Improvements in Cranks, Especially a Tread-crank for Velocipedes, the Pedals of which Rotate Elliptically.
Year: 1888

page_text: Improvements in Cranks, Especially a Tread-crank for Velocipedes,
the Pedals of which Rotate Elliptically.
FRIEDRICH PAUL ALWIN VICTOR, Doctor of Philosophy, Engineer, Pfaffenstrasso
No. 8, Osnabruck, Germany do hereby declare the nature of this invention to be as
follows:-
My invention relates to cranks generally, and to tread cranks for Velocipedes
especially, bicycles as well as tricycles. Over and over again allusions have been
made as to the inadequateness of the common ciren'ating cranks of velocipedos now in
use, since their turning in a circle differs so much from the natural motion of the feet
when walking on the ground. Various attempts have been made to improve the rotary
movement of the pedals or treadles by employing double-armed levers of different
constructions especially in Bicycles. One arm of the levers bearing the pedal the
other being directly or indirectly hinged on the fork of the front wheel in Singer's safety
bicycle "Extraordinary" the motion of the pedals of those bicycles is rather more
inconvenient than that of common circular imoving pedals, since it does not at all
correspond to the movements of the feet habitual in walking. My invention consists
in the construction of cranks the pedals of which are turning in ellipses instead of
circles as is the case with common cranks now in general use. These ellipses being
variable as to their eccentricity as well as to the direction of their transverse axis they
enable the velocipedist to vary the rotation of the pedal, according to his liking by
causing its form to approach either a circle or a straight line as hereafter will be more
fully described and shown.
The principle of the new crank is based on a proposition or theorem known from
kinematics and running as follows. "If the geometrical locus of the instantaneous
centre of rotation of a uniformly moving plain "system" represents a circle described
by the said point with uniform velocity but in the opposite sense of rotation of the
systein itself, every point of the system runs along an ellipse the centre of which
coincides, with that of the said circle.
I fix on the bearing or driving axle a spur or cog wheel of a diameter suitable to
my purpose which is fixed to the frame of the tricycle and allows the bearing to

page_text: revolve through its centre, but cannot move itself. To the said bearing or driving
axle, which projects a sufficient distance from the spur wheel, I fix a crank (called
the maincrank) carrying at its other end another spur wheel of smaller diameter,
which is fixed to another crank (called the by-crank).
To this by-crank the pedal is fixed. An endless chain passes round the two spur
wheels, or I
may fix an intermediate spur to the main crank and dispense with the
chain.
->
If the main crank turns once round its axle the axis of the wheel and of the by-
crank is carried along and describes a circle round the axis of the main crank axle.
During a complete rotation of the main crank the wheel participating in this
rotation in the one direction and turning by impulse of the chain (or the intermediate
wheel) twice round its own axle in the opposite sense, compels the by-crank to
perform one real rotation contrary to that of the main crank.
In consequence all parts of the by-crank and especially the axle of the pedal move
elliptically round the driving axle.
There remains to be shown how this elliptical rotation may be varied as to the
eccentricity, or the form of the ellipse described by the pedal and to the direction of
its transverse axis.
Concerning the form of the ellipse a two-fold arrangement has been chosen to effect
its variation. For the first, a slit has been arranged in the arm of the by crank as
known from tread cranks now in use, the axle of the pedal being put through the slit
nearer to one or the other end of it and screwed to the crank and in combination with
the slit the axle has got a double curvature (shaped) so that the pedal may be disposed
either neurer to or more distant from the axle than the twice curbed and of the axle
screwed to the crank. Both of these means combined admit to place the pedal or
rather its axle on the crank at any desirable distance from the axle, this variability
being limited by the length of the slit and the amount of the inflection or bend of the
axle is much more considerable than that of the cranks now known and used with
circularly rotating pedals. As to the extreme positions of the pedals of the new crank
for velocipedes, care has been taken to rationally limit the above mentioned distance
of the pedal-axle from the by crank axle in order to prevent its becoming either
quite equal to zero or quite equal to the length of the main crank or middle distance
of the crank axles. The smaller that variable distance is arranged, the more circular
the form of the ellipse, making the pedals rotate in a manner more and more
resembling that of common circular cranks and the longer that distance between the
axles the more flat the ellipse, finally almost degenerating into a straight line of the
double length of the diametre of the circle described by the axle. Thus being able to
vary to ones liking the form of the ellipses of the pedals from circular ones to rectilinear
ones, the direction of the transverse axis of the ellipses admits of no change as long as the
wheel has not been loosened from the ring and fastened to it anew in another position
or the chain (or the intermediate wheel) has not been turned round on the wheel giving
in such a way an impulse to the wheel causing it to make a turn by which the by
crank changes its position relatively to the main Crank so as to turn the direction of
the transverse axis of the pedal ellipses. A full circle of holes for the screws is
arranged in the plate or disk of the wheel all of equal distances from each other. If
the position of the wheel is varied by transposing the screws from hole to hole, the
direction of the ellipses is turned in the same sense and to the degree of the turn of
the wheel.
The descriptions given above may be generally suitable to most cases in which tho
new elliptical crank will be adopted instead of common circular cranks, but of course
they are to be adapted to the particular construction and to the form of the frame of
the bicycle or tricycle to be provided with these cranks. No less than seventy-
two (=8x9) ellipses, different from each other as to their form and the direction of
the transverse axis will be at the option of the rider, who will soon find out the one
most convenient to him and he may either employ the same ellipses once for all, or
in particular cases may choose any other ellipse that he inay think more appropriate
to his special purpose. There can be no doubt, that for general use, flat horizontal

