Improvements in Chain Gearing.
Year: 1896

page_text: Date of Application, 26th May, 1896-Accepted, 13th June, 1896
COMPLETE SPECIFICATION.
Improvements in Chain Gearing.
HERBERT LUZERNE TODD, Electrician, 44 Upper Tollington Road, Holloway,
N. London and FREDERICK WILLIAM MCCLELLAN Clerk, Lincoln House,
Astey's Row, Canonbury N. London, 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 consists of a toothed wheel for carrying the chain and a stationary
piece fastened to the frame to gradually increase the radius of the pull of the
chain on the sprocket wheel for the purpose of increasing the power or speed.
To accomplish this we propose to have the sprocket wheel so made that the teeth
shall be farther apart at the periphery than the length of any one link in the chain
so that the tooth when entering the chain will not touch the back part of the link
until the tooth has arrived at that portion of the wheels revolution where the
pressure would be necessary and prior to the preceding link leaving the wheel.
The stationary piece to be a circular disk with opening for the axle of the wheel
placed at one side of the centre and so fastened to the cycle frame that the long
side of the disk will be at the point of the wheels revolution where the links of the
chain are to pull upon the teeth of the wheel. To more fully explain this invention
reference is made to the accompanying drawings in which like letters represent
similar parts.
Fig. 1. is a side elevation.
Fig. 2. is a rear view.
In Fig. 1A is the sprocket wheel, B. is the disk, C. the chain, D. the axle.
The chain in being pulled round in the direction of the arrow allows of the
tooth 1. to cuter the opening in the link 10 of the chain without touching the back
pin of the link and the tooth and link successively take the positions as shown at
numbers 10 to 17 inclusive. When the tooth has arrived in the position as at 15,
then the back of the link has come in contact with the tooth No. 6 and as the
chain advances, pulls the wheel around until the succeeding tooth No. 5 has come
in contact with the next link and pulls upon the tooth No. 5 just as the link No. 16
is about to leave the wheel as at No. 16. And as the circumference of the
stationary disk is smaller than the sprocket wheel and set as described, one link in
the chain is gained for each revolution of the sprocket wheel; thus giving a
complete turn of the sprocket wheel with one link less than ordinarily used. Thus
if in the sprocket wheel there were eleven teeth, as in the drawing, the same
leverage upon the sprocket would be obtained as if the sprocket was of the
diameter of the larger side of the disk and contained 12 teeth and the links of the
chain to cover the sprocket on the binding side or one half of its circumference
was six of greater length.
It is obvious that if the links in the chain are shorter than the distance in the
sprocket wheel teeth and the chain is used only at and from the link No. 10
to No. 16 that for every revolution of the propelling wheel the chain will do as
much more work on the sprocket as the difference in the semi-circumference of the
sprocket and the semi-circumference of the disk. The stationary disk could also
be supplied with small wheels for the chain to roll over and the chain may be of
any shape or form so long as the space in any one link is long enough to admit of
the movement as described.

page_text: Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :
1. In a sprocket wheel the combination of a toothed wheel to carry a chain for
cycles, the teeth of which are farther apart than the length of any one link of the
chain, a circular disk eccentrically placed and fastened to a cycle frame as and for
the purpose set forth.
2. In a sprocket wheel for cycles the combination of a wheel to carry a chain
and a stationary disk eccentrically placed, said disk to have rollers for the chain
to run on, and attached to the frame of a cycle as and for the purpose specified.
Dated this Twenty-sixth day of May 1896.
HERBERT LUZERNE TODD.
F. W. MCCLELLAN.