Improvements in or relating to Chain Wheels.
Year: 1896

page_text: This Print is in accordance with the Original Specification as it stands after Amend-
ment (under Section 18 of the Patents &c., Act, 1883) as allowed by the
decision of the Chief Examiner of the 6th day of January, 1898.
Date of Application, 11th Aug., 1896
Complete Specification Left, 22nd Apr., 1897-Accepted, 12th June, 1897
PROVISIONAL SPECIFICATION.
Improvements in or relating to Chain Wheels.
LOUIS COOPER 87 Lower Ford St. Coventry, Cycle Engineer EDWARD
WARD COOPER, 31 Red Lane Coventry, Machinist do hereby declare the nature
of this invention to be as follows:-
Our invention consists in having portions of a wheel radially adjustable, (thereby
increasing the diameter of the wheel as required at points engaged by chain), to
compensate for wear or stretch of latter, thus, as the links or joints of the chain
become longer by wear, they are obviously out of pitch with the teeth of the wheel,
and tend to ride on the top of the latter, causing friction in working and danger of
breakage.
But by having the teeth. or parts, of wheel, radially adjustable, they can be so
raised as to bring the pitch circle to correspond exactly to the chain as it wears or
stretches.
The adjustable parts may be actuated separately, or preferably simultaneously
by a cam disc or a concentric disc with diagonal slots, engaging with movable
parts.
Or the adjustable parts of wheel may be connected by links to a disc or collar
working preferably near the hub of the wheel.
After adjustment, the parts can be firmly locked by a pin and nut passing
transversely through the said parts, and body of wheel.
In practice we find, that a limited number of teeth need only be adjustable, the
remainder being used, only, as a lateral guide for the chain.
The teeth being easily detachable, may be suitably hardened to resist wear and
can be replaced at small cost.
Dated this 8th day of August 1896.
LOUIS COOPER.
EDWARD WARD COOPER.
COMPLETE SPECIFICATION (AMENDED).
Improvements in or relating to Chain Wheels.
We, LOUIS COOPER, 87 Lower Ford St., Coventry, Cycle Engineer EDWARD
WARD COOPER 31 Red Lane, Coventry Machinist, do hereby declare the nature

page_text: 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:-
Our invention relates to chain-wheels for chain gearing such as is commonly
employed in velocipedes and other machinery and has for its objects,-to avoid the
friction arising from the pitch of the chain being longer than the pitch of the
wheel with which it engages, to prevent the chain mounting on the teeth of
the wheel and to reduce the wear on the teeth and make them replaceable. And
our invention consists essentially in making chain wheels with two or more
(preferably three) of the teeth (hereinafter referred to as the driving teeth)
adjustable radially and equally to correspond to the pitch of the chain and, in,
preferably, making the remaining teeth of reduced proportion so that they act as
lateral guides only.
And in order that our invention may be properly understood and readily carried
into effect we will proceed, aided by the accompanying drawings, more particularly
to describe the same.
Figure 1 is a side view, showing a velocipede chain wheel constructed according
to our invention and having one driving tooth, bolt and bar displaced.
Figure II shows a bolt in elevation.
Figure III shows a driving tooth in elevation.
Figure IV is a transverse section on the line 1-1 in Fig. I drawn to an enlarged
scale.
Figure V shows a spanner suitable for adjusting the driving teeth.
Figure VI is a side view of a chain wheel constructed according to our invention
and showing an alternative operating device.
Throughout the drawings similar numerals refer to similar parts.
We construct our improved chain wheel with say three equidistant or approxi-
mately equidistant T shaped radial slots 2, the centre lines of such slots taking the
place of the centre lines of three equidistant or correspondingly approximately
equidistant teeth in a chain wheel of ordinary construction. In each slot 2 a bolt 3
is adapted to slide, which bolt is also adapted to carry a driving tooth 12.
The bolt has a flanged head 4; its shank is of circular form next the head;
adjacent to this part there are two diametrically opposite flats, and the remainder
is screw threaded. The unthreaded parts 5, 6 of the shank are adapted to fit the
hole 13 in the tooth 12 and, say, the hole 9 in the bar 8; the flattened part 6 is
adapted to fit the narrow portion of the slot 2 so that the bolt can slide lengthwise
but not rotate, therein; the threaded part 7 is adapted to receive a lock nut 19.
The driving tooth 12 is provided with lateral projections 14 adapted to fit and
support the part of the chain with which it at any time engages; the projections 14
are adapted also to fit and slide in the wider portion of the slot 2 in the wheel.
The tooth 12 is further provided with a lug 15 projecting towards the centre of
the wheel; the lug 15 is bored transversely with the hole 13 before referred to, it
is also slotted in the plane of the wheel so that it may sit astride the web 16 of
the wheel and bear on the parts of the web adjacent to the slot 2.
All the slots, 2, bolts 3, and driving teeth 12 are facsimiles of each other
respectively. Thus it will be seen that when the said bolts and driving teeth are
mounted in position on the wheel, the said teeth are capable of a radial movement
in the plane of the wheel.
It is important that the driving teeth should all be adjusted equally and to
ensure this we may employ severol devices. According to the method shown in
Figure I to IV we provide the wheel with a concentric boss or projection 24 and
around this we place a closely fitting ring 20. At three equidistant points (21) on
the ring 20 we pivot the inner ends of three similar bars 8. The length of the
bars is suitably greater than the difference between the radii of the pitch circle of
the points 21 and the pitch circle of the bolts 3 when the driving teeth are in their
nearest position to the centre of the wheel. So that if the ring 20 be rotated so
as to bring the bars 8 more nearly into a radial position relatively to the wheel,
all three driving teeth will be moved outward radially and equally from the centre

