variable-throw Crank for Cycles.
Year: 1896

page_text: Date of Application, 28th Mar., 1896-Accepted, 30th May, 1896
variable-throw Crank for Cycles.
EDWARD MATTEI M.R.C.S. Eng. 9 Keppel Street Russell Square W.C.
London 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 purpose of this invention is to diminish the length of the pedal lever of a
velocipede during its upwards and backwards sweep whilst giving sufficient
leverage during the forward and downward stroke.
That purpose I attain by combining the action of the following pieces made of
steel which though described as single should be understood to be in pairs, one for
each side.
1st. The lever should be of a rectangular section of one inch by three quarters
of an inch and about eleven inches long.
2nd. The sleeve which is fixed by screws on a flat rectangular piece carrying
on the middle of one side a square cap to fit one end of the driving axel i.e. the
axel which carries the driving cogwheel. This piece is meant to rotate with the
lever inside which the latter slides when revolving. The sleeve should be about
three inches long.
3rd. The rails are rods, rectangular in section of one third by one quarter of
an inch, and the length they should be will be gathered on further description.
They should be curved into an arc of a spiral and firmly fixed to the frame of the
cycle in a position just inside, and around and over the circle described by the
rotation of the sleeve.
One end of the rail which should be bevelled and which for purposes of
description will be called the near end (being fixed nearer to the centre of
rotation) should correspond to the uppermost point which the sleeve reaches
without the two coming into contact. The rails thence form an arc with gradually
increasing radii from the centre of rotation till they stop at a point underneath
diametrically opposite the near end.
Having so far mentioned the several pieces which enter in the formation of
this contrivance, I now give a more detailed description of them.
The lever should fit into the sleeve with the smaller sides of its section looking
forward and backwards. The ends of it should remain outside the sleeve. Each
end, on the side facing the cycle should be notched for half its thickness and in
the notch a roller is fixed of about one inch in diameter. The notch should be
sufficiently long to allow the roller to rotate over the rail by which it is guided on
the forward half of the rotation of the lever. The roller should be sufficiently
thick to be able to rotate in its true plane, and it should have a projecting rim on
its inner edge to enable it to grasp the rail when on it.
At one end of the lever the axel which fixes the roller is prolonged outwards
and forms the axel that carries the pedal.
The sleeve should form in its section three sides of a rectangle .the other side
being formed by a flat piece to which it should be joined by screws, and should
allow the lever to slide with a minimum of friction, for which purpose a groove is
un on the inside on either side of the lever stopping short of the ends, in which
row of, steel balls is encased. The ends of the sleeve should be rounded off.
The rails should be in pairs screwed on brackets. The pair of rails is composed
of a lower one over which the roller should rotate and a parallel one above it and

page_text: around it at a sufficient distance to allow the roller to run between them. The
purpose of the upper rail is to ensure that the roller and the lever rotate in their
true planes, by supporting the rim of the roller on the side to which it tends to
incline. This rail is only required along the upper part as after the lever reaches
the horizontal it will no longer fulfil its purpose.
The two pairs of rails should be fixed together by cross pieces across the frame
of the cycle, and in front of the cogwheel. On the side of the cogwheel the pair
of rails must be fitted in between it and the lever, and I think this can be done
inside the space of an inch between the two.
I believe it will be unnecessary for the purpose of this Patent to enter into the
subject as to the means by which the rails should be fixed on the frame of a
velocipede.
I believe that if all the foregoing parts be suitably made and fixed, the following
result will be obtained viz.: that whilst one end of the lever carrying a pedal well
rotating, reach the rails and be at three inches from the centre of rotation, when
it gets at the opposite point it will be at seven inches, and I think that by a small
alteration in the measures given a greater difference could be obtained compatible
with facility of rotation.
The foregoing pieces are represented in Sheet No. 1 of the accompanying
drawings, and in Sheet No. 2 is represented the rotation of one roller over
a rail.
Sheet No. 1. C is on the crank at the centre of rotation. The crank is
represented in its position at three eights of a right angle from the vertical at C,
when the lower roller is leaving the rail and the upper one nearing it. In this
position the crank is supported on the sleeve by the pin f, near which a line shows
where the crank is notched at each end. is placed against the rim of a roller,
and g shows the outer rail supporting the rim, which may be necessary if much
pressure is made by the foot at the lower segment of rotation. e shows the pins
on which the rollers rotate, and one of which forms the pin for a pedal.
Sheet No. 2 shows the positions of a roller during its rotation over a rail. The
lines a show the middle plane of the crank passing through the centres C and e, at
successive points of rotation. This sheet shows the successive positions of the
points d in relation to the points h and i. d being the points of contact between
the rail and the circumference of a roller, the points where the middle plane of
the crank intersects the rail, and i the radii at 30° from the lines a. Between
these points the effect of contact between the rail and the roller is to lengthen the
crank as it sweeps along the rail.
The curve bb is obtained as follows: a line b c represents the vertical at the
centre C, and Ch a horizontal at the same point, and the two right angles are then
bisected, and each resulting angle again bisected till the lines a are obtained which
divide each right angle into eight parts.
The segment 60 of the rail is an arc of a circle having in the diagram a radius
of 2 inches. From 0 the radii increase as follows: a' is 28 in., a³, 24 in., a', 3 in.,
a, 3 in., a, 38 in., a', 4 in., as, 48 in., a, 4 in., a¹0, 5 in., a¹¹, 5 in., a", 6 in.
The increments are within the maximum increment possible.
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 :
That by combining the action of the pieces described, a lengthening and a
shortening of the pedal crank is obtained which while giving sufficient leverage
for propulsion shortens the backwards and upwards sweep of the pedal.
Dated this 28th day of March 1896.
EDWARD MATTEI, M.R.C.S...