Improvements in and relating to Bicycle Cranks.
Year: 1897

page_text: Date of Application, 30th Mar, 1897-Accepted, 29th May, 1897
COMPLETE SPECIFICATION.
Improvements in and relating to Bicycle Cranks.
I, ABRAHAM LINCOLN ADAMS, a citizen of the United States of America,
residing at Golden Hill Hotel, Harrison Street, in the City of Bridgeport, County
of Fairfield and State of Connecticut, one of the United States of America,
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 :-
My invention relates to certain improvements in bicycles, but more particularly
has reference to crank propulsion, the object being to so attach the pedal to the
propelling crank that positive means, independent of the pedal, for adjusting said
pedal may be operated by the rider to effect the automatic lengthening or shortening
of the crank leverage.
My improvement has nothing whatever to do with any construction wherein .
swinging bar is pivoted to the crank while the pedal is carried at the end of the
bar, the latter being swung inwardly and outwardly against abutments in the crank
to shorten or lengthen the latter; but my improvement contemplates so locking the
pedal in its adjustments that it cannot be released until the rider operates an
independent trip which controls the locking mechanism.
In the accompanying drawings which form a part of this application-
Figures 1 and 2 are sectional elevations showing a bicycle crank equipped with
my improvement, the position of the parts in Figure 1 being such as to increase the
leverage of the crank, while the position of the corresponding parts in Figure 2 is.
such as to decrease such leverage;
Figure 3, a section at the line -x of Figure 1;
Figure 4 a section at the line y-y of Figure 1;
Figures 5 and 6 are similar to Figures 1 and 2, but show modifications of my
improvement in which the crank pin and auxiliary crank are integral, while the crank
pin is capable of revolving within the crank, and means operated by the crank pin
and engaging with notches in the crank is employed to lock the crank pin in its
adjustments.
Figures 7, 8 and 10 are also sectional elevations showing modified forms of my
improvement, and
Figures 9 and 11 are sections respectively at the lines x-x of Figure 7,
and y-y of Figure 10.
Similar numbers of reference denote like parts in the several figures of the
drawing.
The broad principle which underlies my invention resides in the idea of an
auxiliary crank which is carried by the crank pin of the usual bicycle crank, the
pedal being carried by the auxiliary crank and so journaled in connection there-
with that its axis of revolution is eccentric to the crank pin while, in all instances,
a device accessible to the foot of the rider must be employed for unlocking the
auxiliary crank and for permitting. the same to be moved independent of the main
crank to positions which in reality effect the lengthening or shortening of the crank
leverage, as the case may be ;. but it is absolutely necessary that the locking of the
auxiliary crank in its adjustments should be automatic, and that the devices for

page_text: sing the locking mechanism should operate positively and entirely independent
of the pedal.
It will be clear that the adjustments of the auxiliary crank and the locking of the
same may be effected in any one of several ways, as follows:—
First; The crank pin may be stationary and the auxiliary crank mounted thereon
after the manner of a sleeve, so as to be capable of an independent revolution, in
which case a locking device would be carried by the auxiliary crank and would engage
with the crank pin, or vice versa, such device would be carried by the crank pin, and
would engage with the auxiliary crank.
Second; The crank pin and auxiliary crank may be made integral, and said
pin journaled within the bicycle crank so as to be capable of revolution, in which
case a locking device carried by said pin or auxiliary crank would engage with
the bicycle crank, or vice versa, such locking device would be carried by the
crank and would engage with said pin or auxiliary crank to lock said pin in its
adjustments.
Third: The auxiliary crank might be made circular and journaled within
suitable bearings in the bicycle crank, while the crank pin would be rigidly
secured to the auxiliary crank eccentric thereof, and the pedal would be journaled
on said pin, in which case a locking device carried by said auxiliary crank or pin
would engage with the bicycle crank, or vice versa, said locking device carried by
the bicycle crank would engage with said auxiliary crank or pin, to effect the
locking of such auxiliary crank in its adjustments.
The first two of these three constructions are included in Figures 1 to 9 inclusive,
while the third construction is shown in Figures 10 and 11.
In order that those skilled in the art to which my invention appertains may more
fully understand the same, I will now describe it in detail, and will refer to the
accompanying drawings which I have above described.
Referring to Figures 1 to 4 inclusive, 1 is the usual bicycle crank, 2 the crank
pin secured thereto in the usual manner by nut 3, and 4 is an auxiliary crank
having a hub which latter fits loosely around the crank pin so as to be
capable of rotation. This hub is kept in position by means of a washer 6 and nut 7,
the latter engaging the inner end of the crank pin and being forced firmly against
the washer.
