Improvements in and relating to Gear Wheels.
Year: 1896

page_text: I, ROBERT OSBORNE COWAN, of Garden Villa, Bournbrook, Birmingham, in
the County of Warwick, Engineer, do hereby declare the nature of this invention
to be as follows:-
My invention relates to gear or chain wheels, and more especially to those
employed in the driving gear of velocipedes, and comprises certain improvements
hereinafter described in the method of cutting the teeth or wheel, so as to entirely
obviate or greatly reduce the friction at present developed between the latter and
the driving chain during work.
According to my said invention instead of forming the base or gap between the
teeth upon which surfaces the chain rests as true segments of a circle, I form each
of the said surfaces with a depression at the front of one tooth, and raise the said
surface higher at the back of the next tooth.
By constructing the wheels in this manner I find that the links of the chain lie
flat upon the surfaces between the teeth without setting up any, or any appreciable,
friction, instead of as occurs with gear or chain wheels cut in the usual manner
each link rotating upon the base of the tooth before coming into line with the said
surface, and thereby causing a very considerable amount of friction and wear of
both the chain links, and wheels.
A. F. SPOONER,
124 Chancery Lane, W.C., Agent for the Applicant.
Improvements in and relating to Gear Wheels.
I, ROBERT OSBORNE COWAN, of Garden Villa, Bournbrook, Birmingham, in
the County of Warwick, 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 :-
My invention relates to gear, chain, or sprocket wheels, and more especially to
those employed in the driving gear of velocipedes, and comprises certain improve-
ments hereinafter described in the method of cutting the teeth or wheel so as to
entirely obviate or greatly reduce the friction at present developed between the
latter and the driving chain during work.
In the accompanying drawing, which represents a side view of a chain or sprocket
wheel, I have shown how my said invention may be conveniently and advantageously
carried into practice.
a is the chain or sprocket wheel and b the teeth thereof. According to my said
invention instead of forming the bases or gaps b¹ between the teeth b, upon which
surfaces the chain rests, as true segments of a circle, I form each of the said

page_text: surfaces with a depression & at the front of one tooth, and raise the said surface
higher at the back of the next tooth as shown at 63, that is to say tangential to the
axis of the said wheel.
By constructing the said wheels in this manner I find that the links of the chain
will, when working, lie flat upon the surfaces between the teeth without setting up
any, or any appreciable, friction, instead of, as occurs with gear, chain, or sprocket
wheels cut in the usual manner, each link rotating upon the base of the tooth before
coming into line with the said surface, and thereby causing a very considerable
amount of friction and wear of both the chain links, and wheels.
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. A gear, chain, or sprocket wheel for the purpose of chain driving so formed
or shaped that the bases or gaps between the teeth are tangential to the axis of the
said wheel, substantially as and for the purpose specified.
2. The improved gear, chain, or sprocket wheel constructed substantially as
described with reference to the accompanying drawing.
Dated this ti dam of March 1007
A. F. SPOONER,
323 High Holborn, London, Agent for the Applicant.