Improvements in the Driving Gear of Bicycles and other Velocipedes.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
Improvements in the Driving Gear of Bicycles and other Velocipedes.
I, WILLIAM FREDERICK WILLIAMS, of 32, Shaftesbury Avenue, London, W.,
Gentleman, do hereby declare the nature of this invention to be as follows:-
My invention relates to the driving gear of bicycles and other velocipedes
and has for its object to combine the advantages of the chainless, and of elliptic,
eccentric or equivalent gear whereby the effective leverage of the pedals is
decreased at the dead points and increased at the points where power may be
most advantageously applied.
The invention consists essentially of driving gear comprising an elliptic
eccentric or equivalent toothed crown or bevel wheel and a pinion adapted to
remain in constant gear therewith, the said gear being applied between the
pedal shaft and the intermediate shaft or between the intermediate shaft and
the wheel or shaft to be driven, or at both points in conjunction
When the elliptic or equivalent gear is employed at both ends of the inter-
mediate shaft the one will supplement the other and admit of the degree of
ellipticity or eccentricity being decreased and where the elliptic gear is in an
increasing ratio between the pedal and intermediate shafts, eccentric gear would
be employed between the intermediate shaft and the hub or shaft driven there-
from.
+
Improvements in the Driving Gear of Bicycles and other Velocipedes.
I, WILLIAM FREDERICK WILLIAMS, of 32, Shaftesbury Avenue, London, W.,
Gentleman, 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:
_
My invention relates to chainless driving gear of bicycles and other veloci-
pedes and has for its object to provide angular gear whereby the effective leverage
T077

page_text: of the pedals is so varied during the revolution of the crank shatt as to enable
the power to be applied to the best advantage.
The invention consists essentially in the combination with the pedal crank
shatt and with the intermediate shaft by which the pedal shaft is geared with
the hub of the driven wheel, of elliptic angular gear: and with the said elliptic
angular gear, of eccentric angular gear between the intermediate shaft and the
hub of the driven wheel, whereby to so supplement the effect of the elliptic
gear as to enable either a greater variation of ratio to be obtained or the ellip-
ticity of the gear to be reduced.
Reference is to be had to the accompanying drawings forming part of this
specification wherein Figure 1 is a face view of an elliptic crown toothed wheel
on the pedal shaft, and Figures 2 and 3 are sectional views on the major and
minor axes of the same wheel and through the pinion on the intermediate shaft
in gear therewith. Figures 4, 5, 6, are similar views of crown pin-toothed gear.
Figure 7 is a face view of an eccentric circular bevel wheel on the intermediate
shaft, and Figures 8 and 9 are sectional views of the same wheel and of the
wheel on the driven wheel hub with which it gears, shewing the variation of
the ratio of the gear. Figures 10, 11, and 12, are similar views of eccentric
crown pin-toothed gear.
The line AA indicates the central vertical longitudinal plane of the bicycle
frame, BB is the centre line of the pedal crank snaft, CC is the centre line of
the intermediate shaft which is usually mounted to rotate in the tubular back
leg of the bicycle frame.
In Figures 1, 2, and 3, D and in Figures 4, 5, 6 D¹, is an elliptic crown
wheel having in the one case radiating teeth and in the other pin teeth, the said
wheel having any suitable degree of ellipticity, that shewn being about 3 for the
major to 2 for the minor axis, the said wheel being fast on the crank shaft.
E and E are respectively the pinions in gear with D or D', the said pinions
being fast on the intermediate shaft. Were the axes BB, CC, of the crank
and intermediate shafts at right angles the pinion would be straight or cylin-
drical, but owing to the oblique relative position of said shafts (which is usual
in chainless cycles) the pinion is conical, its base being towards the axis B,
so that the top of the tooth which for the time being is in gear shall be parallel
with the plane of the wheel D or D as the case may be. The conicity of the
pinion being in the direction described, has for effect to augment the variation
of ratio obtained by the ellipticity of the wheel D or D¹. The elliptic wheel D
or D may be in any required ratio to the pinion E or E¹ in order to gear up
the machine as required.
The position of the pedals with respect to the elliptic wheel D or D¹ should
be approximately in the same radial plane with its major axis.
"
دو
In conjunction with either of the above described forms of elliptic gear
between the crank and intermediate shafts, I use ordinary bevel gear between
the intermediate shaft and the hub of the driven wheel, in order to
gear up
the machine in any required degree beyond the ratio obtained by the elliptic
gear. But provided that the mean diametrical ratio of the elliptic gear described
be as 2 to 1, I may use in conjunction with either form of elliptic gear described,
either of the two forms of eccentric gear shown in Figures 7 to 12, said eccentric
gear being applied between the intermediate shaft and the hub of the driven
wheel and having for effect either to increase the variation of ratio (during such
complete revolution of the pedal shaft) produced by the elliptic gear, or to
permit of the ellipticity of said gear being diminished for a given variation
of ratio during each revolution.
C, C, is the centre line of the intermediate shaft which extends between the
pedal crank shaft and the hub of the driven wheel and which is usually mounted
to rotate in the tubular back leg forming one limb of the fork, FF is the
centre line of the driven wheel.

