Improvements in or relating to the Driving Gear of Velocipedes.
Year: 1894

page_text: Date of Application, 23rd May, 1894
Complete Specification Left, 23rd Feb., 1895-Accepted, 23rd Mar., 1895
PROVISIONAL SPECIFICATION.
Improvements in or relating to the Driving Gear of Velocipedes.
I, JOSEPH ROLAND TOPHAM of 306 Mansfield Road, in the Borough of
Nottingham, Lace Manufacturer, do hereby declare the nature of this invention
to be as follows:―
This invention relates to the gearing of velocipedes and it has for its object
improvements in gearing of the kind in which elliptical or irregular shaped gear
wheels or modifications thereof may be employed for communicating the movement
of the crank axle to the road driving wheel or wheels.
In carrying out this invention an elliptical chain wheel is mounted on the crank
axle, and a second elliptical wheel, preferably of the same size as the former, is
The movement of the
mounted loosely on the axle of the road driving wheel.
wheel on the crank axle may be communicated to that on the driving wheel axle,
by a chain, and from the latter to the driving wheel, by gearing similar in con-
struction to any of those employed in connection with what are known as "geared
ordinaries for increasing the speed of rotation of the driving wheel above that
"
of the crank axle.
In a modification of the above the second elliptical chain wheel may be mounted
loosely on a fixed axle secured to the framing of the velocipede, and the movement
of this wheel be communicated to the road driving wheel and its speed of
revolution increased by an ordinary chain wheel secured to the elliptical chain
wheel and a pinion on the road driving wheel connected by a second chain.
Or in place of the two elliptical chain wheels, toothed elliptical wheels may be
employed and the pivot of the second wheel arranged so as the teeth of the wheels
engage with each other, in which case only one chain would be required.
In a further arrangement the crank axle bearing is mounted preferably on a
swinging frame and the crank axle is provided with a circular toothed wheel the
teeth of which engage with an elliptical toothed wheel pivotted on a fixed axle
secured to the frame of the vehicle; the wheel on the crank axle may be held in
gear with the elliptical wheel by a second idle elliptical toothed wheel pivotted on
a fixed axle on the frame on the opposite side of, and engaging with, the circular
toothed wheel, or by a cam, secured to the elliptical wheel, acting on an anti-
friction roller pivotted to the swinging frame or an extension thereof.
Secured to the elliptical toothed wheel is an ordinary chain wheel, and to the
road driving wheel or axle a pinion, and the movement of the former is communi-
cated to the latter by a chain; the ratio between the driving chain wheel and
pinion being arranged to increase the speed of rotation of the road driving wheel
above that of the elliptical toothed wheel to the required extent.
Doted this 23rd day of May 1894
W. P. THOMPSON & BOULT,
Agents for the Applicant.

