Improvements in Crank Driving Gears.
Year: 1895

page_text: Date of Application, 8th Apr., 1895-Accepted, 11th May, 1895
Improvements in Crank Driving Gears.
I, JACOBUS JOHANNES VAN OORDE, of Arnheim, in the Kingdom of Holland,
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 :-
In the known arrangements for converting the motion of treadle cranks into the
rotary motion of a driving shaft, the treadle cranks and the feet of the operator,
describe a circular path with a leverage of crank remaining always the same, but
of which only about two-fifths can be effectively utilized, whilst the remaining
portion of the movement of the feet is useless or non-effective.
Now the present invention has for its object to lengthen the effective path and
to shorten the path that has to be described without work being done, whilst
making the leverage of the crank as long as possible during the travel over the
effective path, and making it as short as possible during the non-effective path,
thereby effecting a very favourable result. This invention may for example be
applied to small machine tools, but is particularly suitable for driving cycles.
In the accompanying drawing two arrangements of the new apparatus are
illustrated, Figures 1 and 3 being side elevations, and Figures 2 and 4 front.
elevations partly in section-of the two arrangements.
The principle of the present invention consists in guiding the treadle cranks in
a circle eccentric to the driving shaft, whilst a pin fixed on the treadle crank
slides in a crank link fixed on the driving shaft, so that the said pin acts upon the
link at the greatest distance from the driving shaft, that is to say, acts with the
longest crank leverage when the axes of the driving shaft of the treadle crank
circle and of the aforesaid pin are situated behind one another, whilst the crank
leverage is smallest when the axes of pin of the driving shaft and of the treadle
crank are situated behind one another. It will be readily understood that in this
case the arrangement may be such that the longest crank leverage is employed
for the downward movement of the feet, and the smaller crank leverage for the.
upward movement.
Referring to Figures 1 and 2 of the drawing, a is the ordinary bearing for the
axle 6 on which is loosely mounted the chain wheel c. Upon the shaft b is keyed
a crank d, about whose pin d' the treadle crank e is capable of rotating. On the
end of the crank e is fixed a pin f on one end of which is mounted the pedal and
the other end of which slides in a slot g in a crank link connected with the chain
wheel c either directly or indirectly, whereby the rotation of the crank e is
transmitted to the chain wheel c.
In the modification shown by Figures 3 and 4, the chain wheel n is keyed upon
the driving axle m and is embraced by a stirrup i carrying a bearing for the end
of the axle m to which is fixed an eccentric disc k which fills the place of the
support d of the first arrangement. Around this disc an eccentric strap / is
mounted and carries a pin f¹ adapted to slide in a slot g¹ in a crank link h¹ fixed on
the end of the driving axle m. The pin is extended to form a pedal pin on
which the pedal is mounted.
I wish it to be particularly understood that I do not limit myself to the precise
details of construction herein before described and illustrated by the accompanying
drawing, but that I hold myself at liberty to make such changes and alterations
as fairly fall within the spirit and scope of my invention.

page_text: 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 crank driving gears, substantially as hereinbefore
described and illustrated by the accompanying drawing.
2. An apparatus for converting treadle crank motion into the rotary motion of a
driving shaft, the arrangement being such that the treadle cranks e and I are
guided in a circle eccentric to the driving shaft, and engage by means of a fixed
pin fand in a crank link fixed on the driving shaft, in such a manner that the
crank leverage is increased on the downstroke and is shortened on the upstroke, as
set forth.
Dated this 8th day of April 1895.
ROBERT E. PHILLIPS, Assoc. M. Inst. C.E., M.I. Mech. E.,
Consulting Engineer and Patent Agent,
70, Chancery Lane, London, W.C., Associate Agent.