A New or Improved Differential Driving Gear for Cycles.
Year: 1896

page_text: Date of Application, 8th June, 1896-Accepted, 18th July, 1896
COMPLETE SPECIFICATION.
'
A New or Improved Differential Driving Gear for Cycles.
'I, JULIUS KÜSTER of Phaleron near Piræus, Greece, Engineer, 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:-
In cycles generally it has been a great desideratum to provide some means to
vary the ratio of gearing between the crauk shaft and the driving wheel during
motion. This want has been found to be specially inconvenient in hilly neighbour-
hoods or in strong bead winds or other occasions when it is desired to have a lower.
gear so as not to have to exert oneself so much when riding.
Now the present invention relates to means for obviating these drawbacks in
such a manner that in a cycle constructed according to this invention by pressing
upon or moving a lever provided on the handle bar or other part the ratio of
gearing of the chain wheel to the driving wheel is at once reduced say to one half
and amongst other advantages it is possible for example when riding at the highest
speed to reduce if necessary the speed of the wheel, by one half whilst the
velocity of the pedals may remain the same. This is of especial advantage in
crowded thoroughfares.
The improved gear consists essentially of differential bevel wheel gear that is
capable of being thrown into and out of operation by means of a clutch and
that has been found to be very efficient in tricycles to allow of travelling around
curves.
The said gear can be applied either to the crank shaft or to the driving wheel;
the first arrangement has been chosen in the present example.
The throwing into or out of action of the differential gear is effected from the
handle bar. The necessary levers and wires or connections are advantageously
arranged in the hollow parts of the frame. The subject of the invention is
illustrated by the accompanying drawings, in which :-
Fig. 1 is a side elevation of part of a "safety" bicycle provided with the present
invention.
.
Fig. 2 is a horizontal section through the crank axle--on an enlarged
scale-and
Fig. 3 is an elevation of the bevel wheel arranged to revolve on the crank axle.
Fig. 4 illustrates another arrangement for coupling the differential gear with
the crank axle in horizontal section on a still further enlarged scale.
Fig. 5 is a cross section through the crank axle barrel or bearing bracket for
the purpose of illustrating the lever for operating the coupling.
:
On the crank axle a there is arranged to revolve a chain wheel b carrying two
bevel wheels c c one of which is sufficient. These wheels gear on one side with a
bevel wheel d which is fixed on the crank shaft at the left crank f and they gear
on the other side with a bevel wheel e which is mounted loose on the crank axle.
This bevel wheel e can be firmly connected with the crank axle a by means of a
suitable coupling. In the present case a claw coupling or clutch is provided of
the following construction:-
The sleeve 9 of the bevel wheel e is of polygonal form (Fig. 3). On this
polygonal sleeve there is mounted so as to be capable of movement in an
axial direction one part of the "coupling which is formed on both sides with
claws hand k.

page_text: For ordinary or normal gearing the claws are in engagement with the
claws which are fixed to the crank axle a and at same time the bevel wheel e
also revolves with the crank axle and the bevel wheel a fixed upon the latter.
As the crank axle a revolves the small bevel wheels c c do not roll upon
the other two bevel wheels but form with these one piece as it were whereby
the chain wheel & is caused to rotate with the same speed as the crank
axle a.
If now the gearing is to be altered that is to say the velocity of the chain
wheel b is to be reduced by one half whilst the velocity of the pedals remains the
same then the claws are removed from out of the claws by means of the
lever m¹ m. The claws now engage with the claws i whereby the bevel wheel e
is caused to remain stationary.
Now the small wheels e c commence to work and being driven by the bevel
wheel d they roll upon the stationary bevel wheel e and hence the velocity of the
chain wheel b is reduced by one half. For the purpose of operating the coupling
there engages in an annular groove of the same the arm m of the bent lever m¹ m
which is connected with a handler (provided on the handle bar) by means of a
rod g the bent lever p and the wire o. In order to maintain the handler in its
position after it has been operated there is provided a toothed bars and a retaining
pin t.
Another form of construction is shown in Figs. 4 and 5.
In this arrangement one side of the claw coupling is replaced by a friction
coupling. The conical portion of the coupling is pressed by the operation of the
lever mm into the correspondingly conical shaped liner w of the crank axle (or
barrel) which liner may consist of leather rubber or the like.
By this means also the motion of the bevel wheel e can be arrested or
prevented.
In this arrangement the levers m m' and the wire o are arranged as shown in
Fig. 4 in the hollow parts of the framing so as to prevent damage to the same.
As shown in Figs. 3 and 4-there is arranged on the polygonal sleeve of the
bevel wheel e a spring z which has the tendency always to keep the coupling
clutches Ik in gear together. By this means the friction of the lever m in the
annular groove in the coupling is also entirely done away with because the lever m¹ m
strikes or bears at m" (see Fig. 2) against the barrel of the bearing and is held
in this position by the spring n. Even then when by pulling the wire o the lever m² me
moves the claws h into gear with the inclined claws i the said lever does not cause
the slightest friction because in such a ease the claws 4 do not and consequently
also the annular groove u does not rotate.
This differential driving gear with mechanism for throwing the same into
and out of action can be employed also in high bicycles and "front drivers"
it being merely necessary in such cases to modify the shape of the coupling
or clutch.
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 combination with a cycle of a differential gear de ce acting upon the
chain wheel or directly upon the driving wheel said differential gear being
adapted to be thrown into and out of operation substantially in the manner and for
the purposes hereinbefore set forth.
2. In differential speed gear for cycles-the arrangement in the chain wheel b
of two bevel wheels such as cc which have their axes situated diametrically in
said wheel b and which are adapted to gear on one side with a bevel wheel d
fixed on the pedal crank shaft a and to gear on the other side with a bevel
wheel e that is loose on the pedal crank shaft a and that can be rigidly connected
to the pedal crank shaft or axle a by means of a suitable coupling or clutch
substantially in the manner and for the purposes hereinbefore set forth.

page_text: 3. The combination with a cycle of the modified arrangement of a claw coupling
or clutch i k l which is operated from the lever on the handle bar through the
medium of suitable transmitting mechanism substantially as hereinbefore described
with reference to Fig. 4 of the drawings hereunto annexed.
Dated this 8th day of June 1896.
TONGUE & BIRKBECK,
Southampton Buildings, Chancery Lane, London, W.C.,
Agents for the Applicant.