page_text: Improvements in or relating to the Driving Gear of Velocipedes.
I, JOSEPH ROLAND TOPHAM, of 11 Newcastle Drive, The Park, late of
306 Mansfield Road, both in the Borough of Nottingham, Lace 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 the gearing of velocipedes and it has for its object
improvements in gearing of the kind in which elliptical or irregular shaped gear
wheels or modifications thereof are employed for communicating the movement of
the crank axle to the road driving wheel or wheels.
It will be best understood by reference to the accompanying drawings in which,
Fig. 1 is a side elevation, and
Fig. 2 a plan showing my invention applied to a rear driven safety bicycle parts
only of the latter being shown.
Fig. 3 is a side elevation and
Fig. 4 a plan showing an alternative arrangement.
Like letters indicate like parts throughout the drawings.
In carrying out this invention the crank axle A may be mounted in a bracket
bearing B of ordinary construction forming part of the framing. The driving
chain wheel C is mounted on the end of a second axle D carried in a bearing E
which is parallel to and may be a duplicate of the bearing B, the movement of
the crank axle A is communicated to the second axle D and chain wheel C by
preferably three eliptical toothed wheels A', D', and F¹.
The wheels A and D' are secured on the axles A and D respectively and the
intermediate idle wheel F¹ may be mounted on a fixed axle secured to an extension
of one or both of the bearings B, E, or it may be secured to an axle F, as
shown, carried in a bearing G which may be of the same construction as the
bearings B, E.
The three bearings B, E, and G may be either formed in a single bracket or
be connected to each other, and in both cases form part of the framing as shown.
The axle F of the intermediate wheel is preferably arranged in the position
shown so that at every half revolution the major axis of the intermediate wheel F¹
is in a line with the minor axis of one of the wheels A', D', and its minor axis in
a line with the major axis of the other, thus forming compound elliptical gear.
In soine cases however the axle F may be connected to the axle D by a circular
wheel and pinion secured on the axles F and D respectively so as to raise the
speed of revolution of the axle D above that of the axle F in order that the
size of the driving chain wheel C may be reduced.
In an alternative arrangement shown in Figs. 3 and 4 a circular toothed inter-
inediate wheel or pinion J is placed between the two elliptical wheels A' D'
This intermediate pinion J is mounted on an axle .J' at the lower end of a swinging
frame or arm K the upper end of which is pivotted to the framing of the
velocipede at K' so that the pinion may oscillate between the two elliptical
wheels AD as will be necessary; for the reason that the radii of these two
wheels which are presented to the pinion J are continually varying in length.
With this arrangement the pinion J is oscillated by these two elliptical
wheels A' D' while remaining constantly in gear with both of them.
If desired the pinion J may be arranged so that it will reciprocate in a rectilinear
instead of (as shown in Fig. 3) a curvilinear path.
The elliptical gear causes the ratio between the road-driving wheel and the crank
axle A to vary every quarter of a revolution of the latter, that is to say, the

page_text: ratio changes from the lowest to the highest and again from the highest to the
lowest every revolution of the crank shaft.
This gives a lower gear every half revolution of the crank shaft than at the
intermediate points, and consequently the cranks have a proportionately quicker
movement and the rider more power at those two points.
The cranks H with respect to the elliptical wheel A' may be adjustable, for
example they may occupy the position shown in full lines in Figs. 1 and 2, in
which case a quick movement of the cranks is obtained over the points above and
below the centre of the crank shaft with a lower gear at those points, or they may
be adjusted to the position shown in dotted lines at H in Fig. 1 and in full lines
in Fig. 3 so that the full advantage of the lower gear may be utilized on the
downward movement of the pedals.
For the purpose of this adjustment the elliptical wheel A' may be secured by
screws or bolts 1 to extensions, lugs, or a flange of the crank H, which latter
may be secured to the crank axle A by a cotter or key in the usual manner.
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 velocipede the combination with a crank axle A of an axle D and.
elliptical gear for connecting the two axles substantially as described and
illustrated in the accompanying drawings.
2. In a velocipede the combination with a crank axle A of a chain wheel-C
axle D and elliptical gear for communicating the movement of the said crank axle
to the chain wheel substantially as described and illustrated in the accompanying
drawings.
3. In a velocipede the combination with a crank axle A of a chain wheel C
axle D elliptical toothed wheels such as A' D' on the axles A and D respectively
and an intermediate elliptical toothed wheel such as F¹ on an axle F substantially
as described and illustrated in Figs. 1 and 2 of the accompanying drawings.
4. In a velocipede the combination with elliptical toothed wheels such as A' D'
of a circular toothed wheel J carried upon a movable support substantially as and
for the purpose described.
5. In a velocipede the combination with a crank axle A. of a chain wheel C
axle D elliptical toothed wheels such as A' D¹ on the axles A and D respectively
and a circular intermediate pinion J on an oscillating frame or arm such as K
substantially as described and illustrated in Figs. 3 and 4 of the accompanying
drawings.
Dated this 22nd day of February 1895.