İmprovements in Variable-throw Cranks for Velocipedes.
Year: 1896

page_text: Date of Application, 23rd Jan., 1896-Accepted, 2nd May, 1896
COMPLETE SPECIFICATION.
İmprovements in Variable-throw Cranks for Velocipedes.
I. LOUIS BOURZAC, of 39 Rue St. Eulalie, Bordeaux, in the, Republic of
France, Gentleman, 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 pedals for velocipedes, which consists
of an apparatus for differential pedal or pedals for giving more power of propulsion.
The differential pedal is composed of two winches or cranks, two elliptical levers
and two eccentric discs fixed to the two extremities of its axes which carries on
one of its sides the toothed wheel for receiving the endless chain destined for the
propulsion of a machine.
And in order that my invention may be thoroughly understood, I now proceed
to describe the accompanying drawing thereof, reference being had to letters and
figures marked thereon.
Fig. 1, is a front elevation of the elliptical lever and crank.
Fig. 2, is a side elevation.
Fig. 3, is a vertical section.
Fig. 4, is a section of the cone on line Y Ź.
Fig. 5, is an elevation of the cone.
Fig. 6, is a front elevation of the differential pedal.
Fig. 7, is a section on line A A.
Fig. 8, is an elevation of the winch and crank with the eccentric disc.
Fig. 9, is a section on line B B.
Fig. 10, is a view of Fig. 6, with the lever and pedal in a different position.
The winch or crank s as in Figs. 8, and 9, is composed of an arm on which the
pedal is fixed (at the point f) by means of a screw nut; on this arm there is a
notch g forming a slide or slides in which a pebble of ivory or metal moves on
balls supported or carried by the elliptical lever s, this arm terminates by an elbow
carrying an open collar or clamp i which is tightened by means of a screw j. This
collar moves by rolling on balls in the eccentric disc k represented with the winch
or crank.
The elliptical lever s is provided with a washer or hollow cylinder 7 used to fix
the pedal on the axle at the extremity of the axle hole, by means of a screw nut
and pin. At the extremity of the lever there is a turned or twisted pivot on
which the pebble / rolls or revolves in the notch or groove g of the winch or crank
above described. The elliptical levers is itself fixed by two metal screws at the
points n. n. Figs. 6, and 10, of the toothed wheel r to lead or force it away in its
movement of rotation.
The eccentric disc which is twisted and hollowed to tighten it, carries in its
diametrical line, a strengthening arm o on which, at the centre of the piece, there
is a threaded hole p. The said piece carries a second hole m on the same
diametrical line, which is screwed on the cone of the pedal. The limb of this
piece carries a throat or orifice which lodges the balls q on which balls the winch
or crank revolves, supported by its collar.
The differential pedal or pedaller has for its base, the principal of levers, of the
two which are employed in this mechanism, one, the elliptical lever, is, of a constant
or continuous length, the other, the winch or crank which solicits or urges the
preceding as regards the point of application of the power, lengthens itself at the.

page_text: moment when this application should happen. At this very moment the point of
support or fulcrum approaches itself to the resistance. We have therefore
lengthening of the arm of the lever for the power and a shortening of the arm of
the lever for the resistance of, a length equal to the lengthening or elongation as
follows:
Support or
fulcrum.
Resistance.
Power.
In the first case, the power is not necessary, because the pedal or foot rises. In
the second case (this is the moment when the foot leans or bears) the difference of
the levers being in an inverted or contrary direction, the necessary effort decreases
therefor in the proportion of this difference, the resistance remaining always the;
same.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, 1 declare that what I
claim is :-
1. In differential pedals for velocipedes, the combination of the opening f notch g
pebble threaded hole p axle hole m balls q hollow cylinder l screw j eccentric
disc and elliptical lever s, substantially as herein described and according to
Figs. 1, 2, and 3, of the accompanying drawing.
2. In differential pedals for velocipedes, the combination of the winch s¹ with
the opening notch eccentric disc k balls q open collar or clamp threaded
hole p axle hole m with screw j, substantially as herein described and according to
Figs. 8, and 9, of the accompanying drawing.
3. In differential pedals for veloripedes, the combination of the toothed wheel r
the elliptical levers balls 9 screw pebble h hollow cylinder 1 pius n threaded
hole p and screwed cone, with the axle hole m, substantially as herein described
and according to Figs. 4, 5, 6, 7, and 10, of the accompanying drawing.
Dated this 23rd day of January 1896.
J. P. BAYLY,
18 Fulham Place, London, W., Agent for the Applicant.