page_text: ellipses as most corresponding to, if not entirely identical with the motion of the feet
in walking will render the least fatigue to the rider.
Notwithstanding. other arrangements of the ellipses may be preferred in some
vertically arranged flat ellipses will enable the Velocipedlist. to reach an extraordinary
velocity, his physical strength being officaciously supported and inscreased by the
weight of his body; these ellipses therefore may be chosen for races.
Riders whe
are accustomed to common circularly rotating pedals may begin with practising
ellipses of a circle-like form aud by degrees change to more flat ones.
As to the bearings of the axles they may be either cylindrical, conical or ball-
bearings. Having described my invention and its operation in application to tread-
cranks for velocipedes, I have to add a few words with regard to other applications of
the new elliptical or straight line crank. Particular detailed descriptions of these
application in view will not appear to be necessary since they require less complicated
arrangements than the cranks for velocipedes described. It will be sufficient to show
the manner in which the new crank can be applied to engines or receivers of any
kind in order to supersede cross-head guides and other arrangements of like purpose.
If the by crank is provided with a simple pivot. instead of a pedal as repeatedly
mentioned before, and the distance of the pivot from the axle corresponds exactly
with the distance between the axles measured from axis to axis, the pivot moves in
ellipses degenerated into straight lines. This oscillating motion can be put to use by
connecting the piston rod of the cylinder of the machine directly to the pivot of the
by crank, no variability as to the position of the wheel or the chain (or intermediate
wheel) or to the position of the pivot itself being needed in this case. By this
arrangement all differences in the up and down stroke of the piston as now existing
are totally precluded, the uniformly variable motion of the Piston being exactly the
same in both directions.
טו
1
T
E. EATON & Co.,
Agents for Applicant.

page_text: Improvements in Cranks, Especially a Tread Crank for Velocipedes,
the Pedals of which Rotate Elliptically.
FRIEDRICH PAUL ALWIN VICTOR Osnabruck Prussia Germany Doctor of
Philosopher, Engineer, do hereby declare the nature of this invention and in what
manner the same is to be perforined, to be particularly described and "ascertained in
and by the following statement :-
My invention relates to cranks generally, and to tread-cranks for velocipedes
especially, bicycles as well as tricycles.
Over and over allusions have been made as to the inadequatenesses of the common
rotating cranks of velocipedes now in use, since their turning in a circle differs so
much from the natural motion of the feet when walking on the ground. Various
attempts have been made to improve the rotatory movement of the pedals or treadles
by employing double-armed levers of different constructions, especially in bicycles.
One arm of the levers bearing the pedal, the other being directly or indirectly hinged..
on the fork of the front wheel, as in Singers safety bicycle "Extraordinary," the
motion of the pedals of those bicycles is rather more inconvenient than that of
common circularly moving pedals, since it does not at all correspond to the move-
ments of the feet habitual in walking.
My invention consists in the construction of cranks, the pedals of which are
turning in ellipses instead of circles as is the case with common cranks now in general.
use. These ellipses being variable as to their eccentricity as well as to the direction
of their transverse axis they enable the velocipedist to vary the rotation of the pedal ;
according to his liking by causing its form to approach either a circle or a straight
line, as hereafter will be more fully described and shown.
แ
The principlo of the new crank is based on a proposition or theorem known from
kinematics and running as follows: "If the geometrical locus of the instantaneous
centre of rotation of a uniformly moving plain system" represents a circle described
by the said point with uniform velocity, but in the opposite sense of rotation of the
system" itself every point of the system runs along an ellipse the centre of which
coincides with that of the said circle.
I place on the bearing or driving axle a spur or cog wheel of a diameter suitable
to my purpose which is fixed to the frame of the tricycle and allows the bearing to
revolve through its centre, but cannot move itself.
To the said bearing or driving axle which projects a sufficient distance from the
spur wheel, 1 fix a crank (called the main crank) carrying at its other ei another
spur wheel of smaller diameter which is fixed to another crank (called the by-crank).
To this by-crank the pedal is fixed. An endless chain passes round the two spur
wheels, or may fix an intermediate spur to the main crank and dispense with the
chain.

