Year: 1897

page_text: Date of Application, 28th June, 1897
Complete. Specification Left, 23rd Mar., 1898-Accepted, 20th May,
1898
I, JAMES BLACKLOCK HENDERSON, Doctor of Science, Teacher, of the Yorkshire
College, Leeds, in the County of Yorkshire, England, do hereby declare the nature
of this invention to be as follows:-
The object of my invention is to provide means whereby the turning moment
communicated from the crank-axle of a cycle to the driven wheel is more uniform
than in the case of the ordinary cycle gear and further to lessen the time taken
by the pedal to accomplish that part of its motion during which the action of
the feet is less effective.
To effect these objects in a rear-driven cycle I still maintain the chain and
circular sprocket wheels as in the ordinary gear but I transmit the turning moment.
from the cranks to the large sprocket wheel through a combination of links which
cause the cranks as they revolve to have a periodic back and forward angular
motion relatively to the sprocket wheel, of period one half that of the revolution
of the crank. By this means when the sprocket wheel is rotating uniformly,
the pedal moves round its circular orbit with varying velocity and the linkwork
is arranged to make the velocity greatest at those parts of the orbit in which the
action of the feet is least effective.
In one form of my invention I mount the large sprocket-wheel loose on the
crank axle and connect one of the cranks to one spoke of the sprocket wheel
through two links somewhat similar to the links of a cycle chain: To the middle
joint of these links when the crank revolves, I impart by means of an eccentric
an approximately simple harmonic motion of period equal to that of revolution
of the crank, and in such a manner that it produces a relative motion of the
extreme ends of the two links which is approximately simple harmonic in char-
acter but of half the period of the first simple harmonic motion.
In another form I mount a small toothed wheel on an axle fixed to a spoke of
the large sprocket wheel, the sprocket wheel itself being mounted loose on the
crank axle. I then connect the crank by means of a connecting rod to an eccen-
tric axle on this toothed wheel. As the crank revolves I cause the toothed wheel
to rotate on its axle by making it gear with a toothed wheel fixed to the cycle
frame concentric with the crank axle and of double the diameter of the first toothed
wheel. By this means when the sprocket-wheel revolves uniformly the crank
has an angular motion relatively to it, approximately simple harmonic in character
and of a period one half that of the revolution of the crank.
The gear is applicable to both front- and rear-driving cycles.

page_text: An Improved Cycle Gear.
I, JAMES BLACKLOCK HENDERSON, Doctor of Science, Teacher, of the Yorkshire
College; Leeds, in the County of Yorkshire, England, do hereby declare the nature
of this invention, and in what manner the same is to be performed, to be particu-
larly described and ascertained in and by the following statement :-
The object of my invention is to provide means whereby the turning-moment
communicated from the crank-axle of a cycle to the driven wheel is more uniform
than in the case of the ordinary cycle gear, and further to lessen the time taken
by: the pedal to accomplish that part of its motion during which the action of
the feet is less effective.
י
14.
7
To effect these objects in a rear-driven cycle I still maintain the chain' and'
circular sprocket wheels in the case of a chain driven cycle or the ordinary toothed
wheels in the case of a cycle driven by toothed gearing but I transmit the turning
moment from the cranks to the large sprocket wheel or the first gear wheel through
a combination of links which cause the cranks as they revolve to have a periodic
back and forward angular motion relatively to the sprocket or gear wheel, of
period one half that of revolution of the crank. By this means. when the sprocket
or gear wheel is rotating uniformly the pedal moves round its circular orbit with
varying velocity and the link-work is arranged to make the velocity greatest at
those parts of the orbit in which the action of the feet is least effective.
One mode of carrying out my invention is shown in Figs. 1 and 2.
Fig. 1 shows a front elevation of the arrangement.
Fig. 2 shows a sectional end elevation.
S is the sprocket wheel which is mounted on a bearing concentric with the
crank-axle and capable of rotating with reference to 0.
C is one of the cranks, both of which are fixed to the crank-axle Qin any; of
the usual manners.
i
"
E is an eccentric whose sheaf is rigidly fixed or connected to the frame. The
eccentric strap revolves on the sheaf.
h is a pin fixed to the crank C and projecting behind it.
하
g is a pin fixed to the eccentric strap in such a manner as always to revolve
with the strap round the crank-axle. 9 however may be capable of rotation on
its own axis relatively to the strap.
f is a pin passing through a hole in one of the spokes of the sprocket wheel S,
or otherwise attached to the sprocket wheel.
A is a link or system of links connecting the pins f and 7 so as to keep f
always the same distance apart.
and g
Bis a link or system of links connecting the pins g and h so as to keep g and h
always the same distance apart.
.
The turning moment is transmitted from the cranks through the links A and B
and the connecting pins f, g and h to the sprocket wheel S.
When the crank Crevolves, then the pin g is subjected to an oscillation in a'
radial direction relatively to the crank axle of approximately simple harmonic
nature and of period. equal to that of revolution of the crank. This imparts to
the pins f&h a relative motion of separation and approach of approximately
simple harmonic nature but of a period one half the period of revolution of the
crank.
Thus while the sprocket wheel S revolves uniformly the crank C is subjected
to a relative angular motion which causes its velocity to vary, there being two
points of maximum velocity and two of minimum in each revolution.

page_text: carries an eccentric connected by means of an eccentric strap with the crank, to
obtain the requisite relative angular motion of the crank and sprocket or gear
wheel, substantially as described.
1