8 is the crank spindle for the pedal secured to the crank 4 by means of nut 9,
and around this spindle is journaled the pedal 10 in the usual manner.
14 are
Pivoted between ears 11 projecting from the hub 5 is a latch 12, and 13 is a spring
which is made of wire and is of a circular shape and embraces the hub 5, one
extremity of this spring being connected with the inner end of said latch.
notches in the crank pin 2, and the function of the spring 13 is to cause the latch 12
to normally engage with one of these notches, whereby the auxiliary crank and the
crank pin 2 will be locked together.
15 is a lever pivoted at 16 to the auxiliary crank and resting upon the tail or outer
end of the latch 12, whereby, when said lever is depressed, the nose or inner end of
said latch will be raised out of engagement with the pin 2, thus permitting the
auxiliary crank to have an independent rotation around said pin, for the purpose
which I will now explain.
This lever is within convenient reach of the foot of the rider, so that if the
latter has been riding with the short crank leverage as shown in Figure 2, and
desires a greater propelling leverage, he merely slides his foot along the pedal,
and, when the latch is brought within reach by the revolution of the crank 1,
simply depresses the lever 15 with his foot, and immediately releases said lever.
The moment the lever is depressed the auxiliary crank commences to turn around
the pin 2, and when the latch comes opposite to the notch diametrically opposed to
that with which it had previous engagement, said latch will be forced into said notch
by the spring 13, thereby again locking the auxiliary crank and the pin rigidly
together, and effecting a lower normal adjustment of the pedal whereby the propelling
leverage is increased.

page_text: It will thus be seen that the crank propelling leverage may be lengthened or
shortened automatically and at the will of the rider, and without any necessity on
the part of the latter for dismounting or for using any tools.
By lengthening the crank great power is obtained, and this is advantageous for
the purpose of climbing hills, or when it becomes necessary to ride against head
winds or upon bad roads; by shortening the leverage a rider obtains a steadier,
quicker and easier motion for traveling on a level road, and experiences less
fatigue, since it is entirely unnecessary, in traveling on an ordinary good road, that
a large sweep and the consequent increased action of the limbs of the rider should
be had.
By alternately changing the leverage of the crank the rider is rested, and
moreover this leverage can instantly be adapted for easy or hard travel, as the
case may be.
Of course it will be obvious that the notches in the crank pin may be placed
around the same on the quarters, thus giving adjustments for three positions of
the pedal, namely, two at the extreme limits of the long or short leverage, and a.
third between these limits, and I therefore do not wish to be confined to the two
adjustments shown.
Referring to the construction shown at Figures 5 and 6, the crank pin and the
auxiliary crank are made in a single piece 17, the inner or crank pin end of which
is journaled within the crank 2 so as to be capable of turning therein.
A hub 17*
is formed on the outside of the main crank and around the opening in the latter
through which the crank pin extends, while pivoted within the crank pin outside of
the main crank is a latch 18 whose free extremity is normally projected within one
of the diametrically opposite notches 19 in the hub 17" by means of the spring 20
which latter is pivoted within the crank pin and bears upwardly against the latch.
21 is a lever which is pivoted to the crank pin in precisely the same manner as
the lever 15 is pivoted (see Figure 3) which lever rests upon the latch 18, whereby
when said lever is depressed, said latch will be thrown out of engagement with the
noteh 19, thereby permitting the crank pin to turn within the main crank until said
latch automatically is projected by the spring 20 into the diametrically opposite
notch 19.
It will be observed that this locking mechanism above described is substantially
the same as that illustrated in Figures 1 to 4 inclusive, and it will therefore be clear
that the main crank and the piece 17 will be normally locked together.
The position of the parts in Figure 5 shows the pedal in its lowest normal position,
and the crank leverage is therefore at its longest adjustment.
When the lever 21 is depressed by the foot of the rider, the latch 18 will be
thrown out of engagement with the main crank, thereby permitting the piece 17 to
turn independently within said crank until the latch has been thrown into the
diametrically opposite notch 19; the parts will then be in the position shown at
Figure 6, where the pedal is in its highest normal plane and the crank leverage is
therefore at its shortest adjustment.
It will thus be clearly understood that it is immaterial as to what parts
carry the locking devices the gist of my invention in this respect resting in
the broad idea of automatically locking the pedal in its two adjustments by means
controlled independent of the pedal itself, so that it is impossible for the rider
in pedaling or back pedaling to accidentally disturb or alter the adjustment of the
pedal.
