AN IMPROVED TWO-SPEED GEAR FOR VELOCIPEDES
Year: 1884

page_text: I WILLIAM MORRISON SIMPSON of No 58 Elphinstone Road Hastings in the
County of Sussex, Gentleman, do hereby declare the nature of my said invention
for AN IMPROVED TWO-SPEED GEAR FOR VELOCIPEDES to be as follows:-
My gear belongs to that class known as "power" gears, that is to say, the speed
obtained through the working of the gear is inferior to the normal gear of the
Machine.
I prefer to place my gear on the crank axle, in which case it is constructed as
follows: I mount loosely, on the axle a combined chain wheel, & internal spur
wheel. Mounted loosely on the axle is also a small eccentric disc, this disc forms a
bearing for a loose spur pinion which gears with the internal spur wheel. Keyed
or otherwise fixed on to the axle, in a suitable position is an arm, which I call a
crank arm, as it is the driver of the whole mechanism. The extremity of this
crank arm is provided with a slot, into which a pin fixed to the loose spur pinion
takes, & by which motion is transmitted from the axle, through the crank arm, to
the pinion; the slot allowing the pin to travel radially as the pinion travels round
the eccentric disc. Fixed to the eccentric disc, but outside the cover enclosing the
gear, is a short arm for the purpose of controlling the gear. If this arm is prevented
from revolving, the eccentric disc to which it is fastened, is hold stationary, &
consequently the spur pinion travels round it & drives the internal spur wheel,
and the chain wheel which is part of it, at a slower speed than the crank axlo; but
if the arm is released & allowed to revolve freely the whole mechanism revolves as
one piece, and the chain wheel is driven at a speed identical with the speed of the
crank axle.
It will be seen that the construction of this gear is not complex, & that the
working parts are few, while the arrangement for controlling the variations of speed
is exceedingly simple, as all that is required is an adjustable stop on the frame of
the machine, which may be either set to prevent the arm attached to the eccentrio
dise from revolving or to allow of its free revolutions.
ROBT. ED. PHILLIPS,
Agent for the Applicant.

page_text: I WILLIAM MORRISON SIMPSON of No. 58 Elphinstone Road Hastings in the
County of Sussex, Gentleman do hereby declare the nature of my invention for
AN IMPROVED TWO-SPEED GEAR FOR VELOCIPEDES and in what manner the same
is to be performed, to be particularly described and ascertained in and by the
following statement :-
My gear belongs to that class known as "power" gears, that is to say, the speed
obtained through the working of the gear is inferior to the normal gear of the
machine.
I prefer to place my gear on the crank axle, in which case it is constructed as
follows: I mount loosely on the axle a combined chain wheel & internal spur
wheel. Mounted loosely on the axle is also a small eccentric disc; this disc forms
a bearing for a loose spur pinion which gears with the internal spur wheel. Keyed
or otherwise fixed on to the axle, in a suitable position is an arm, which I call a
crauk arm, as it is the driver of the whole mechanism. The extremity of this
crank arm is provided with a slot, into which a pin fixed to the loose spur pinion
takes, and by which notion is transmitted from the axle through the crank arm to
the pinion, the slot allowing the pin to travel radially as the pinion travels round
the eccentric disc. Fixed to the eccentric disc but outside the cover enclosing the
gear is a short arm for the purpose of controlling the gear. If this arm is prevented
from revolving the eccentric disc to which it is fastened is held stationery and
consequently the spur pinion travels round it and drives the internal spur wheel,
and the chain wheel which is part of it, at a slower speed than the crank axle, but
if the arm is released & allowed to revolve freely the whole mechanism revolves as
one piece and the chain wheel is driven at a speed identical with the speed of the
crank axle.
It will be seen that the construction of this gear is not complex and that the
working parts are few, while the arrangement for controlling the variations of speed
is exceedingly simple, as all that is required is an adjustable stop on the frame of
the machine, which may be either set to prevent the arm attached to the eccentric
disc from revolving or to allow of its free revolutions.
In order that the construction of my gear may be fully understood I will more
particularly describe it with the aid of the accompanying drawing; on which
similar parts are marked with corresponding letters of reference. Fig. 1 is a cross
section and Fig. 2 an elevation (with the cover plate removed) of my gear. A is
the combined chain wheel and internal spur wheel mounted loosely on the axle B.
C is the eccentric disc and D the spur pinion mounted on it and gearing with the
internal ring of teeth on the chain wheel A. E is the crank arm keyed or otherwise
fixed to the axle having a slot e embracing the pin d fixed to the spur wheel D.
a is the cover
F is the controlling arm keyed to the boss of the eccentric disc C.
fixed to the chain wheel A. to enclose the gear and exclude the dust and dirt.
Figs. 3 & 4 are a cross section and an elevation (with the cover plate not
removed) of a modification of the gear in which the spur pinion D is provided with
an internal ring of teeth and is driven by the disc E having a set of pin teeth d
by this arrangement the excessive wear and strain that is thrown on the crank
arm E and the pin d of the arrangement as shown by Figs 1 & 2 is distributed
amongst the set of pin teeth ḍ and the internal ring of teeth on the pinion D of
the modified arrangement.
Figs 3 & 4 also show an arrangement for locking the eccentric disc C with the
chain wheel A if it is found necessary to do so. The arrangement consists of fixing
a ring of teeth on the boss of the cover a attached to the chain wheel, the cover

page_text: being made strong enough and fixed rigidly enough to the chain wheel to be to all
intents and purposes part of it, and pivotting on the controlling arm a short lever
having a tooth at one end, which engages with the ring of teeth fixed on the
cover a, which locks the controlling arm and with it the eccentric disc, to the chain
wheel. A spring acting between the locking lever and the controlling arm, keeps
the tooth on the lever in contact with the ring of teeth on the cover of the
chain wheel.
It will be seen that when the adjustable stop is set to stop the revolution of the
controlling arm, the locking lever will first come in contact with the stop and press
the free end of it back into contact with the end of the controlling lever thereby
unlocking the eccentric disc from the chain wheel & stopping the revolution of the
controlling arm at the same time.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I do declare that what
I claim is
First: The construction of a two speed gear substantially as herein before
described and shown by Figs 1 & 2.
Secondly: The loose eccentric disc O in combination with the pinion D as and
for purpose herein before described and shown by Figs 1, 2, 3 & 4
Thirdly: The driving arm E in combination with the pinion D as and for the
purpose described.