An Improved Chain Wheel for Velocipedes, capable of Expansion and Contraction while the Machine is in Motion, and Apparatus pertaining thereto.
Year: 1894

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Date of Application, 20th Sept., 1894
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Date of Application, 20th Sept., 1894
Complete Specification Left, 20th July, 1895 Accepted, 24th Aug.,
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PROVISIONAL SPECIFICATION.
An Improved Chain Wheel for Velocipedes, capable of Expansion
and Contraction while the Machine is in Motion, and Apparatus
pertaining thereto.
CHARLES MONTague Linley, John Biggs and JOHN ARCHER all of
57 High Street, Clapham in the County of Surrey, Engineers do hereby declare
the nature of this invention to be as follows:-
The object of our invention is to provide a means whereby the gear of cycles
may be readily altered to suit the condition of roads, gradients &c., and consists of
a chain wheel capable of being expanded or contracted by the rider while the
machine is in motion, and apparatus appertaining thereto. The expansion and
contraction may be applied to either or both chain wheels but we prefer to apply
it to the one on the crank or pedal axle. Our chain wheel is cut into two or more
pieces and connected by a joint in the case of two halves and joints in the case of
more than two parts. These joints we will hereinafter more fully describe. For
convenience of description we will take the chain-wheel as being divided into two
equal halves connected by one joint or hinge at the periphery although we do not
bind ourselves to that particular number of sections.
Fixed to our axle we have two eccentrics thrown out in opposite directions, the
amount of eccentricity in each case being half the amount of the expansion required
in the chain wheel. By the side of these eccentrics, but loose on the axle we have
a disc (which we call the fulcrum disc) to which the two halves of the chain wheel
are fulcrated by means of the joint herein before mentioned. Each eccentric is
provided with a strap, and each strap is fulcrated to a section of the chain wheel in
such a manner that when the eccentrics are in a certain position the two halves of
the chain-wheel are drawn tightly together and form a complete wheel; when the
eccentrics are reversed the chain wheel opens on its hinges to a somewhat oval
form leaving a gap on the side opposite to the hinge. From the above it will be
seen that if the fulcrum disc is detained and the axle rotated, a continual opening
and shutting of the chain wheel will take place. From some convenient part of
each half of the chain wheel (preferably the fulcrum of the eccentric strap) we
attach a spring catch or hook capable of locking itself into holes or recesses in the
eccentrics or into a disc fixed to the axle. The object of these spring catches is
that the eccentrics may be turned until the required amount of expansion is obtained
then the hooked portion is allowed to spring into a recess provided at that
particular place in the eccentric or a disc fixed to the axle for that purpose.
will be seen that when these catches are engaging in their recesses no expansion
can take place and it is only when they are both withdrawn from their recesses and
the fulcrum disc detained that the rotation of the axle will produce expansion &
contraction of the chain wheel.
it
Case I. In cases where we wish the expansion to be effected entirely by the
rider's feet, while the machine is in motion we have the spring catches and the
recesses into which they engage bevelled so as to be capable of conveying power in
one direction only. A detaining pawl is fixed to some convenient part of the frame

page_text: in such a position as to arrest the backward motion of the fulcrum disc when it is
in that particular position where the gap in the chain wheel is not embraced by the
chain. In this case it is necessary to have the chain wheel on the axle of
the driving wheel or wheels provided with a ratchet or its equivalent so as to be
able to revolve the chain wheels in a backward direction. The operation of
altering the gear in this case is as follows.
The rider rotates the pedals in a backward direction (the machine still running
in a forward direction by means of the ratchet in the driven chain wheel)-the
detaining pawl stops the fulcrum disc, the chain wheel opens and closes; when the
desired amount of expansion is attained the rider may cease the backward motion
and when forward motion of the cranks is resumed the the spring catches drop into
their respective recesses and cause the two halves of the chain wheel to revolve
with the eccentrics as a whole.