page_text: Referring to the accompanying drawing, fig. 1 represents a longitudinal section of
the new crank, that is to say, of a single one fixed to the one end of the driven and
driving axle on the other end of which another corresponding crank is to be imagined
in a position exactly opposite to that of the first with regard to the alternative notion
of the feet. The figure representing the sectional view of the crank also shows it to
consist of several principal parts viz.
1. The primary or maincrank b, keyed upon the driving axle a, and bearing the
axle g
2. The secondary or by-crank c. keyed upon the axle g. and bearing the pedal 7. the
axle k of which is to be moved elliptically.
Fig. 3. shows plan of by and maincrank, c, by-crank, b. maincrank.
The driving axle a. may be borne by the nave of a non-turning toothe.l wheel d.
(or rather by two of them belonging to one pair of tread-cranks) fixel closely behind
the main-crank b. and fastened to the ring e, and by that to the frame of the
velocipede; this fastening may be executed with several adjusting screws f. which
allow the position of the wheel d. to be varied if circumstances require it or make it
desirable, or by any other manner of connecting the wheel d. to the frame.
A second toothed wheel h. half the size of the aforesaid wheel d. and having half
the number of teeth of the same pitch is fixed on the inner end of the by-crank-axle g,
by which it is united with the by-crank itself immovably.
Both of the wheels d. and h. gear together indirectly as shown by the figure 2
which represents the manner of offecting that gear. Figure 2 corresponds to fig. 1.
where the two wheels are supposed to be chain-wheels, gearing by means of an endless
pitch-chain. of any construction.
If the main-crank b. turns once round its axle a. the axis of the wheel h. and of tho
by-crank c. is carried along and describes a circle round the axis of the main-crank-
axle a. During a complete rotation of the main-crank, the wheel h., participating
in this rotation in the one direction and turning by impulse of the chain . twice
round its own axle g. in the opposite sense, compels the by-crank c. to perform one
real rotation contrary to that of the main-crank b. In consequence all parts of the
by-crank c, and especially the axle k. of the pedal move elliptically round the
driving axle a. There remains to be shown, how this elliptical rotation may be varied
as to the eccentricity, or the form of the ellipse described by the pedal 1, and to the
direction of its transverse axis.
Concerning the form of the ellipse a twofold arrangement has been chosen to effect
its variation. For the first, a series of slits e¹ have been arranged in the arm of the
by-crank c., as known from treail-cranks now in use, the axle k. of the pedal 7. being
pat through the slit nearer to one or the other end of it and screwed to the crank as
shown by fig. 1, and in combination with the slit, the axle k. is bent so that the pedal l.
may be disposed either nearer to or more distant from the axle g. than by turning it around
through 180 degrees. Both of these means combined admit to place the pedal Z, or
rather its axle k, on the crank c. at any desirable distance from the axle g. ; this
variability, being limited by the length of the slit and the amount of the inflection or
bend of the axle k, is much more considerable than that of the cranks now known and
used with circularly rotating pedals. As to the extreme positions of the pedals of the
new crank for velocipedes, care must be taken to rationally limit the above mentioned
distance of the pedal-axle from the by-crank-axle, in order to prevent its becoming
either quite equal to zero or quite equal to the length of the main-crank or middle
distance of the crank-axles a and g. The smaller that variable distance is arranged,
the more circular the form of the ellipse, making the pedals rotate in a manner more
and more resembling that of common circular cranks; and the longer that distance
between the axles gand k, the more flat the ellipse, finally almost degenerating into a
straight line of the double length of the diameter of the circle described by the axle g.
(At the end of this specification, applications of the new crank will be mentioned,
where the distance of the axle k, then representing the axis of a non-variable pivot,
from the axle g just equals the distance between the axles a and g).

