Year: 1894

page_text: Date of Application, 12th Dec., 1894
Complete Specification Left, 9th Sept., 1895-Accepted, 26th Oct., 1895
1 JAMES TURNBULL, Engineer 14 Plumstead Road Plumstead Kent do hereby
declare the nature of this invention to be as follows:-
A method of applying the action of a crank so that the leverage of action applied
to the machine it is driving shall be greater than the length of crank. This is
applicable to bicycles engines or other machinery.
The centre of crank shaft is eccentric to the main shaft of engine, or in case of a
bicycle, to the chain wheel of the bicycle, but shall lie within the limits of their
circumference.
The crank drives the machine by means of a connection which will slide or roll
in or on horns or arms projecting from shaft or wheel that is to be driven.
The crank will be so fixed as to obtain the greatest leverage of the horns at the
moment the driving power has its greatest effect on the crank. In cases where the
machine driven is a bicycle, or a machine that is similarly driven, the crank will
be a double one, having its ends radiating in opposite directions, with crauk shaft
in the middle, the extreme ends to be connected as above, with the horns radiating
from shaft or wheel to be driven.
JAMES TURNBULL 14 Plumstead Road Plumstead Engineer and Bicycle Maker
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 :--
As shown on drawing to be applied to a bicycle; it consists of a double crank a
with sliding, ball, or roller races b b-hereafter called races-which is attached to
crank shaft c in the ordinary way. The other end of the crank shaft will have an
ordinary crank fitted on in the usual manner (not shown). A. chain wheel or ring d
is set eccentric to crank shaft c and runs on bails or rollers ee which are attached
to a fixed centre piece f. The chain wheel connects with the crank a by means
of slides, balls, or rollers-hereafter called rollers g', g² g³ which are attached to
3 horns or arms h, set equidistant round chain ring d. The action is as follows,
The crank being in horizontal position as shown on drawing, with roller g³ in
crank race the crank is moved by pedal (not shown) attached to boss i of crank a
in a downward direction till it assumes the perpendicular position shown by dotted
lines, by which movement the roller gl has engaged in crank race and assumed the
position shown by the top dotted roller, while roller g' has assumed the position
shown by the bottom dotted roller.
The movement of the crank being continued in the same direction (by pressure
on crank at other end of crank shaft) the roller moves to the position of g³ and g³

page_text: has attained the position g' ready to engage in race at pedal end of crank. which
has now assumed a horizontal position and is rising to the top."
Thus each revolution of the crank produces a two. thirds revolution of the chain
ring d.
As an alternative the crank may bear the rollers, and the horns may constitute
the races.
On the drawing the centre piece f is shown to be fixed by bolt k also if
necessary to bearing of crank shaft.
To apply the invention to engines or machinery it is only necessary to substitute
main shaft or spindle for chain ring the crank shaft being. run on independent
bearings.
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.
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;
..:
1
1. The division of chain wheel or shaft into three equal. parts, so that each
stroke of the crank produces revolution of chain wheel or main shaft, as the case
may be.
2. Horns of arms attached to chain wheel or shaft, and projecting beyond their
diameter and engaging in crank.
3. The institution of sliding or rolling races on cranks or horns as above.
described.
4. The engagement and disengagement of crauk with chain wheel or shaft as
above described.
5. Constitution, of chain ring instead of chain wheel and running on balls or,
rollers as above described.
Dated this 9th day of September 1895.
JAMES TURNRILL