I have heretofore described in this application the pedal journaled in the
ordinary mauner around a crank spindle which lattor is secured to the auxiliary
crank eccentric of the axis of the crank pin, but I do not wish to be limited to any
special manner of attaching the pedal since it is merely necessary that the latter
should have its axis of rotation eccentric to the axis of the crank pin, and I will now
describe the modification shown in Figures 7, 8 and 9, in which the auxiliary crank
is in the form of an ordinary eccentric while the pedal is journaled directly upon
the eccentric without the use of any crank spindle.

page_text: The crank pin is provided with a long extension 22 at its inner end, and around
this extension the extended hub 23 is journaled so as to be capable of revolving,
and the auxiliary crank is formed into an ordinary eccentric 24, which latter may
be integral with the hub or it may be secured thereto, as in the present instance,
by screws 25 driven into said eccentric through flanges 26 extending from
the hub.
Around this eccentric is journaled the pedal 27 in any
suitable manner,
although in the present instance I have employed ball bearings 28 with the usual
keeper ring 29.
From the foregoing it will be clear that the axis of revolution of the pedal is
not in the same horizontal plane with the axis of the crank pin.
In Figure 9 the axis of the pedal is lower than the axis of the crank pin
extension 22, and therefore the leverage of propulsion is increased, while in
Figure 8 the axis of the pedal is above the axis of said extension, and the
leverage of propulsion is therefore shortened, this of course being clearly under-
stood when it is borne in mind that when the long radius of the eccentric extends
downwardly the pedal is at its lowest position and vice versa, when said radius
extends upwardly the pedal is at its highest position.
30 is a yoke which surrounds the inner end of the hub and is capable of a free
vertical sliding movement, and carried by this yoke and secured thereto by
serew 32 is a pin 33. The hub is pierced at 34 to provide an opening through
which the pin may extend, while the crank pin is provided with notches 35 into
which said pin may also extend when said notches come into registration with the
opening 34. 36 is a spring which is secured to the inside of the eccentric and
extends immediately beneath the yoke 30, the function of which spring is to
normally exert a pressure upon the yoke to drive the pin 33 toward the crank pin.
Let us suppose that the parts are in the position shown at Figure 7, and should
the rider desire a shorter crank leverage he merely presses with his foot upon the
yoke 30, thereby throwing the pin out of the notch 35 in the crank pin and
permitting the hub to revolve around the crank pin. The foot of the rider is
removed immediately after depressing the yoke, and when the hub which carries
the eccentric has revolved around so that the pin 33 will be opposite the other
notch 35 in the crank pin, said pin 33 will engage with the last named notch aud
will thereby lock the hub and crank pin together in the position shown at Figure 8
wherein the shortest leverage of propulsion is illustrated.
Of course there may be more than two of these notches 35, so that a medial
adjustment of the pedal may be obtained and I do not wish to be limited in this
respect.
There is in reality no difference, mechanically speaking, between the construction
shown at Figures 1 and 2 and Figures 7 and 8, since if the crank spindle 8 were
made commensurate in size with the auxiliary crank 4, the result would be the
eccentric shown in Figures 7 and 8, the condition obtained in both instances being
that the axis of the pedal is eccentric to the axis of the crank pin.
In Figure 10 1 have shown the crank pin enlarged into the form of a disk 37
which latter is journaled within the main crank in any suitable manner, as for
instance by ball bearings 38 secured by means of the usual keeper ring 39, and
the crank spindle 8 for the pedal is shown projecting from said disk but from a
point eccentric to the axis of rotation of said disk so that it will be clear that
when the disk is revolved the crank spindle will be elevated or lowered as the case
may be.
The main crank is provided with a hub 40 on its outer face, and around the
opening within which the disk is journaled, and this hub is provided with
diametrically opposite notches 41. 42 is a yoke around the crank spindle at or
about the point where the latter joins onto the disk 37, which yoke is capable of a
vertical sliding movement and is kept in normally elevated position by means of
a spring 43 which is secured to the disk and bears against the under side of the
yoke. A stud 44 extends from this yoke toward the main crank and is normally

page_text: projected by means of the spring within one of the notches 41, so that it will be
clearly understood that the main crank and the disk will be normally locked:
together.
The position of the parts in Figure 10 shows the pedal in its highest normal
position and the crank leverage is therefore at its shortest adjustment.
