AN IMPROVEMENT OR IMPROVEMENTS IN TRICYCLES AND OTHER VELOCIPEDES
Year: 1880

page_text: PROVISIONAL SPECIFICATION left by George Illston at the Office of
the Commissioners of Patents on the 15th October 1880.
GEORGE ILLSTON, of Birmingham, in the County of Warwick, Manufacturer.
"AN IMPROVEMENT OR IMPROVEMENTS IN TRICYCLES AND OTHER VELOCIPEDES."
My Invention has reference to those parts of tricycles and other velocipedes by
which the motion of the treadle axle is cominunicated to the driving wheels; and
my said Invention has for its object to effect the transmission of the motion of the
treadle axle equally to the two driving wheels when the tricycle or velocipede is
moving in a right line, and to permit the driving wheels rotating at different
speeds when the tricycle or velocipede is travelling in a curve.
I will describe my Invention in connection with a tricycle.
I construct and arrange the parts of a tricycle to which my Invention relates in
the following manner :-Instead of fixing the driving wheels on the ends of the
same shaft, I fix only one of them to the shaft, and fix the other on a tubular shaft
or sleeve working loosely upon the shaft. The shaft carries a grooved chain wheel
near its middle, and the inner end of the tubular shaft or sleeve carries a similar
grooved chain wheel. The said grooved chain wheels are symmetrically situated
on each side of the middle of the axle, and at a short distance from the middle of
the axle. Between the said grooved chain wheels the ordinary chain wheel is
situated, the bush of the said chain wheel turning freely on the axle and between
the grooved chain wheels described. Between the spokes of the chain wheel, and
in the same plane as the wheel, two short axles are situated, the said axles turning
in bearings in the said spokes. The said axles are situated in the same line, the
line being parallel to a diameter of the wheel, that is, being a chord to the periphery
of the wheel. Each of these short axles carrries a small grooved chain pulley.
An endless chain or chain band passes over the grooved chain pulleys and the
small grooved chain pulleys, gearing the said four pulleys together. The action of
the parts is as follows:-When the tricycle is travelling in a straight line the
motion transmitted from the cranked axle to the ordinary chain wheel is trans-
mitted equally to the small grooved chain pulleys carried round with it to the two
grooved chain wheels connected respectively with the driving wheels, and there is
no travelling of the chain band upon the said grooved and small grooved chain
nulleys.

page_text: When however the tricycle is directed into a curvilinear path, and one of the
driving wheels rotates at a velocity different from that of the other, the chain band
travels upon
the said grooved chain pulleys at a rate dependent on the difference
between the rotary speeds of the two driving wheels, and while communicating
rotary motion to them permits them to rotate at different speeds. When the tricyole
returns to a rectilinear path the travelling of the chain band on the grooved chain
pulleys ceases, and the driving wheels rotate at the same speed.
My Invention is applicable to all velocipedes having two driving wheels.