Case II. In this case we regulate the size of the wheel by means of a connection
from some place convenient to the rider's hand. We prefer to use only one spring
catch although we do not bind ourselves to that. We have at some convenient part
of the frame near the chain wheel a sliding block presenting an acute edge to the
chain wheel when the latter revolves in a forward direction. This block is in such
a position that when the chain wheel is revolved it engages the spring catch, which
has a cone attached in such a manner as to engage the oblique edge and withdraw
the spring catch from the hole into which it is engaging. The block has a gap in
it sufficiently large for the conical head of the spring catch to pass through. The
block is capable of sliding up and down in a radial direction to the axle and
actuated and its position determined by the connection above referred to. The
spring catch moves to and from the centre as the half of the wheel to which it is
attached expands and contracts thus it will be seen that if the block is in such a
position that its gap is exactly in the path of the conical head of the spring catch
the latter will pass through the gap at every revolution and no alteration of the
gear will take place but when the block is raised or lowered, the conical head of
the spring catch will come in contact with the acute edge of the block, which will
if rotary motion is continued withdraw the catch from its recess & detain it.
While so detained it will rise or fall as the case may be, until it comes opposite the
gap in the block and will continue to do so until the position of the block is altered.
It must be understood that the gap in the block, must be put in certain positions
which correspond with the recesses in the eccentrics.
Case III. In this case we alter the gear while the machine is stationary & expand
or contract the chain-wheel in the same manner as before and lock it at the desired
diameter by any convenient means such as a screw.
As the wheel expands and contracts the chain will become tight and loose and
we therefore provide pulleys or rollers mounted on spring levers to take up the
slack of the chain. The particular arrangement we prefer is a lever fulcrated near
its centre with a roller at each end and the chain passing over one roller and under
the other. We use a spring with this arrangement so as to keep a constant tension
on the chain. In Case III we have a screw to regulate the tension of the roller.
In some cases we use an oval cam to expand and contract the chain-wheel, we
also in some cases where more than two sections are used in the chain-wheel use a
cam of irregular shape, but in all cases the path of the cam or eccentric is such as
to produce an opening and closing of the section of the wheel by a continuous
revolving of the wheel.
We provide the expanding wheel with flanges to prevent the chain from falling
off should it mount the top of the teeth. The joint or hinge herein before referred
to connecting the sections of the chain wheel we construct in the following manner.
It will be seen that to enable the chain to run properly on the wheel in its different
diameters it is necessary that the axis of the hinge should be exactly on the pitch
line, which with the chain ordinarily in use is impossible. This we do by making
a segmental groove in the side of the wheel, with the pitch line for its centre and a
segment of the same curve working in the groove.

page_text: In some cases we make the joints in the flange at each side of the wheel and
corresponding with the pitch line.
Dated this 20th day of September 1894.
An Improved Chain Wheel for Velocipedes, capable of Expansion
and Contraction while the Machine is in Motion, and Apparatus
pertaining thereto.