page_text: .
Thus being able to vary to one's liking the form of the ellipses of the pedals from
circular ones to rectilinear ones, the direction of the transverse axis of the ellipses
admits of no change as long as the wheel d has not been loosened from the ringe and
fastened to it anew in another position, or the chain i (or the intermediate wheel) has
not been transposed on the wheel d, giving such a way an impulse to the wheel h,
causing it to make a turn, by which the by-crank c changes its position relatively to
the main-crank b, so as to turn the direction of the transverse axis of the pedal
ellipses. As represented by ligure 2 a full circle of holes for the screws fis arranged
in the plate or disc of the wheel d, ali of equal distances from each other. If the
position of the wheel dis varied by transposing the screws from hole to hole, the 1
direction of the ellipses is turned in the same sense and to the degree of the turn of
the wheel d.
The descriptions given above may be generally suitable to most cases, in which the
new elliptical crank will be adopted instead of common circular cranks; but of course
they are to be adapted to the particular construction and to the form of the frame of 1
the bicycle or tricycle to be provided with these cranks. According to the drawings,
no less than seventy-two (= 8 × 9) ellipses, different from each other as to their
form and the direction of the transverse axis will be at the option of the rider, who
will soon find out the one most convenient to him, and he may either employ the
same ellipse once for all, or in particular cases may choose any other ellipse that he
may think more appropriate to his special purpose. There cannot be any doubt, that,
for general use, flat horizontal ellipses, as most corresponding to, if not entirely
identical with, the motion of the feet habitual in walking, will render the least labour
and fatigue to the rider. Notwithstanding, other arrangements of the ellipses may be
preferred in some cases. Vertically arranged flat ellipses, e.g., will enablo the
velocipedist to reach an extraordinary velocity, his physical strength being efficaciously
supported and increased by the weight of his body; these ellipses therefore may be
chosen for races. Riders who are accustomed to common circularly rotating pedals
may begin with practising ellipses of a circle-like form, and by degrees change to
more flat ones.
As to the bearings of the axles a. g and k they may be constructed as either
cylindrical, or conical, or ball-bearings.
Having described my invention and its operation in application to tread-cranks for
velocipedes, I have to add but a few words with regard to other applications of the
new elliptical or straight-line-crank. Particular detailed descriptions of these applica-
tions in view will not appear to be necessary, since they require less complicated
arrangements than the cranks for velocipedes described. It will be sufficient to show
the manner in which the new crank can be applied to engines or receivers of
any kind in order to supersede cross-head guides and other arrangements of like
purpose.
If the by-crank c is provided with a simple pivot instead of a pedal, as repeatly
mentioned before, and the distance of the pivot from the axle g corresponds exactly
with the distance between the axles g and a, measured from axis to axis, the pivot
moves in ellipses degenerated into straight lines.
This oscillating motion can be put to use by connecting the piston-rod of the
cylinder of the machine directly to the pivot of the by-crank, no variability as to the
position of the wheel d. or the chain i, or the position of the pivot itself being needed
in this case. By this arrangement, all differences in the up and down stroke of the
piston as now existing are totally precluded, the uniformly variable motion of the
piston being exactly the same in both directions.
Having now particularly described and ascertained the nature of my said Inven
tion, and in what manner the samo is to be performed, I declare that what 1
claim is:
1. The improved crank, combining in its construction the maincrank b. (on the

page_text: or pedal; the non-turning toothed wheel d. (resting loose on the axle a. and fixed
to the frame of the machine); and the second toothed wheel A. of half the size and
half the number of teeth (on the axle g.). (by which it is united with the by-crank c.),
both of the toothed wheels d. and h. gearing indirectly together by means of either
an endless chain i or an intermediate wheel, pivotted on the main-crank b. by the
operation whereof, the pivot or pedal 1. is forced to move elliptically round the axle a.,
all operating in the manner set forth.
2. The arrangement and application of the bent end of the axle k. of the pedal 7.,
screwed to the crank c., in combination with a slit in the arm of the crank c. both
of these means admitting to place the pedal l. on the by-crank c. at variable
distances from the crank-axle 9, all constructed and operating substantially in the
manner set forth.
E. EATON & Co.,
Agents for Applicant.