Improvements in Pedal Mechanism for Propelling Bicycles.
Year: 1897

page_text: Date of Application, 13th Apr., 1897-Accepted, 19th June, 1897
COMPLETE SPECIFICATION.
Improvements in Pedal Mechanism for Propelling Bicycles.
I, WILLIAM SAMUEL SHARPNECK of No. 4 South Elizabeth Street Chicago in the
State of Illinois of the United States of America, Civil Engineer, 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 :-
The invention relates to pedal mechanism for applying power in propelling
bicycles; and the object of my improvement is to provide suitable means for
connecting the pedal mechanism with the spindle of the wheel in connection with ball
bearings for the spindle in the frame.
I attain this object by the means illustrated in the accompanying drawings
in which-
Figure 1 is a side elevation representing a fragment of the frame and drive wheel
of a bicycle provided with my invention.
Figure 2 is a fragment of a horizontal section taken partly on the line of the axis
of the spindle of the drive wheel and partly on a higher line so as to show one of the
pedal levers in plan view and the other and its connection with the spindle in
sectional view.
Figure 3 is a detail showing an enlarged sectional view on the line 3-3 of
Fig. 2.
Figure 4 is a detail showing a fragment opposite to the line 4-4 of Fig. 1 in
sectional elevation.
In the drawings A designates the drive wheel, B the frame, C the pedal levers,
D racks and E pinions. The spindle a of the drive wheel journalled in the frame
at a' (Fig. 2) and provided with ball-bearings. A sleeve, having a polygonal part a²
for applying a wrench, is threaded upon the spindle at each end and has its inner
extension a³ made conical to form an adjustable counter part of the ball-bearing. It
has a reduced cylindrical extension at in the outer direction which forms the bearing
for the pinion and is made of hardened steel. The bore of the pinion is provided
with eccentric pockets e in which are placed hardened rollers e¹. The rollers come
between the reduced cylindrical extension and the eccentric bottom of the pockets
and are pressed by elliptical springs e² toward the shallow part of the pockets so as
to bind and form a clutch which fixes the pinion to the sleeve for rotation in the
forward direction but leaves it free to revolve upon the sleeve in the backward
direction. The pinions are made of hardened steel and have rings e³ of softer metal
shrunk upon their ends and preferably projecting beyond the outer line of the cogs to
form guides for the rack, the purpose being to aid in preventing any lateral movement
of the pedal levers. The extreme extension of the spindle is reduced and threaded in
the opposite direction from the other part so that a jam-nut E' applied thereto can
be made to secure the sleeve, keep the pinion in its placo thereon and close the outer
ends of the roller pockets, the other ends being closed by the shoulder at the juncture
of the polygonal part with the reduced cylindrical part of the sleeve.
The pedal levers are pivotally mounted on the frame at opposite sides in advance of
the drive wheel by means of pios c attached to the horizontal bar and provided with
ball-bearings c, the pins being preferably supported at their outer ends by means of
brace pieces C connecting them with the upper part of the frame to avoid torsion.
The part of the levers behind the pivotal mounting forms a yoke (to which the ends
of the rack are connected and the lower members of the yoke, striking the pinions,

page_text: operate as stops to the down movement of the fore part of the levers. A walking
beam F is pivotally mounted on a bar F¹ of the frame and has one end connected
with each of the pedal levers, at a point in front of their connection with the frame,
by a flexible cable, or preferably telescoping rod G, whereby the power applied to one
of the pedal levers to force it down will cause the opposite one to be correspondingly
raised.
The front end of the levers is curved upward in order to elevate the extreme end so
that the pedals I can be centrally mounted on the levers and brought nearer together
than pedals mounted on cranks. The pedals have ball-bearing connection with the
pedal levers.
The front part of the levers is made in sections the end of each section being
provided with an eye c² and set screw whereby the leverage can be shortened or
lengthened for increasing or slackening the speed. The mechanism is designed to
drive the wheel forward only and in this use the rods G are subject to a pulling strain
only, but an attempt to run the wheel backward would put a thrust upon said rods
liable to bend them if rigid, therefore they should be made to telescope or a cable or
chain should be used in order to avoid liability to breakage in case of misuse or
accidental running of the wheel backwards; and to further protect the wheel in this
regard provision is made at the top of the racks by providing sufficient space between
the upper members of the yokes and the toothed part of the racks to permit the
pinions to run off the toothed parts and thus be thrown out of gear in case of
prolonged running of the wheel backward. The rack and pinion cannot be thrown
out of gear in the regular operation because the stop of the lower member of the yoke
with the pinion on one side of the wheel, through the connections of the rods G, is
timed to check the motion of the yoke on the other side before the pinion runs off the
rack at its upper end.
Having now particularly described and ascertained the nature of said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :
1. The combination with a ball-bearing in a wheel frame of the wheel spindle
provided with sleeves threaded thereon at opposite sides of the ball-bearing and
having conical extensions on their inner ends and cylindrical extensions on their
outer portions, a pair of pinions adapted to the cylindrical extensions, clutches adapted
to fix the pinions on the cylindrical extensions in the forward rotation and free them
thereon in the backward rotation, a pair of pedal levers mounted on the frame and
connected with one another to work in unison, and a pair of racks connected with the
pedal levers and adapted to engage the pinions as specified.
2. In a pedal mechanism for bicycles the combination with the driving spindle of
a sleeve threaded thereon and having a polygonal part with a conical extension on
one side and a reduced cylindrical extension on the other side, a pinion having its
bore fitted on the reduced cylindrical extension, a clutch adapted to fix the pinion to
the sleeve in the forward rotation and to free it therefrom in the backward rotation
and means for securing the pinion from displacement on the sleeve as specified.
Dated this 13th day of April 1907
WILLIAM SAMUEL SHARPNECK,
By H. J. Haddan,
18, Buckingham Street, Strand, London, W.C., Agent to Applicant.