IMPROVEMENTS IN CRANKS FOR VELOCIPEDES
Year: 1886

page_text: I JOHN HARRISON of 39 Hyde Street, Winchester, in the county of Hampshire
Engineer and Millwright do hereby declare the nature of my said invention for
"IMPROVEMENTS IN CRANKS FOR VELOCIPEDES," to be as follows:-
The object of my invention is the construction of a crank for velocipedes the
throw of which shall automatically increase during the downward stroke and
decrease during the upward stroke so that the rider has all the advantages of a
long throw crank, without any of the disadvantages attendant on the use thereof.
My crank is constructed as follows:-I take a flat plate forming a crank arın pro-
vided at one end with a bush by which it is keyed to the end of the crank shaft
in the usual manner. Near the end of this plate is pivotted a small lever which
I call a radius lever carrying at its free end a stud pin which engages with the end
of a radius arm provided at its free end with a slot to carry the pedal. This
radius arm is guided through suitable guides so that it is free to move longi-
tudinally with respect to the crank arm. The action of the radius arm is controlled
by the pin of the radius lever which engages with a slot in the crank arm struck
from the centre of the pivotting pin of the lever. When the crank arm is at its
shortest throw, the radius lever connecting the radius arm lies nearly at right angles
to the centre of the line of the crank arm and as the radius arm slides outwards the
lever gradually assumes a position incidental with the centre line of the crank arm.
A suitable spring is provided to force the radius lever backwards to its normal
position. The lever and arm constituting the lengthening mechanism of the crank
arm are covered in, in a suitable manner to exclude dust and dirt and protect the
working parts from possible injury. The action of the crank is as follows:-When
its pressure is applied to the crank arm on its downward stroke the length of it
is automatically altered in proportion to the pressure exerted, and as the crank
arın rises so its length is automatically shortened due to the spring operating the
radius lever in the manner herein before described.
It will be obvious that the details of the construction of my crank may be varied
without departing from the principle of my invention.
ROBT. ED. PHILLIPS, M.I.M.E.,
Consulting Engineer & Patent Agent,
Royal Courts Chambers,
70, 71, & 72, Chancery Lane, London, W.C.,
Agent for the Applicant.

page_text: I JOHN HARRISON of 39 Hyde Street Winchester, in the County of Hampshire,
Engineer & Millwright 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 object of my invention is the construction of a crank for velocipedes the
throw of which shall automatically increase during the downward stroke, and
decrease during the upward stroke, so that the rider has all the advantages of
a long throw crank, without any of the disadvantages attendant on the use
thereof. I construct my crank as follows:-I take a crank arm having at one
end a boss, provided with a hole to receive the end of the crank shaft on to which
it is keyed or otherwise fixed in the usual manner.
In the outer face of the crank arm which is made of a semicircular form, I form
a slot in which fits a radius arm provided at its outer end with a slot to receive
the end of the pedal pin. This radius arm is controlled by a spring either directly,
or indirectly through a radius lever pivotted on the crank arm, so that the radius
arm can only be extended against the power of the spring, which restores it to its
normal position at the end of each stroke. A suitable cover is provided to enclose
the radius arm in the slot in the crank arm, and protect it from dust and dirt, and
possible injury..
The action of the crank is as follows:-When pressure is applied to the crank
arm on its downward stroke, the length of it is automatically altered in proportion
to the pressure exerted, and as the crank arm rises, so its length is automatically
shortened, due to the spring operating on the radius arm in the manner hereinbefore
described.
In order that my invention may be fully understood I will particularly describe
it making reference to the accompanying drawing which illustrates the simplest
method of carrying my invention into practical effect.
Figs. 1 and 2 are a side and front elevation respectively of a left hand crank, in
its normal state; and Fig. 3 is a side elevation showing the same crank extended.
Throughout these views similar parts are marked with like letters of reference.
Referring to these figures, A designates the curved crank arm.
B the curved
radius arm fitting in the slot a formed in the crank arm. C the cover plate secured
by screws c, c, and the small bolt c which passes through both the crank arm and
the radius arm, which is slotted to allow of its movement. This small bolt acts as
a stop to limit the motion of the radius arm. D designates the spring which is of
the tape or ribbon type, and is fixed at its inner end to the stud d mounted in
the slot in the crank arm, and at its free end to a snug b at the inner end of the
radius arm B. The strength of the spring D may be varied by winding it up or
unwinding it, the square end of the stud d engaging in the square hole in the cover
plate C, locking it in any position.
It will be obvious that the details of my invention may be varied in many ways
without going beyond the scope of my invention.

page_text: Having now particularly described the nature of my said invention, and in what
manner the same is to be performed, I declare that what I claim is :—
First-
-An automatically variable throw crank, constructed, arranged, and
operating as herein before described and shown.
Second-In an automatically variable throw crank, the construction of the
crank in two parts, the relative positions of which are controlled by a spring,
as hereinbefore set forth.
Third: In a crank the throw of which is automatically variable due to the
pressure exerted through it, the combination of the curved crank arm A, the
curved radius arm B, and the spring D, all combined, arranged and operating,
as and for the purpose herein before set forth.