Improvements in Driving Gear for Velocipedes and the like.
Year: 1896

page_text: Date of Application, 22nd May, 1896
PROVISIONAL SPECIFICATION.
Improvements in Driving Gear for Velocipedes and the like.
I, JOHN TOURTEL, of 17 Sinclair Mansions, West Kensington Park, in the County,
of London, Engineer, do hereby declare the nature of this invention to be as
follows:-
My invention relates to improvements in driving gear for velocipedes and the like
and inore particularly refers to driving gear in which compound cranks are employed
for the purpose of enabling a greater leverage to be obtained during the downward
than during the upward movement of the pedal.
Whereas it has hitherto been generally found necessary in driving gear of this
description to employ a slide (either fixed upon the crank shaft with the crank
arranged to slide through it or sliding upon a crank fixed to the crankshaft) and
whereas the lengthening and shortening of the distance of the pedal from the crank-
shaft has usually been effected by the action of an eccentric lever or cam which
causes the slide to move upon the crank when the crank is fixed and the slide
moveable or causes the crank to move within the slide when the slide is fixed and the
crank is moveable. Now my invention consists in improvements in the construction of
such driving gear whereby the slide is rendered unnecessary and the gear is made
simpler and more effective.
I fix upon each end of the crankshaft a crank the free end of which crank is,
provided with a long slot or groove and I attach to the frame of the velocipede
an eccentric disc or cam provided with an eccentric strap. Upon the said eccentric
strap or an extension thereof I mount a long pin which I arrange to project'
through the slot in the crank and upon the outer end of the said pin I place the
pedal. In order to prevent the said pin from causing friction in moving backwards
and forwards in the slot of the crank I place within the said slot and mount
loosely upon the said pin a roller which is thus free to roll in the slot. Where
it is found desirable to still further reduce the friction I provide the said roller with
suitable ball bearings.
Dili: Thanty around day of May 1896
COMPLETE SPECIFICATION.
Improvements in Driving Gear for Velocipedes and the like.
1, JOHN TOURTEL, of 17 Sinclair Mansions, West Kensington, in the County of
London, 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:-
My invention relates to improvements in driving gear for velocipedes and the like
and more particularly refers to driving gear in which compound cranks are employed
for the purpose of enabling a greater leverage to be obtained during the downward
than during the upward movement of the pedal.

page_text: Referring to the accompanying drawing, Figure 1 is a plan, Figure 2 an
elevation, Figure 3 a part plan, and Figures 4, 5 and 6 detail sections of the
apparatus according to my invention.
A is the ordinary bearing for the driving shaft B upon which shaft is fixed
the sprocket wheel C. D D are slotted cranks fixed at right angles to each other
upon the shaft B. Eccentric sheaves such as E are secured by clamps such as F
to the frame of the velocipede, and upon these sheaves are mounted straps G G
having extension pieces g g' to which are fixed the treadle pins H. H'. The said
treadle pins are arranged to pass through the slots of the cranks D D' and bear upon
their outer ends the treadles h h'.
The effect of this arrangement is to cause the distance between the shaft B and
the treadle pins to be varied during the rotation of the said shaft, thus varying
the length of the cranks, in such a manner that the longer leverage is obtained
in the downward movement of the foot, as at the point X, and the shorter leverage in
the upward movement, as at the point Y, Figure 2.
The apparatus so far described is well known, but has hitherto been impracticable
owing to the friction caused by the treadle pin (or by the slide which is sometimes
provided upon the treadle pin) sliding in the slot of the slotted crank.
To overcome this difficulty, I provide upon that portion of the treadle pin which is
contained within the slotted crank a roller or sleeve K, and in the space between the
said sleeve and the treadle pin I place balls or rollers such as are shown at L
(Figures 3, 4 and 5) and by this means I am enabled to reduce the friction to a
minimum.
The eccentric sheaves and straps are usually provided with balls such as M so as to
prevent friction, and in order to protect these balls from dust, I provide a flange or
ring N on either side of the strap, as shown in Figure 6.
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:
1. The improvement in driving gear for velocipedes and the like substantially as
described with reference to the drawing.
2. In a compound crank driving gear having a slotted crank D, eccentric E,
strap F, and treadle pin H, the employment of a roller or sleeve K having roller or
ball bearings substantially as described and illustrated in Figures 3. 4 and 5.
Dated this Eighteenth day of February 1897.
JOHN TOURTEL.