Improvements in Variable Throw Cranks.
Year: 1896

page_text: Date of Application, 22nd Dec., 1896
Complete Specification Left, 23rd Sept., 1897-Accepted, 23rd Oct., 1897
PROVISIONAL SPECIFICATION.
Improvements in Variable Throw Cranks.
We, ARTHUR GEORGE MUMFORD of the Culver Street Iron Works, Colchester,
in the County of Essex, Engineer, and ALFRED ANTHONY, of 19, Beaconsfield
Avenue, in the town and County aforesaid, Draughtsman, do hereby declare the
nature of this invention to be as follows:-
This invention relates to an improved construction of that type of variable
throw crank consisting essentially of a crank arm and of a swinging link pivotted
thereto the movement of which is controlled by a spring and it consists in making
the crank arm tubular or hollow to contain the spring controlling the movement
of the swinging link carrying the pedal, in connecting the swinging link with the
compression spring in such a manner that no back lash in the said link can arise
through wear, and in various improvements in details hereinafter more particularly
specified.
In carrying this invention into practice the crank is made of a length of tube
having at one end a snug by which it is attached to the axle by a key or cottar pin
in the usual manner. On the other end of the tubular crank is fixed a socket
carrying a web on to which is pivotted-preferably by a ball bearing of large
diameter the swinging link for carrying the pedal.
In the tubular crank slides a plunger or its equivalent which acts on a spring
contained therein, the end of the crank arm carrying the snug by which it is
attached to the axle being closed by a suitable screwed cap, in addition to which
it has a threaded plug for adjusting the strength of the spring.
On the periphery of the disc of the swinging link is a curved projection with
which a stud or its equivalent carried by a rod engages, the other end of the said
rod engaging with the plunger in the tubular crank. Acting on the front end
of the said rod or on the stud carried by it is a spring carried by the web on the
end of the crank arm which is so shaped and arranged that it acts not only to keep
the said stud up against the curved projection on the disc of the swinging link
but also as a buffer spring on the return of the swinging link to its normal position.
As an alternative construction the forward end of the rod connecting the
swinging link with its controlling spring may take the form of a rack adapted to
engage with teeth formed in or ou the periphery of the disc of the swinging link.
The web on the end of the crank arm is so shaped that it entirely encloses the
connecting rod and its attachments, and the parts of the case so formed which fit
over the disc of the swinging link are provided with wipers to prevent the lubricant
used from flowing or spreading over the swinging link.
Dated this 22nd day of December 1896.
ROBERT E PHILLIPS, Assoc. M. Inst. C.E., M.I. Mech. E.
Consulting Engineer and Patent Agent,
70, Chancery Lane, London, W.C., Agent for the Applicants

page_text: Improvements in Variable Throw Cranks.
"
We, ARTHUR GEORGE MUMFORD of the Culver Street Iron Works, Colchester,
in the County of Essex, Engineer, and ALFRED ANTHONY of 19 Beaconsfield
Avenue in the town and County aforesaid, Draughtsman, do hereby declare the
nature of this invention and in what manner the same is to be performed to he
particularly described and ascertained in and by the following statement:-
This invention relates to an improved construction of that type of variable
throw crank consisting essentially of a crank arm and of a swinging link pivotted
thereto the movement of which is controlled by a spring and it consists in making
the crank arm tubular or hollow to contain the spring controlling the movement
of the swinging link carrying the pedal, in connecting the swinging link with the
compression spring in such a manner that no-back lash in the said link can arise
through wear, and in various improvements in details hereinafter more particularly
specified.
In the accompanying drawing which illustrates this invention:-
Figures 1 and 2 are views in side elevation the former partly in section.
Figure 3 is a view in plan partly in section.
Figure 4 is a view in end elevation and
Figure 5 is a' view in transverse section on line x Figure 1 with the swinging
link fully extended...
Throughout the views similar parts are marked with like letters of reference.
The arm A of the crank is made of a length of tube having at one end a snug A¹
by which it is attached to the axle by a key or cottar pin a in the usual manner.
On the 'other end of the tubular arm A
A is fixed a socket A2 carrying a web al on
to which is pivotted preferably by a ball bearing of large diameter-the
swinging link B for carrying the pedal, the said link being provided with the usual
split socket adapted to receive the pin carrying the pedal.
In the outer end of the tubular arm A of the crank slides a plunger C or its
equivalent which acts on a spring D contained therein, the strength of the spring
being capable of being varied by means of a plug E screwed into the end of the
tubular arm carrying the snug A which is threaded to receive both it and a closing
cap F as shown:
On the periphery of the disc b' of the swinging link B is a projection 6 carrying
à stud G which engages with the curved end of a rod H, the other end of which
engages with the plunger C in the tubular arm of the crank. Acting on the
stud G in' engagement with the end of the rod H is a spring J carried by the
web a¹ on the end of the arm A of the crank. This spring is so arranged that it
acts not only to keep the stud G up against the curved end of the rod H, but also
as a buffer on the return of the swinging link B to its 'normal position, after
extension:
As an alternative construction the forward end of the rod H connecting the
swinging link B with its controlling spring D may take the form of a rack
adapted to engage with teeth formed in or on the periphery of the disc b¹ of the
swinging link.
.J
The web a¹ on the end of the tubular arm A of the crank is provided with
suitable flanges forming a box and it has a covering plate a3 so that the rod H
and its attachments are completely enclosed and the parts of the case so formed,
which! fit over the disc of the swinging-link, are preferably provided with wipers
to prevent the lubricant used from flowing or spreading over the swinging link.

page_text: Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is:
1. A variable throw crank consisting essentially of a tubular arm such as A
having a snug such as A¹ at one end and a web such as a' at the other end, of
a swinging link such as B pivotted to the web a' of the crank arm A. and adapted
to carry the pin of the pedal, of a spring such as D) located in the tubular arm A.
and adapted to control the movement of the link B, of a rod such as H acting
between a projection 63 on the disc of the swinging link B and a plunger C
sliding in the tubular arm A and acting on the spring D contained therein, and
of a spring such as J carried by the disc a¹ of the tubular arm A. and acting on
the swinging link B through its projection 62, as and for the purpose set forth.
Dated this 23rd day of September 1897
ROBERT E. PHILLIPS, Assoc. M. Inst. C.E., M.I. Mech. E.
Consulting Engineer and Patent Agent,
70, Chancery Lane, London, W.C., Agent for the Applicants