The yoke is within easy access of the foot of the rider, and when said yoke is:
depressed the stud 44 will be thrown out of engagement with the notched hub
thereby permitting the disk 37 to turn independently within the main crank until
the stud has been thrown into the diametrically opposite notch 41 and the parts:
will then be in the position where the pedal is in its lowest normal plane and the
crank leverage is therefore at its longest adjustment.
I have shown the crank pin made integral with the disk but of course it will
be obvious that said pin may be made separate from the disk and rigidly secured
thereto by a nut, and I therefore do not wish to be limited in this respect.
It will be clear that the construction shown in Figure 10 is substantially the
same as that shown in Figures 5 and 6, the only difference being that the crank pin
bearings in the main crank shown in Figures 5 and 6 is small, while in Figure 10
this bearing is enlarged.
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 :-
1. In a bicycle, the combination of the main crank, the crank pin, the auxiliary
crank carried by said pin and capable of being swung around its axis, the pedal'
carried by the auxiliary crank, and positive means independent of the auxiliary
crank or the parts carried thereby for locking and unlocking said auxiliary
crank and for permitting it to swing in its axial adjustments, substantially as set.
forth.
2. In a bicycle, the combination of the crank and the crank pin, the auxiliary
crank carried by said pin and capable of being swung around its axis, the pedal
spindle secured to said crank eccentric to the axis of said pin, the pedal suitably
journaled around said spindle, and means controlled by the rider and independent
of the pedal for automatically and positively locking said auxiliary crank in its.
axial adjustments, whereby the normal plane of the pedal is elevated or lowered.
and the crank propelling leverage shortened or lengthened accordingly, substan-
tially as set forth.
3. The combination of the crank, the crank pin secured thereto, the auxiliary
crank carried by the crank pin and capable of rotation around its axis, the pedal
carried by the auxiliary crank, and means carried by the rotary auxiliary crank.
and co-operating with the bicycle crank or a part rigid therewith and operated and
controlled by the rider independent of the pedal for effecting the rotation of said.
auxiliary crank and the automatic locking of the latter in the different horizontal.
planes, substantially as set forth.
4. The combination of the bicycle crank, the crank pin rigid therewith and
having around the circumference of its inner portion a plurality of notches, the
auxiliary crank having a hub journaled around the inner end of said pin, the,
pedal crank spindle secured to said auxiliary crank, the pedal journaled around
said spindle, the latch pivoted to said hub, the spring whereby said latch is.
normally engaged with one of the notches in the crank pin, and the lever within
reach of the foot of the rider and pivoted to the auxiliary crank, substantially as.
set forth.
5. The combination of the main crank, the crank pin journaled therein so as to
revolve, the pedal carried by the crank pin and having an axis of revolution
eccentric to the axis of said pin, the notched hub extending from the outer face of
the main crank around the crank pin, the spring actuated latch pivoted within the
crank pin and capable of normally engaging with said notched hub whereby the
main crank and crank pin are locked together, and the lever pivoted to the crank.

page_text: pin and resting upon the latch and accessible to the foot of the rider, substantially
as set forth.
6. The combination of the main crank, the crank pin rigid therewith, the hub
journaled around said pin and capable of revolving, the eccentric carried by said
hub and constituting the auxiliary crank the pedal journaled around said eccentric,
the yoke surrounding the inner end of the hub and capable of a free vertical
sliding movement, the pin carried by said yoke and capable of projecting through
an opening pierced in the hub, the notches in the crank pin with which said yoke
pin may engage when said notches come into registration with the opening in
the hub, and the spring which exerts a pressure beneath the yoke whereby the
pin carried thereby is normally driven toward the crank pin, substantially as set
forth.
7. In a bicycle, the combination of the crank the disk journaled within the crank
and having projecting therefrom a crank spindle, the pedal journaled around said
spindle, and means for locking and unlocking said disk in its axial adjustments,
substantially as set forth.
8. In a bicycle, the combination of the main crank, the disk journaled within
said crank and having projecting therefrom a crank spindle, the pedal journaled
around said spindle, and means carried by said disk and engaging with the main
crank and operated by the rider for permitting the rotation of said disk and for
automatically locking the latter when said spindle is in different horizontal planes,
substantially as set forth.
9. The combination of the main crank having a plurality of notches, the disk
journaled therein and having extending therefrom the crank spindle, the pedal
journaled around said spindle, and the spring actuated locking yoke carried by
said disk and having a stud adapted to engage with said notches, substantially as
set forth.
Dated this 20th day of March 1907
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.