Improved Speed-varying Mechanism for Cycles Driven by Chain-gear.
Year: 1895

page_text: Date of Application, 1st Apr., 1895
Complete Specification Left, 30th Dec., 1895-Accepted, 8th Feb., 1896
PROVISIONAL SPECIFICATION.
Improved Speed-varying Mechanism for Cycles Driven by
Chain-gear.
I, HUGO EXNER of 29 Hauptstrasse, Helzendorf near Vienna in the Empire
of Austria, Railway Servant, do hereby declare the nature of my said invention to
be as follows:-
This invention relates to a mechanism for regulating and varying the speed of
cycles driven by chain gear, its object being to enable the rider to readily vary the
ratio of speed and power.
In order to maintain an almost uniform rate of speed, it must be possible to vary
the power transmitted, seeing that on travelling over undulating ground, the power
required to propel the cycle must necessarily be greater than that sufficing for
running on level ground or on making descents.
According to this invention, the necessary variation in speed is effected by
toothed step-wheels or several toothed wheels, connected with each other, such
wheels of different diameter being mounted on the pedal axle (or on an axle for
the toothed wheels) and on the hub of the wheel to which the power is to be
transmitted respectively.
For varying the speed, the said hub (or the toothed wheels mounted thereon)
and the pedal axle (or the toothed wheels mounted on same) are made to approach
each other, or one of these parts (hub or pedal-axle) may be stationary. When
the pedal-axle and the hub of the back-wheel thus approach each other, the
chain is slackened and may be put onto another pair of wheels of different
diameter, a corresponding variation in speed being thereby effected.
This variation in the relative positions of both axles of the toothed wheels or of
the wheels themselves, to each other, is effected either by means of one or more
cams, or by moving the axle of the toothed step-wheels in an adjustable slide or,
finally, by imparting a tilting or turning movement to one of the axles of the
toothed wheels.
The mechanism for effecting the said variation by means of a cam consists
essentially of a series of toothed wheels of different diameters mounted on the
pedal axle and the wheel-axle respectively, round which wheels a chain runs in the
usual manner. The chain wheels mounted on the pedal-axle carry a cam coupled
to same by means of a wedge, screw key, or the like; on releasing such wedge the
cam and the chain-wheels may be operated quite independently of each other. If
now the pedal-axle together with the cam is turned 180° by means of the pedal
arm, the wheels on the pedal axle advance in horizontal direction to twice the
extent of eccentricity of the cam, towards the wheel which is to be driven. Such
movement slackens the chain and allows of same being put onto another pair of
wheels of different diameter, a corresponding variation of speed being thus effected.
The pedal-axle, together with the cam is now turned back to its normal position
and the said key, screw, or the like inserted again, when the cycle is ready for
riding.
The cam may also be adjustably or releasably attached to the sleeve of the
pedal-axle and the wheels keyed onto the latter; or two cams may be employed,
which are connected by bolts and securel to the sleeve of the pedal axle by
screws or in any other suitable manner. The variation in this instance is also

page_text: effected by turning the cams to the extent of 180° and thus reducing the distance
between the wheels mounted on the pedal axle and the transmitting wheel. It
will also be evident that the rims of the chain-wheels of different diameter
may be detachably secured by bolts or the like to one and the same hub of the
pedal-axle.
When two cams are employed by the aid of pawls and springs one may be
utilized for effecting the variation of speed and the other for keeping the chain
at the proper tension.
The same effect may be arrived at by mounting the axle of the wheel of the
cycle in slides adjustable by means of screws in the bifurcated ends of one of the
parts of the frame. Such screws may be in connection with bevel wheels and on,
being operated, effect the simultaneous and like movement of the said slides.
The adjusting screws may also be in direct connection with the slide on which the
axle of the back-wheel is mounted.
According to another arrangement, either the axle of the wheel to be driven, or
the pedal axle, or both, is or are so mounted in brackets, preferably forked, or in
crank arms, that, after releasing clamping screws or the like for keeping the parts
stationary, such brackets or arms may be operated and the axles thus moved to and
from each other; the chain can thus be put onto another pair of wheels in the
manner afore described.
Dated this 1st day of April 1895
A. F. SPOONER,
124 Chancery Lane, W.C., Agent for the Applicant.
Improved Speed-varying Mechanism for Cycles Driven by
Chain-gear.
I, HUGO EXNER, of 29 Hauptstrasse, Holzendorf near Vienna in the Empire
of Austria, Railway Servant, do hereby declare the nature of my said 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 a mechanism for regulating or varying the speed of
cycles, its construction being such that the rider can readily vary the speed as
desired.
Most of the mechanisms at present in use are defective in so far that they can
only be attached to cycles specially constructed for receiving same; or, if it be
desired to attach same to cycles of other constructions, much time and labour
must necessarily be expended thereon.
The great advantage of my improved mechanism is, that it may be easily
attached to any cycle without any alterations being necessary and hence without
entailing much expense.
I will now describe my invention with reference to the accompanying drawing in
which.
Fig. 1 is a side view of the mechanism, the two front wheels of the cycle not
being shown.
Fig. 2 is a horizontal section through same.
Fig. 3 shows the device for coupling the cam and step wheel
Figs. 4 and 5 are modifications of same.
a' is a cam (with excentricity ) keyed directly onto the pedal-axle a and carrying
the toothed step-wheel b. The latter is coupled to the cam a' in such manner that
it may be readily released for varying the speed i.e. for putting the chain onto
another pair of wheels.
The wheel b may be of one piece, or, as shown in the drawing of several

page_text: parts, which even when not secured by the cam are prevented from lateral
displacement by a rib or flange such as a 2.
The wheel is mounted so that its axis coincides with that of the pedal axle a.
For varying the speed, the wheel b and cam a' are uncoupled by turning the
pedal to the extent of 180° in the direction shown by the arrow in Fig. 1.
In so
doing, the wheel b is prevented by the chain from participating in such movement
and thus the wheels, but not their axes, approach each other to the extent of 2.c.
As soon as the chain is changed, the cam is turned back and coupled with
the wheel b again either by hand or automatically.
C
The coupling shown in Fig. 1, 2 and 3 consists of the wedge or key e placed in
the cam and whose screw c¹ is screwed into the small wheel d, which latter may be
rotated from without.
In the modifications shown in Fig. 4 and 5, the wedge c is automatically returned
to the locked position by spring e.
As illustrated in Fig. 4, the wedge c is released by turning the clutch with a key;
and in Fig. 5, by simply pressing same, preferably at both sides, with the hand
into its bearing.
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. An improved speed varying mechanism for cycles driven by chain-gear,
comprising a cam (a¹) mounted on the pedal-axle and carrying several chain-
wheels (3, 3) to which latter it is coupled by releasable coupling (c),
substantially as described and shown in the drawing.
2. In a speed-varying mechanism for cycles as set forth in Claim 1, a wedge (c)
radially adjustable by turning a small wheel (d) in which is screwed a bolt (c) of
wedge (c), substantially as described and shown in the drawing. (Figs. 2 & 3.)
3. In combination with a speed-varying mechanism for cycles as set forth in the
foregoing claims, spring (e) put under tension by wedge (c) and automatically
returning the latter to its locked position, substantially as described and shown in
Figs. 4 and 5 of the drawing.
Dated this 30th day of December 1895.
A. F. SPOONER,
124 Chancery Lane, W.C., Agent for the Applicant.