATAY, of Chateau du Loir, Sarthe, in the Republic of
France, Clock Maker, do hereby declare the nature of this invention, and in what
manner the saine is to be performed, to be particularly described and ascertained
in and by the following statement :-
This invention relates to improvements in bicycles, tricycles and other
velocipedes, and has for its object to provide means whereby the throw of the
crank is increased during that part of its movement in which the power is being
applied.
In carrying out my invention I advantageously mount each pedal eccentrically

page_text: upon a disc which is free to rotate in a box or collar secured upon the crank-arm-
Or a box may be secured to the crank-axle, the disc, working therein, being of
sufficient size to obtain the requisite stroke.
With this arrangement each pedal is at the lower part of the disc which carries
it and the crank is practically lengthened or shortened according as it occupies a
lower or upper position in relation to the crank-axis.
At the highest part of the path of the pedal the radius of the crank is the
shortest and, as the pedal descends under the pressure of the foot, the radius of the
crank gradually increases until it attains its maximum at the lowest point of
the descent. During the second half of the revolution the pedal rises and the disc
which carries it, turning at the same time in its box or collar, the throw of the
crank is shortened.
The lengthening of the radius of the crank being effected by the rider pressing
on the pedals it follows that the pressure of the foot, acting on a longer lever, is
applied more effectively than with a crank of normal length and, at the same time,
with less fatigue to the rider while the shortening of the crank takes place when
no pressure is exerted on the pedals.
The power exerted on the axis of the wheel of the velocipede while being greater
than with pedals mounted in the ordinary manner does not necessitate an increased
movement of the leg.
To enable my invention to be fully understood I will describe how it can be
carried into effect by reference to the accompanying drawing, in which :-
Figure 1 is an elevation of a safety bicycle shewing my improvements applied
thereto :
Figures 2, 3 and 4 are an elevation, a horizontal section and a transverse section
respectively drawn to a larger scale of the box or collar which carries the pedal
dise and is fixed to the crank secured to the axis of the toothed wheel :
Figure 5 is a section on the line m n of Figure 4:
Figures 6 and 7 are diagrams illustrating the principle of the invention.
A is the box or collar fixed to the crank B; C is the disc mounted upon ball-
bearings in the box or collar A and carrying a spindle D which receives the
pedal E Figures 1, 2 and 4.
In consequence of the disc C being free to rotate in the box or collar A, the
pedal is always located at the lower part of the said disc.
By referring to Figure 6 it will be seen that when the pedal is at the highest
part of its path, the effective radius or throw of the crank is represented by the
distance from the axis O of the chain-wheel F to the centre of the axis a of the
pedal. When the crank has moved through a quarter of a revolution the pedal-
axis occupies the position a¹ and the throw of the crank is represented by the
distance between 0 and a¹; it has therefore increased to an extent equal to the
distance from the pedal-axis to the centre of the disc C. When the crank has
reached its lowermost position, after half a revolution, the pedal always occupying
the lowermost position on the disc C, the throw of the crank is represented by the
distance between 0 and a², equal to O a plus twice the distance of the pedal-axis
from the centre of the disc C. The crank continuing its movement passes through
symmetrical positions and becomes gradually shortened as it rises.
It will therefore be evident that the lengthening of the crank is effected during
the first half revolution, that is to say, during the pressure of the foot on the
pedal.
The lengthening of the crank can be easily modified by varying the diameter
of the pedal-disc C as well as the length of the cranks. The latter can even be
entirely dispensed with by making the pedal-discs large enough and by fixing the
box or collar A on the chain-wheel axis itself, as shewn in Figure 7.
In the latter case the throw, which is always at the maximum when the pedal is
in its lowermost position, is reduced to nothing when it is in its uppermost
position, the axis of the. pedal-then-coinciding with that of the wheel O. "The
maximum of power is thus obtained with the minimum movement of the leg.

page_text: The pedal E is adjusted on its spindle D in the following manner :-
The spindle D is screw-threaded at a, Figure 4, on which screw-thread is a nut e
which bears against a spring r surrounding the socket 6 of the pedal, and pressing
on the flange c thereof gives the pedal a certain rigidity which prevents any
troublesome vibration and oscillation of the pedal on its spindle. A ferrule v
covering the spring protects it from dust.
To prevent the spindle D from becoming unscrewed in the hole made in the boss
of the disc C, I introduce a small screw al.
My system of pedal is applicable to all kinds of velocipedes, bicycles, tricycles etc.
without modifying the general construction of the machines.
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. A driving mechanism for velocipedes in which the pedals are so arranged
with relation to the cranks or their equivalents that the throw of the latter is
automatically and gradually varied during a complete revolution, that is to say, it
is practically lengthened to the maximum during the time the power is being
applied, whilst it is shortened to the minimum during the inactive part of the
stroke, substantially as hereinbefore described with reference to the accompanying
drawing.
2. Mounting the pedals of velocipedes eccentrically on a disc revolving in a box
or collar fixed to the crank of the machine, substantially as herein before described
with reference to the accompanying drawing.
3. Mounting the pedals of velocipedes, provided with the variable throw crank
arrangement referred to in Claim 1, on their spindles in the manner hereinbefore
described, with reference to Figure 4 of the drawing, for the purpose of preventing
vibration and oscillations of the pedals whilst travelling.
4. The improved bicycle hereinbefore described with reference to the accom-
panying drawing.
Dated the 28th day of April 1891
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.