Improvements in Crank Driving Mechanism for Cycles and other Machinery.
Year: 1897

page_text: Date of Application, 2nd Sept., 1897
Complete Specification Left, 2nd June, 1898-Accepted, 2nd July, 1898
PROVISIONAL SPECIFICATION.
Improvements in Crank Driving Mechanism for Cycles and other
Machinery.
I, DAVID CUTLER, of Cox Street, Livery Street, in the City of Birmingham,
Manufacturer, do hereby declare the nature of this invention to be as follows:-
This invention relates to crank driving mechanism for cycles and other
machinery, and has for its object, to obtain an increase of power by the employ-
ment of expanding or extending cranks.
In carrying out my invention in connection with crank-operated driving gear
or mechanism for cycles (the two sides of which gear being alike, only one side
will be described) I make fast upon the end of the driving spindle, a chain wheel,
between the inside of which and the framing of the machine, I arrange a fixed
excentric or cam plate disposed considerably out of the centre of the system and
being surrounded by a strap, ring, plate or equivalent, which is connected in
common by a pin to a pair of short links or knee-jointed levers whose outer ends
are jointedly connected to the inner ends of a pair of primary links, connected to
the principal spindle, whilst their other ends are jointed to a second pair of links
or levers, forming a system of compound levers somewhat alike unto a lazy tong,
whose ends are connected and jointed together by the inner end of the pedal pin.
One of the members of the pair of inner links is made fast by a pin to the chain
wheel, so that only its twin link opens and closes whilst the said fast link moves
relatively with the chain wheel.
Thus the outer termination of the lazy-tong-like expanding crank carries the
pedal, whilst the members at the other end are connected by a pair of small twin
links to the strap or ring surrounding the excentric, so that as the crank is driven
round by foot-pressure applied to the pedal, the primary links, when commencing
their downward movement, come together and extend the length of the crank
in the direction of a straight line and after the descending movement is complete,
then on the commencement of the ascending part of the rotation, they commence
to close, and the distance between the pedal and the axis is materially decreased.
By making the opening and closing links to form the crank and governing
them by a supplementary pair of links as described, great length of throw of the
aforesaid compound crank is obtained during the descending movement, and at
the point where no driving power is required to be exerted then the said crank
may collapse so as to bring the pedal to such a distance from the axle or spindle
as to come nearly within the circumference of the chain wheel, whilst owing to
the arrangement of compound links or levers the throw of the cam is considerably
multiplied in the expanding movement of the crank.
The cam or excentric is made fast to the framing of a machine and the whole
system revolves around it. The whole of the joints and contacting surfaces may
be provided with ball bearings to reduce friction.

page_text: The application of my invention to the driving mechanism of other machinery
differs in no essential respect from its application to cycles as herein described.
Dated this 1st day of September 1897.
DAVID CUTLER,
By Henry Skerrett,
Agent for Applicant.
Improvements in Crank Driving Mechanism for Cycles and other
Machinery..
I, DAVID CUTLER, of Cox Street, Livery Street, in the City of Birmingham,
Manufacturer, 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 crank driving mechanism for cycles and other machinery,
and has for its object, to obtain an increase of power by the employment of expan:l-
ing or extending cranks.
Figure 1 of the accompanying drawings represents a side elevation of a safety
bicycle, fitted with expanding-crank driving mechanism constructed according
to my invention.
Figure 2 represents upon an enlarged scale, the said driving mechanism and
expanding crank gear separately.
Figure 3 is a plan of Figure 2, with the chain wheel on the right hand side
shown in section and with the upper pair of crank arms on the left hand side being
broken away across the dotted lines A and B Figure 2.
Figure 4 is another elevation of the said mechanism, but with the parts of the
compound crank on the one side shewn only in dotted lines, in order to better
exhibit the arrangement of the excentric and strap by which the expansion and
conitaction of the crank is governed. In this view the left hand crank is expanded
to its greatest length, whilst the right hand crank is contracted.
Figure 5 is a like view as Figure 4, but with the left hand cranks contracted
and the right hand one expanded.
The same letters of reference indicate corresponding parts in the several figures
of the drawings.
According to this invention, I mount upon each end a¹, of the bottom bracket
or crank axle bearing a, of the machine, a fixed excentric or cam plate, that on
right hand side being marked b, and that on the other side . Each plate is dis-
posed considerably out of the centre of the system and is surrounded by a strap
or loosely-fitted ring c, which is capable of making a rotatory movement around
the said plate, ball or other bearings being preferably introduced between the
opposed peripheries of the said parts in order to minimise friction. Each said
strap carries a plain or rollered pin or stud, that on the left hand d, passing through
the slot e', of a driving crank plate e, which is disposed across the outer face of the
excentric and is keyed at its inner end to, and is adapted to turn with and (as
hereinafter described) communicate driving motion to the axle or spindle a², of the
bracket a, whilst the pin 2, of the strap on the right hand side passes into a slot g¹.
in a second driving plate g, which is either also keyed directly to the spindle a³, or
is made an attachment to the chain wheel h, secured to the said spindle, or the said
stud, may take into a slot made in one of the arms or other suitable parts of the
said chain wheel.
Jointedly connected to each of these studs d, d, (the arrangement being the

