Improvements in Variable-throw Cranks, particularly adapted for Bicycles and like Vehicles.
Year: 1898

page_text: Date of Application, 10th Oct., 1893-Accepted, 22nd Apr., 1899
COMPLETE SPECIFICATION.
Improvements in Variable-throw Cranks, particularly adapted for
Bicycles and like Vehicles.
I, HENRY TAYLOR, of 221, Station Road, in the City of Belleville, in the County
of Hastings, in the Province of Ontario, Canada, Grocer, 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 improvements in crank drives more particularly adapted
for use in connection with the pedals of bicycles and like vehicles and the object
of the invention is to devise a form of crank drive whereby the greatest leverage may
be exerted upon the down forward stroke where the power is most rquired and
such leverage decreased to a minimum on the rearward upward stroke where the
power is least required and at the same time maintain the pedal in its rotation
in a true circular movement and it consists essentially of discs secured to the frame
of the bicycle on each side thereof and through which the pedal crank axle
extends eccentrically, horizontally on a line with and to the rear of the centre of
the disc, the pedal cranks being made in two parts, one part being securely
connected to the end of the pedal crank axle in such a manner that the other
part may reciprocate on it both to the front and to the rear of such pedal crank
axle, and the reciprocating portion of the crank being secured to a ring journal
on the periphery of the discs, the parts being otherwise constructed and arranged
in detail as hereinafter more particularly explained.
Fig. 1, is a perspective view of my improved crank drive as applicable to a
bicycle, one side only being shown.
Fig. 2, is a plan view of the crank drive complete on both sides of the frame,
the dotted and full lines indicating the forward and backward position of the
reciprocating portion of the pedal crank and pedal.
Fig. 3, is a side elevation showing various positions assumed by the pedal
crank.
In the drawings like letters of reference indicate corresponding parts in each
figure.
A are the journal discs secured to the frame B by suitable braces C or in any
suitable manner, so as to hold such discs rigidly to the frame. D is the pedal crank
F F are bars
axle journalled in suitable bearings in the hanger bracket E.
forming portion of the pedal crank and secured to the ends of the pedal axle,
such bars being of equal width or size throughout and being provided with
recesses f f between the inner side of same and the ends of the crank axle to
permit of the free reciprocation of the grooved bar G to and past the crank axle.
The grooved har G is preferably formed with a groove at its inside having
retaining loops g. I wish it to be understood that I lay special stress upon the two
portions of the crank being so arranged that the reciprocating portion may slide upon
the rigidly held portion past the crank axle as I am not aware of any device of a
similar nature in which this result is produced.
The advantage will be apparent as by such a construction I am enabled as will

page_text: hereinafter appear to maintain the rotation of the pedal H in a true circle. For
instance, it will be seen that the bar G is connected by a pin g¹ in the lug I
forming part of the ring J, which is journalled on the periphery of the disc as
shewn. The pin g' is of course revolubly held in the lug I and consequently this
clearly elucidates the point which I wish to make as hereinbefore set forth
viz. that the rotation of such pedal will be always in a true circle.
In the revolution of the extensible or reciprocating portion of each crank it will
be noticed that the outer end of the portion G of each crank will as the crank is
given its forward movement be beyond the free end of the bar F whereas when it
is at the centre of the rear portion of the stroke it will be within the free end of
the bar F.
The ring J has suitable bearings upon the periphery of each disc A, ball or
otherwise. A sprocket K is provided on the crank axle and such sprocket is
connected in the usual manner by sprocket chain to the sprocket pinion on the
main driving wheel.
The parts are connected and assembled in the following manner. The axle D
is formed in two halves one having a V-shaped notch and the other a V-shaped
projection designed to be brought together by means of right and left hand threads.
The journal discs A. are mounted in position one on each half of the pedal crank
axle D. The sprocket K is screwed on one half and both halves are then screwed
into the cone sleeve, which is previously adjusted in the bracket.
The discs A
are secured to the frame by means of the bracket C and the rings J are then
mounted on them, the balls in the bearings serving to hold the rings in place. The
grooved bar G is slipped over the crank F and secured to the ring J by the screw
pin extending through the lug I. The pedal is then screwed into the face of the
bar G opposite the pin gl.
Instead of the sprocket wheel K and the sprocket chain and sprocket pinion of
course any suitable form of drive from the pedal axle to the rear wheel axle may
be provided.
Again instead of attaching the bar G to the lug I forming part of the ring J by
a ping it is possible I may find it preferable to dispense with the pin g¹ and
attach the pedal axle rigidly in the lug I and allow it to extend through the bar G
far enough to form the axle of the pedal. In this construction it will be seen
that a suitable bearing would necessarily have to be provided in the bar G for
the axle. This construction I find in practice would avoid the tortion incident to
the other construction hereinbefore described and I wish it understood that I
lay claim to this equivalent construction.
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. In a crank drive, the combination with the revoluble axle and disc rigidly
mounted near the end thereof and eccentric thereto, a ring having a suitable
bearing on the disc, a bar secured on the end of the axle and of equal size through-
out, a bar slidably held upon the aforesaid bar and so arranged as to reciprocate
freely diametrically past the axle, a pedal or impelling device on the end of the
reciprocating bar, a pin opposite the centre of the pedal revolubly connecting such
bar to the ring whereby such pedal is maintained in its revolution in a true circle
as and for the purpose specified.
TX
.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London,
Agents for the Applicant.