improvements ІЦ CrankS.
Year: 1894

page_text: Date of Application, 27th Nov., 1894-Accepted, 12th Jan., 1895
improvements ІЦ CrankS.
A communication from HENRI FARJAS, of 42, Boulevard Bonne Nouvelle, Paris,
in the Republic of France, Engineer.
I ALFRED JULIUS BOULT of 323 High Holborn, in the County of Middlesex
Chartered Patent Agent, 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 :-
This invention relates to a new kind of extensible pedal specially applicable to
pedals of cycles and other apparatus worked by the feet, and by means of which
my correspondent obtains au increase in suppleness in the working i.e. less fatigue
and at the same time an automatic and progressive augmentation of the lever-arm
at the time of the effort.
Further, for the better understanding of this invention my correspondent shows
it on the accompanying drawings, wherein
Fig. represents in elevation a pedal for a safety bicycle or bicyclette provided
with extensible cranks of this system;
Fig. 2 shows a plan of the same;
Fig. 3 is a perspective view of an extensible crank with a modification in the
controlling spring.
Figs. 4 and 5 are an elevation and plan of another kind of pedal with extensible
cranks.
Fig. 6 is a modification of the crank shown in Figs. 4 and 5.
This system consists simply in constructing each crank in two parts M and N,
jointed to each other, the latter N carrying a pedal P of any type whatever.
Around the pin T, which forms the joint between N and M is mounted a coiled
spring R whereof one end is secured to the crank M and the other to the connecting
rod or crank-extension N.
The action of this device will readily be understood.
The cranks, when in a state of rest, occupy the position shown in hard lines
in Fig. 1. But, when running, the cyclist pressing upon the pedal P. the spring R
is compressed and the link or crank-extension N may assume any position between
the said position of rest and that shown in dotted lines in the same figure,
depending upon the intensity of the effort.
It will thus be easily seen that the length of the crank will increase with the
effort applied and the compression consequently applied to the spring R, and that,
therefore, the useful effect produced by the cyclist's foot will be more considerable
than that with any other kind of crank at present employed.
Consequently, fatigue is lessened and the sides rise with greater facility.
For the rest, the power of the spring must be such that on level ground or a
descending slope, its action is little or nothing, but that, on the contrary, when
running up an ascending slope it is compressed by the pressure of the foot, and so
much the more as the inclination increases. The length of the crank is therefore
automatically proportioned to the steepness of the slope to be mounted.
As shown in Fig. 3, the spring R, whether enclosed or not in a case, can be
replaced by a coiled spring r acting by extension, as shown in Figs. 3 and 6, or by
compression or simply by a rubber spring which fulfils the same purpose and is
elongated by pressure on the pedal.

page_text: In Figs. 4 and 5 my correspondent somewhat modifies the construction of the
pedal, without however affecting the principle of the extension of the cranks.
The pedal P' and the link N₁, at their lowest point, are below the joint Tat the
outer end of the crank M' instead of being above or on the same level therewith
as in Figs. 1, 2 and 3. As will easily be seen, from the dotted lines in Fig. 4, the
lever-arm is lengthened, as before, by the pressure of the foot and an exactly
similar result is obtained.
In Fig. 6, similarly as before the spring R¹ is replaced by a coiled spring r¹ or a
rubber spring.
In all cases, my correspondent limits the displacement-angle between the link N
and the crank M either by giving the joint T the form of a knee-cap fitted with
shoulders a, b, c (Fig. 3) or by pins g g¹ (Fig. 6), or by any suitable means.
Having now particularly described and ascertained the nature of the said inven-
tion, as communicated to me by my foreign correspondent, and in what manner the
same is to be performed, I declare that what I claim is;—
An extension-crank for bicycles and other apparatus worked by the feet composed
of two parts such as M and N jointed together in such a manner that the crank is
lengthened at the moment when the foot presses upon the pedal and that the
movable part N is brought back to its original position as soon as the pressure
ceases by a spiral coiled or other spring substantially as described and illustrated in
'the accompanying drawings.
Dated this 27th day of November 1894.
BOULT & WADE,
Agents for the Applicant.