CHARLES MONTAGUE LINLEY JOHN BIGGS and JOHN ARCHER all of 57 High
Street Clapham in the County of Surrey, Engineers, 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 :-
The object of our invention is to provide a means whereby the gear of cycles may
be readily altered to suit the condition of roads, gradients &c. and consists of a
chain wheel capable of being expanded or contracted by the rider while the
machine is in motion and apparatus appertaining thereto. The expansion and
contraction may be applied to either or both chain wheels but we prefer to apply
it to the one on the crank or pedal axle. Our chain wheel is cut into two or more
pieces and connected by a joint in the case of two halves, and joints in the more
than two parts. These joints we will hereinafter more fully describe. For
convenience of description we will take the chain wheel as being divided into two
equal halves connected by one joint or hinge at the periphery although we do not
bind ourselves to that particular number of sections. Fixed to our axle we have two
excentrics A thrown out in opposite directions, the amount of excentricity in each
case being half the amount of the expansion required in the chain wheel. Each
excentric is provided with a strap B. and each strap is fulcrated to a section of
chain wheel in such a manner that when the excentrics are in a certain position the
two halves of the chain wheel are drawn tightly together as shown in Fig. 2. and
form a complete wheel. When the excentrics are reversed as in Fig. 1. the chain
wheel opens on its hinges to a somewhat oval form. From the above it will be
seen that if either of the halves of the chain wheel is detained and the axle rotated,
a continual opening and shutting of the chain wheel will take place. From some
convenient part of each excentric strap we attach a spring catch or hook capable
of locking itself into holes or recesses in the excentrics. The object of these spring
catches is that the excentrics may be thrown round until the required amount of
expansion is obtained and then, the hooked portion B. allowed to spring into a
recess provided at that particular place in the excentric. It will be seen that when
these catches are engaging in their recesses no expansion or contraction can take
place, and it is only when they are both withdrawn from their recesses and the
wheel detained that the rotation of the axle will produce expansion and contraction
of the chain wheel.
In cases where we wish this expansion to be effected entirely by the rider's feet
while the machine is in motion as shown in the accompanying drawings we have
the spring catches and the recesses into which they engage as shown by Fig. 3 so as
to be capable of conveying power in one direction only. A detaining pawl or tripping
piece C. Fig. 4 fixed to some convenient part of the frame of the machine in such a
position as to arrest the backward motion of the chain wheel engaging in the stud D.
on the wheel when it is in that particular position where the gap in the chain wheel is
not embraced by the chain as shown by the dotted line in Fig. 1. by the chain.
In this case it is necessary to have the chain wheel on the axle of the driving

page_text: wheel or wheels provided with a rachet or its equivalent so as to enable the chain
wheel to revolve in a backward direction. The operation of altering the gear in
this case is as follows
The rider rotates the pedal in a backward direction (the machine still running in
a forward direction by means of the rachet in the driven chain wheel) the detaining
pawl D stops the chain wheel which opens and closes, and when the desired amount
of expansion is attained the rider may cease the backward motion, and when
forward motion of its cranks is resumed the spring catches B drop into their
respective recesses and cause the two halves of the chain wheel to revolve with the
excentrics as a whole.
In some cases we alter the gear while the machine is stationary and expand or
contract the chain wheel in the same manner as before and lock it at the desired
diameter by any convenient means, such as a screw.
As the wheel expands and contracts the chain will become tight and loose and
therefore we provide pulleys or rollers mounted on spring levers to take up the
slack of the chain.
In some cases we use an oval cam to expand and contract the chain wheel, we
also in some cases where more than two sections are used in the chain wheel use a
cam of irregular shape but in all cases the path of the cam or excentric is such as
to produce an opening and closing of the sections of the wheel by a continuous
revolving of the wheel.
The joints or hinges herein before referred to connecting the sections of the chain
wheel we construct in the following manner. It will be seen that to enable the
chain to run properly on the wheel in its different diameters it is necessary that the
axis of the hinge should be exactly on the pitch line which with the chains ordinarily
in use is impossible.
This we overcome by making a segmental groove in the side of the wheel with a
pitch line for its centre and a segment of the same curve working in the groove.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
First. The use of excentrics to expand and contract chain or sprocket wheels
for cycles for the purpose of producing an alterable gear.
Second. The use of cams with oval or irregular shaped peripheries for the
purpose of expanding and contracting chain or sprocket wheels for cycles, for the
purpose of producing an alterable gear.
Third. The use of spring catches, pawls or clicks in combination with excentrics
for the purpose of expanding and contracting chain or sprocket wheels for cycles
for the purpose of producing an alterable gear.
Fourth. The combination of parts as described in the accompanying drawing for
the purpose herein set forth.
Dated this 20th day of July 1895.
CHARLES MONTAGUE LINLEY.
JOHN BIGGS.
JOHN ARCHER.