page_text: same on either side of the machine) is a pair of short articulated links or knee-
jointed levers i, i¹, whose inner ends 22, 23, meet and overlap one another at the
point of their connection with the stud, whilst their outer ends 2, ³, are respec-
tively jointed to near the inner ends of the pair of primary links 1, 2, pivoted to
the spindle, or otherwise, constituting the inward members of the compound
crank j, with their outer ends being jointed in turn to the adjacent ends of the
other pair of link members 3, j, which are jointedly connected to one another at their
extreme outer ends and carry the pedal pin k, upon which the pedal 4, is carried, so
that the said link members together form a crank comprised of a series of links, so
arranged and articulated that they comprehend a diamond figure, and which may
be elongated or extended and collapsed, somewhat alike unto lazy tongs, with the
extending and collapsing movement governed and effected by the rotation of the
strap around the fixed or stationary excentric imparting a longitudinal move-
ment to its pin within the slot of the driving plate, whereby the knee-jointed
links are alternately straightened out or brought nearly into line with one another,
and closed together and which thereby acts upon the inner links of the expanding
crank and causes the members thereof to extend at the point when the greatest
leverage is required and then to collapse.
Thus, when the crank is driven round by foot pressure exercised upon the pedal
(assuming the same to be in the collapsed position represented on the nearmost side
of Figure 2) the excentric and its stud are carried round the fixed strap, and as
the distance between the said pin and the spindle is gradually increased, so the
knee-jointed links are drawn together and they in turn, draw inwards the inner
links of the crank which is thus, as its rotation proceeds, gradually extended and
the distance between the pedal of its outer end and the spindle is increased, with
a corresponding increase in leverage, until the pin on the strap reaches the limit
of its movement, when the crank is then extended to its greatest length, that on
the other side of the machine being at this time fully collapsed, it being understood
that during the time that the crank on the one side is extending that on the other
side is in the act of collapsing.
The driving power exerted through this system of expanding cranks is transmitted
through the levers and links to the pins on the governing excentric straps, which
pins move to and fro within the slots of, and transmit driving force to, the crank
plates or their equivalent keyed onto the spindle.
then
By making the system of opening and closing links to form the crank and
governing them by a supplementary pair of links as described, great length of
throw of the aforesaid compound crank is obtained during the descending move-
ment, whilst at the point where no driving power is required to be exerted,
the said crank collapses so as to bring the pedal to such a distance from the axle
or spindle as may come nearly within the circumference of the chain wheel, whilst
owing to the employment of the described arrangement of compound links or
levers the throw of the cam is considerably multiplied in the expanding move-
ment of the crank.
be
The cam or excentric is made fast to the framing of a machine and the whole
system revolves around it. The whole of the joints and contacting surfaces may
provided with ball bearings, to reduce friction.
The application of my invention to the driving mechanism of other machinery
differs in no essential respect from its application to cycles as herein described.
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-
First: An expanding crank-driving mechanism, comprising a system of articu-
lated or compound levers, provided with a pedal and being opened out and closed
by a pair of links arranged in conjunction therewith and controlled by a stud or
pin carried by an excentric strap or equivalent which is caused to move around a
fast excentric plate, whilst driving motion is transmitted to the spindle by the

page_text: pin on the said strap acting upon a slotted arm or plate or equivalent, made fast
to the said spindle, substantially as described and set forth.
Secondly: An expanding crank for driving mechanism, consisting of a series
of levers articulated together so as to form a lazy tong and controlled or opened
and closed by links or equivalent, in connection with cams, excentrics, cranks or
the like, having driving connection with the axle or spindle to be driven, sub-
stantially as described and set forth.
I
1
T
1000
DAVID CUTLER,
By Henry Skerrett,
24, Temple Row, Birmingham, Agent for Applicant.
-
DAVID CUTLER,
By Henry Skerrett,
, Temple Row, Birmingham, Agent for Applicant.
4