page_text: of the wheel, thus maintaining them in pitch with each other, whatever that
pitch may be. The teeth may be retracted by rotating the ring 20 in the
reverse direction. The pivot pins at the points 21 may be left somewhat long to
afford a grip for a suitable spanner (Fig. V) by which the ring may be rotated.
The movable parts are locked in position by tightening the nuts 19 on the bolts 3.
According to the method shown in Figure VI we substitute for the ring 20 and
bars 8 a disc 27 the outer edge of which preferably bears against the inner surface
of the shroud 26 of the wheel. The disc 27 is provided with three slots 28,
equidistant and alike in form and position and of a width corresponding to the
diameter of the part 5 of the bolt 3. In this case the inner edges of the slots 28
project the teeth, or the outer edges retract them, according to the direction in
which the disc 27 is rotated. The movable parts are locked in position by
tightening the nuts 19 on the bolts 3, as before.
When the circumference of the chain wheel is so related to the pitch of the
chain that the say three or four driving teeth must be arranged otherwise than
exactly equidistantly the parts of the actuating device also are arranged otherwise
than equidistantly and in such relative positions as correspond with the positions of
the driving teeth.
The driving teeth being detachable may be made of material suitable for
thorough hardening; when worn out they may be readily replaced. By adjusting
the driving teeth to the pitch of the chain, the scraping action which is set up
between the links of a stretched chain and the faces of the teeth of an ordinary
chain wheel, is avoided, as also is the liability of such a chain to mount on the
teeth of the wheel.
By reducing the number of driving teeth to the lowest or almost the lowest
number necessary to prevent slip between the chain and the wheel, the number or
quantity of frictional contacts between the links of the chain and the teeth of the
wheel is correspondingly reduced. We prefer to retain some or all of the other
teeth 29 and to make them of rather less width than the driving teeth, so that
they (29) will not touch the chain in ordinary running, but if the chain sways, they
will prevent its moving so far laterally on the wheel as to foul or mount the
driving teeth as they come round. But we make these other teeth 29 with their
faces set back so that they cannot engage with the links of the chain so as to
drive or be driven by the same.
We wish it to be understood that we do not confine ourselves to the precise
details of construction herein described and illustrated but hold ourselves at liberty
to make such variations and modifications as fairly fall within the scope of our
invention.
Having now particularly described the nature of our said invention and in what
manner the same is to be performed we declare that we are aware that prior to our
invention chain wheels have been constructed in which all the teeth have been
in some cases simultaneously and in other cases independently adjustable for pitch,
the same being set forth, for example, in the Specification of William Biddles
No. 15107 A.D. 1892, and we do not broadly claim the same as our invention; but
what we do claim is:-
1. A chain wheel having some of the teeth adjustable radially to the pitch of
the chain and adapted to act as driving teeth, and others adapted to act as guides
only, substantially as set forth.
2. In a chain wheel, the combination of,-radially adjustable teeth adapted to act
as driving teeth, other teeth adapted to act as guides only, and, means for operating
and locking the adjustment of such driving teeth, substantially as and for the
purpose set forth.
3. In a chain wheel, the combination of, radial slots, bolts adapted to slide in
such slots, driving teeth adapted to move with such bolts, means for operating and
locking the adjustment of such movable teeth and, other teeth adapted to act as
guides only, substantially as and for the purpose set forth.

page_text: 4. In a chain wheel having adjustable driving teeth, the combination with such
driving teeth, of bolts adapted, to slide in radial slots, to carry the driving teeth
in such radial movement, to be operated on by links, slotted discs or equivalent
operating device, and, to receive nuts whereby the movable parts may be locked
in position, substantially as set forth.
5. The improved chain wheel having some of the teeth adjustable radially and
adapted to act as driving teeth, and others adapted to act as guides only,
substantially as herein described with reference to Figs. I, II, III and IV of the
accompanying drawings.
6. The modified construction substantially as herein described with reference to
Figure VI of the accompanying drawings.
7. The improvements in or relating to chain wheels substantially as herein
described and as exemplified in the accompanying drawings.
Dated this 21st day of April 1897
G. DOUGLAS LEECHMAN,
18 Hertford Street, Coventry,
Chancery Lane, London, W.C., and
49 Middle Abbey Street, Dublin,
Patent Agent for the Applicants.