page_text: G in Figures 7, and 9 is a bevel wheel fast on the rear end of the inter-
mediate shaft, said wheel being circular in form but mounted eccentrically on
the intermediate shaft, so that the ratio of this wheel to the wheel H with which
it gears is varied from a maximum to a minimum and conversely, at each revolu-
tion of said wheel G which makes two revolutions for one of the pedal crank
shaft, these variations being suitably timed to coincide with those positions
of the two pedals at which such variation is desired. The bevel wheel G is
of such form that the teeth all converge to the point of intersection of the
axes CC and F F.
The wheel H is circular, viewed in the direction of its axis, and is mounted
concentrically upon the hub of the driven wheel, and has the same number of
teeth as the wheel G. In consequence of the eccentricity of the wheel G, the
wheel H is oblique to its own axis, but its teeth converge to the point of inter-
section of the axes CC and F F.
Were the axis CC at right angles to the axis FF the wheel G would lie in
one plane, but when the angle made by these two axes is oblique as usual, the
eccentric wheel G is slightly oblique to its own axis as shewn. It will be obvious
that the mean ratio of the wheels G and H being necessarily as 1 to 1, their
relative positions might be interchanged without affecting the result produced
by the variable ratio, that is to say the eccentric wheel G might be fast on the
driving wheel hub and the wheel H fast on the intermediate shaft.
In Figures 10, 11, and 12, G1 is an eccentric crown pin-toothed wheel fast on
the intermediate shaft, and H is a toothed wheel in gear therewith, fast on the
hub of the driven wheel. Were the axes CC, FF at right angles, the wheel H¹
would be straight or cylindrical, but owing to the oblique position of those axes
the wheel H is conical, its base being towards the point of intersection of the
axes CC, FF so that the top of the tooth which is for the time being in gear
will be parallel to the plane of the wheel G. The conicity of the wheel H
being in the direction shewn has for effect to augment the variation of ratio
during a revolution obtained by the eccentricity of the wheel G¹.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, I declare that what
I claim is:
1. In a driving gear of a bicycle or other velocipede the combination with the
pedal crank shaft and with an intermediate shaft by which it is geared to the
driving wheel, of an elliptic crown wheel fixed on the former with its major
axis in about the same radial plane as the cranks and a pinion on the intermediate
shaft in gear with the elliptic wheel substantially as specified.
2. In a driving gear of a bicycle or other velocipede the combination with the
pedal crank shaft and with an intermediate shaft by which the crank shaft is
geared to the driving wheel, the said intermediate shaft making an oblique angle
with the crank shaft as specified, of an elliptic crown pin-toothed wheel fixed
on the former with its major axis in about the same radial plane as the cranks
and a coned pinion on the latter having its larger base towards the axis of the
elliptic wheel so that its varying effective diameter will co-act with the ellipticity
of the crown wheel in varying the ratio of the gear during each half revolution
of the pedal shaft as described.
3. In a driving gear of a bicycle or other velocipede the combination with an
elliptic crown wheel fixed on the pedal crank shaft with its major axis in about
the same radial plane as the cranks and a pinion on the one end of the inter-
mediate shaft, the mean diametrical ratio of the said wheel and pinion being
as 2 to 1, of eccentric angle gear serving to establish driving connection between
the intermediate shaft and the wheel to be driven, said gear being formed of an
eccentric toothed wheel on the one in gear with a circular toothed wheel on
the other, the angular position of the eccentric wheel with regard to that of the

page_text: elliptic wheel being such that they will co-act to vary the ratio between the
pedal shaft and the driven wheel during each revolution of the former substan-
tially as specified.
Dated this 11th day of October 1898.
A. M. & WM. CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.