Improvements in Driving Gear for Cycles and the like.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
Improvements in Driving Gear for Cycles and the like.
1, JAMES HOWARD, of 47, Morton Street, Pimlico, London, S.W., Manu-
facturer, do hereby declare the nature of this invention to be as follows:-
This invention relates to improvements in driving gear for cycles and the like,
and has for object to facilitate the working of the mechanism by lessening
the expenditure of muscular energy required on the part of the rider of the
machine, thereby enabling him to attain a higher speed and maintain the same for
a longer period than has hitherto been the case with driving mechanism of known
.
constructions.
In carrying out my invention in practice I provide on the crank axle, instead
of the usual circular sprocket wheel, an elliptical sprocket wheel, the deviation in
said ellipse from the true circle being determined according to requirement. On
or over the elliptical sprocket wheel I place a bifurcated lever device, pivoted
and running free in suitable ball bearings on the crank axle, and having at
the extremities of both arms suitable small sprocket wheels adapted to engage with
the driving chain at suitable points between the crank axle and the chain wheel
mounted on the spindle of the driving wheel, for the purpose hereinafter described.
In order to increase the strength of the lever device the extremities of both forks
may be connected by a stay rod or the like.
At the ends of the crank axle the pedal cranks are mounted in the usual
fashion. The manner of working of my improved driving gear is as follows.
It is obvious that in rotating the elliptical sprocket wheel in the usal manner
by pedalling, the larger and smaller diameter of the ellipse continually change their
direction from the vertical to the horizontal and so on through all the degrees
of the circle. The distance between the upper and lower portions of the driving
chain near the sprocket wheel, therefore, also.continually varies in accordance with
the relative momentary directions of the larger and smaller diameters of the said
sprocket wheel and in consequence thereof the tension of the driving chain will at
certain moments be greater than at others. When the chain is thus slackened the
slack"
"will immediately be taken up and equalized by the hereinbefore described
small sprocket wheels provided on the arms of the bifurcated lever device, and the
upper or "pulling" portion of the driving chain exercising the greater pressure
on the small sprocket wheel attached to the upper arm of the lever, will tend to
depress the lower arm of said lever device and transmit, through the small sprocket
wheel, engaged with the lower portion of the chain, the forward movement of the
upper chain portion to the lower portion, causing the latter to aid in the working
of the mechanism instead of running loose as has hitherto been the case.
66
Dated this 8th day of April 1897.
HUGHES, ELI & HUGHES,
For the Applicant.

page_text: Improvements in Driving Gear for Cycles and the like.
I, JAMES HOWARD, late of 47, Morton Street, Pimlico, London, S.W., but now
of 2, Sandfield Terrace, Guildford, in the County of Surrey, England, Engineer,
do hereby declare the nature of my said invention and in what manner the same is
to be performed, to be particularly described and ascertained in and by the
following statement:-
The invention relates to means for taking up the slack of driving chains when
used with illiptical chain wheels, such slackness of the chain occurring when the
longer axis of the ellipse is in a horizontal position.
And in order that my said invention may be particularly described and ascer-
tained, reference is hereby made to the accompanying drawings, in which similar
letters of reference indicate corresponding parts.
Fig. 1 is a front elevation of an elliptical chain wheel fitted with my improved
means for taking up the slack of the chain.
Fig. 2 is a sectional plan view of same.
Figs. 3 and 4 are diagrams serving to illustrate the action of the improved
apparatus.
According to my invention I provide a triangular frame a suitably mounted
loosely on the boss 6 of the elliptical chain wheel c or on the axle d, in such
a manner that the chain wheel c and the axle d are free to revolve in bearings
in the crank bracket e without causing a similar action on the frame a, which
remains in position between the forward and backward moving portions of the
chain f, Figs. 3 and 4.
The frame a. is provided with a small chain roller or wheel g. suitably mounted
on ball bearings and is also provided with a short arm h. carrying a small chain
guide wheel gl. also mounted on ball bearings. The short arm h. is pivoted to the
frame a at i, the short arm h being controlled in its movement by a coil spring in
the box k which is arranged to exert its power outward and against the underside
of the chain. The motion of the short arm is limited by a pin 7, fixed in the
frame a within the recess m, formed in the short arm h. The elliptical wheel
may be set at any angle relatively to the cranks as desired, and may be constructed
on any of the well known detachable chain wheel principles.
The action of the frame and its wheels g g' is illustrated by the diagrams,
Figs. 3 and 4. When the longer axis of the ellipse is vertical the spring in the
box is compressed or wound up, the chain f running over the wheels g and g¹
freely between the chain wheels c and n. When the longer axis of
the ellipse is horizontal, the short arm h is forced outward by the
spring whereby the slack of the chain is taken up, the spring also forcing
the arm h to assume its relative position at all other points of the revolution;
the frame a also accommodates itself to the action of the small wheels .g, g¹.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is
1. The improved means for taking up the slack of driving chains when used
with an elliptical chain wheel, constructed, arranged, and operating substantially
as described and illustrated by the drawings.
2. In means for taking up the slack of driving chains as aforesaid, the
application and use of a frame, loosely mounted on the crank axle or on the boss
of the chain wheel, and carrying two idle chain wheels; one of such idle wheels

page_text: being mounted in ball bearings direct on the frame, the other being mounted
in ball bearings on a spring controlled short arm pivoted to the frame, sub-
stantially as set forth.
3. The method of automatically taking up the slack of driving chains when
used with an elliptical chain wheel, consisting of a vibrating frame carrying two
idle chain wheels the distance between which is capable of expansion and con-
traction according to the position of the elliptical chain wheel, substantially as
described.
Dated 10th Janu
1000
GEORGE DOWNING & SONS,
8, Quality Court, London, W.C., Agents.