Improvements in Chain Wheels for Velocipedes, Motor Cars, and like Vehicles.
Year: 1897

page_text: Date of Application, 10th Mar., 1897
Complete Specification Left, 10th Jan., 1898-Accepted, 5th Mar., 1898
Improvements in Chain Wheels for Velocipedes, Motor Cars, and like
Vehicles.
FREDERICK GEORGE ADAMS, of 1, Fentiman Road, Clapham Road, London, S.E.,
in the County of Surrey, Engineer, do hereby declare the nature of this invention
to be as follows:-
My invention consists of a centrifugal adjustment in chain wheels, or sprocket
wheels, used in velocipedes, motor cars, etc. whereby the chain, and chain wheels
may always be kept in perfect pitch and gear with each other. The teeth of chain
wheels are made to slide in grooves or slots formed around the said chain wheels;
or, the teeth may be made to screw into tapped holes around the periphery of wheels
and secured by means of lock-nuts or the like. Therefore when the chain becomes
stretched and out of pitch with chain wheels, the teeth of the said chain wheels may
be adjusted in an outward direction until their pitch becomes the same as that of
the chain.
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Improvements in Chain Wheels for Velocipedes, Motor Cars, and like
Vehicles.
I, FREDERICK GEORGE ADAMS, of 1, Fentiman Road, Clapham Road, London, S.E.,
in the County of Surrey, 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 chain driven velocipedes (such for example as the ordinary rear driven safety
bicycle) and other chain driven vehicles, when the chain becomes stretched, it is com-
mon practice to adjust same by altering the distance between the driving and driven
chain wheels; while this expedient takes up the slack of the chain it obviously does
not alter the pitch of the links which has become increased by wear and tension,
this increased pitch being the general cause of the chain becoming slack. Con-
sequently the pitch of the teeth of the chain wheels does not then accurately coincide
with the altered pitch of the chain links.
Now my invention refers to improved mechanism whereby the pitch or distance
from tooth to tooth all round the wheel can be simultaneously varied and thereby
caused to suit any altered pitch of the chain links, while at the same time and by
Dries B77

page_text: the same motion the periphery of the wheel is also varied, that is, by the action of
increasing the pitch of the teeth the diameter of the wheel is also increased.
I will describe my invention with reference to the accompanying drawing whereon
Fig. 1 is a vertical transverse section of my centrifugally adjustable chain wheel,
Fig. 2 is a side elevation of part of same shewing the wheel before the pitch of teeth
and diameter have been increased, and Fig. 3 is a similar view of part of the wheel
shewing the same when the diameter, and pitch of teeth have been increased.
A is the frame of a chain wheel (which I prefer to form by stamping from sheet
metal) of such formation that radial guides are produced therein at equal distances
apart to each receive a stem or bar B which extends through to the periphery and
is there provided with a head, forming one tooth B' of the wheel, and a segmental
base B of sufficient length to form a bearing surface for the chain links. All the
radial tooth-headed bars B are identical with each other excepting in the length
of the bar or stem part. When the chain with which the chain wheel teeth 13' are
to engage has not become permanently lengthened by excessive strain or wear, then
the base B of each tooth B¹ rests on the periphery of the wheel frame A as shewn
at Figure 2, and the pitch of the teeth B' accurately coincides with the pitch of the
chain.
When however the pitch of the chain links becomes lengthened and the chain
consequently is slack, I then force all the bars B simultaneously radially outwards
as shown at Figure 3, each bar being so advanced an equal distance. To effect this
motion, I provide ehout the axis of the wheel a disc capable of being partially
rotated thereon, and I form in the dise a number of curved grooves or dots (" into
which pins B³ projecting from each bar B enter. The curvature of the slots is
such that when the disc C is partially rotated, all the pins B³, and consequently
the bars B are forced radially outwards simultaneously. In the drawing I have
shewn the pins of two bars B entering one slot C' in the disc C but this is a mere
constructional detail as in some cases each pin B might have a separate slot in the
disc C. Suitable means are provided to retain the disc C in its required position
relatively to the wheel A, such as the lug C projecting from the disc and fixed to
the wheel A by a screw when the disc C has been adjusted to the
required position, but other well known means might be provided to obtain a finer
adjustment.
In order to form radial guides for the tooth-carrying bars B, I generally produce
two circumferential flanges A¹ A³ at proper distances apart upon the wheel A, and
I form apertures in the outer flange A¹ at equal distances apart, corresponding in
number with the number of teeth with which the wheel is to be provided; cor-
responding apertures are also formed in the flange A and the stem or bar of each
tooth passes through an aperture in the flange A³ and a corresponding aperture in
the flange Aª.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is:
1. An adjustable chain wheel for velocipedes and other chain driven vehicles,
wherein the framework of the wheel has a number of equidistant radial guideways,
to receive bars, the end of each bar projecting through the periphery of the wheel,
and having a tooth and extended base to engage and carry the chain; in combination
with a cam grooved plate, concentric with the wheel, and capable of rotary adjust-
ment relatively thereto, the cam grooves acting on projecting parts of the tooth
bars, so that when the plate is partially rotated, the bars, and teeth thereon, are
all simultaneously moved in a radial direction, whereby the pitch of the teeth and
the effective diameter of the wheel are both varied and the chain thereby adjusted
substantially as set forth.
2. In chain wheels for velocipedes and other chain driven vehicles, the com-
bination with the wheel frame or body, and radially extending guide ways thereon.
corresponding with the number of teeth with which the wheel is to be fitted, a

page_text: centrally arranged disc capable of rotation on the wheel axis, eccentrically curved
slots in the disc, and means for fixing the disc to the wheel frame at a required
angular position; of separately formed teeth to engage the links of the chain, a
segmental base part on each tooth to support the links, a stem extending from the
base part of each tooth and calculated to enter and be supported in the radial
guide ways of the wheel frame, and projecting pins on the teeth stems, entering the
slots in the disc aforesaid and by rotation of which latter the teeth are all moved
simultaneously outwards whereby the pitch of the teeth and diameter of the wheel
is increased, substantially as set forth.
3. In chain wheels for velocipedes and other chain driven vehicles, the com-
bination with a wheel frame, an outer peripheral concentric flange thereon, an inner
concentric flange on the frame, a number of apertures formed through the outer
flange, and a corresponding number of apertures formed through the inner flange
in radial lines with the apertures of the outer flange; of separately formed teeth
to engage the chain links, segmental base parts to same to support the links, stems
extending inwardly from the teeth and passing through the slots in the two flanges,
projecting parts on the inner ends of the teeth stems, a centrally arranged disc
capable of rotary adjustment, and eccentric curved slots or grooves in the disc into
which the projecting parts on the teeth stems enter, and by which the teeth are
simultaneously moved radially outwards by rotary movement being communicated
to the disc, and means for fixing the adjustable disc to the wheel frame as set forth.
Dated this 10th day of January 1898.
Dated May or January 1898.
BREWER & SON,
London and Leeds, Agents for the Applicant.