Improvements in Chain Wheels for Velocipedes and other Vehicles.
Year: 1897

page_text: Date of Application, 9th Jan., 1897-Accepted, 6th Mar., 1897
COMPLETE SPECIFICATION.
Improvements in Chain Wheels for Velocipedes and other
Vehicles.
I JAMES MAGNUS SMITH of Lerwick, Shetland, North Britain, Painter 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 :-
This invention relates to improvements in chain wheels for use with velocipedes
and other vehicles and has for its object to provide means for automatically
applying a brake during the act of back pedalling.
For this purpose I construct the said chain wheel in two separate parts viz., an
outer part fitted to and capable of sliding upon an inner or central part, each
of the said parts being provided with grooved projections and tongues engaging
with and sliding upon one another. Gaps or spaces are formed in the tongues
corresponding with the projections to permit of the two parts being detached from
one another. The central part is mounted upon the crank axle, when the invention
is applied to a velocipede and each of the said parts is provided with a lug to
which are attached the end of a spring band which surrounds a drum fixed to the
frame of the machine.
During the forward pedalling the two parts of the wheel are locked together and
act as a solid wheel but as soon as back pedalling commences the outer part slides
round the central part thus drawing the two ends of the spring band nearer together
and tightening the latter around the fixed drum.
This action gradually causes the outer part to cease revolving and consequently
serves as a brake to the vehicle thus obviating the use of the ordinary brake rods
and levers the mere act of back pedalling causing the brake to be applied.
The sliding parts of my improved wheel should be made of a standard size so
that a larger or smaller outer or toothed part may be used as desired for changing
the gear one or more links of the chain being also added to or taken off the chain
for this purpose.
Should the band brake not be used in conjunction with my improved wheel one
or more of the grooved projections may be provided with a screw or screws for
fixing the parts together and preventing their sliding motion. And in order to
clearly understand my said invention and the manner of its application I will
describe the same with reference to the accompanying sheet of drawings in which
Figure 1 is an inner or reverse side view of my improved wheel and
Figure 2 is a cross section on the linex of Figure 1.
Figure 3 is a side view of the inner or central part of the wheel and Figure 4 is
a section on line y y of the same.
Figure 5 is a side view of the brake drum.
a is the outer or toothed part of the wheel and b the inner or central part fixed
to the crank axle c. The part a is formed with the grooved projections a¹ and
tongues a 2 which engage with similar grooved projections & and tongues 62 on
the part 6 whereby the outer part is free to slide upon and around the inner part
for a certain distance.
d d' are gaps or spaces in the tongues of sufficient size to permit of the
projections a and passing through them when the said gaps in the two parts are
brought opposite the projections for the purpose of disengaging the outer part

page_text: from the inner. The part a is provided with a lug e to which is secured by
screws e¹ one end of a metal band whose other end is brazed or otherwise fixed to
a lug e 2 formed on one of the projections 6' of the part b.
This band surrounds a brake drum g, Figures 2 & 5 fixed to the frame of the
machine on the inner side of the chain wheel. are lugs formed on the outer
part a to prevent the band opening out to its full extent, and which, when pressure
is brought to bear on the pedals, causes the band to act as a buffer so as to prevent
the parts coming together with a clash..
The parts occupy the position shown in Figure 1 during the forward pedalling
but when back-pedalling commences the motion of the inner part 6 is reversed
thus causing the two parts a and b to slide upon cach other and bringing the two
ends of the band nearer together whereby the latter is tightened around the fixed
drum and the brake thus automatically applied.
The whole of the parts may be contained in an ordinary gear case and forms a
very light combination chain wheel and automatic brake.
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. In chain wheels for velocipedes and other vehicles the use of an outer or
toothed part sliding upon and engaging with an inner or central part mounted upon
the crank axle, each of the said parts being respectively connected to the ends of a
spring metal band surrounding a fixed drum substantially as described and for the
purposes specified.
2. In chain wheels for velocipedes and other vehicles the combination of an outer
toothed part a formed with grooved projections a¹ and tongues a 2 having gaps d
and provided with lugs and a lug e to which one end of a metal spring band is
attached and an inner or central part 6 fixed to the crank axle c and formed with
grooved projections 61 and tongues 62 havings gaps d' the said part being provided
with a lug e 2 to which the other end of the metal band f is fixed, which band
surrounds a fixed brake drum g substantially as described and for the purposes
specified.
3. The improved chain wheel for velocipedes and other vehicles substantially as
described and shown in the accompanying sheet of drawings.
Dated this 9th day of January 1897.
J. B. FLEURET,
5 Hatton Garden, London, Agent for the Applicant.