An Improved Variable Throw Crank.
Year: 1895

page_text: Date of Application, 18th Jan., 1895
Complete Specification Left, 18th Oct., 1895-Accepted, 23rd Nov., 1895
PROVISIONAL SPECIFICATION.
An Improved Variable Throw Crank.
I, JOHN RAU, a citizen of the United States, residing at 333 Center Street,
Chicago, in the County of Cook, and State of Illinois, one of said United States,
Mechanic, do hereby declare the nature of this invention to be as follows:-
This invention relates to that class of mechanical movements in which the crank
is the principle factor and its object is to provide means whereby the length of the
crank from the pin thereof to the centre of the shaft, to which the crank is attached,
may be increased and decreased during each revolution of the shaft as hereafter
described.
The mechanical movement may be applied for various purposes as for example,
say, to a bicycle. To the boss of say an ordinary safety bicycle-in which the
usual crank shaft is mounted to revolve-is firmly secured an eccentric fitted with,
so as to revolve freely, an eccentric yoke or strap. The yoke or strap is provided
with a pin firmly secured thereto and which projects outwardly. At the outer end
of the crank shaft is firmly secured a slide block which is fitted to slide freely in the
slot of the crank which is pivotably mounted at on end to the projecting pin. The
crank pin has mounted thereon an ordinary bicycle pedal.
The operation of the movement is as follows:-
The shaft is caused to revolve by the crank because the block is securely attached
to the shaft, and in only sliding engagement longitudinally with the slot; being
compelled to revolve with the crank whose length is gradually increased by having
one end thereof pivotably attached to the yoke or strap which is revolved by the
crank around the fixed eccentric and is thereby slid upon the block alternately
centrifugally and then centripetally. When used, say for a bicycle the crank is
made to attain its greatest length when forward of the driving shaft.
It is obvious that the construction of this mechanical movement may be changed
considerably from what is described without materially departing from the spirit of
the invention; as for instance, the eccentric may be fixed at any angle to the
horizontal, or for any other particular purpose, also, the crank may be made
straight without the slot and be fitted to slide in a longitudinal slot or groove in the
block, should such a construction be found more efficient.
Dated this Seventeenth day of January 1895.
JOHN RAU,
By W. Fairburn-Hart,
Agent.
An Improved Variable Throw Crank.
I, JOHN RAU, a citizen of the United States, residing at 333 Center Street,
Chicago, in the County of Cook, and State of Illinois, one of said United States,
Mechanic, 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 that class of mechanical movements in which the crank is

page_text: bicycle.
Figure 2, is a plan view.
Figure 3, is an elevation of an eccentric yoke, and
Figure 5, is a plan of the same.
Figure 4, is an elevation of an eccentric which is fitted to receive the yoke shown
in Figure 3.
Figures 6 and 7, are side elevations with the operative parts shown in positions
different from what is shown in Figure 1.
Figure 8 shows, respectively, side and edge views of the crank, and
Figure 9, is a plan of the crank shaft with a slide block permanently attached at
one end.
Figures 3 to 8 inclusive, are drawn to a scale one half that of Figures 1 and 2.
Similar letters indicate like parts throughout the several views.
The drawings show this mechanical movement attached to the frame of a bicycle,
a part thereof being shown in Figures 1 and 2, in which A is the boss of an
ordinary safety bicycle in which the usual crank shaft B is mounted to revolve.
At C is an eccentric which is firmly secured to the boss A, and D is an eccentric
yoke fitted to revolve on the eccentric C, the yoke D having a pin E firmly secured
thereto and which projects outwardly, Figs. 2 and 5.
At the outer end of the crank shaft B is firmly secured a slide block F, which is
fitted to slide in the slot G, of crank H which is pivotally mounted at one end to
the projecting pin E. The crank pin J has mounted thereon the ordinary bicycle
pedal device K. The braces of the frame of the bicycle are shown at L, M, N
and O, but the chain wheel and the crank for the opposite side of the bicycle are
not shown for obvious reasons.
In operation, the shaft B is revolved by the crank H because the block F is
securely attached to the shaft, and in only sliding engagement longitudinally with
the slot G; being compelled to revolve with the crank whose length is gradually
increased and decreased in each revolution by having one end thereof pivotally
attached to the yoke D which is revolved by the crank around the fixed
eccentric C, and is thereby slid upon the block F alternately centrifugally and then
centripetally to the positions shown in Figs. 1 and 6, one of the intermediate
positions being shown in Figure 7.
For use in a bicycle the crank is made to attain its greatest length when forward
of the driving shaft B, Figures 1 and 2, the arrow showing direction or
revolution in making the down stroke, the shortest length being shown in Figure 6.
It is obvious that the construction of this mechanical movement may be changed
considerably from what is shown and described without materially departing from
the spirit of the invention; as for an instance, the eccentric C may be fixed at any
angle to the horizontal, than what is shown when applied to a bicycle, or for any
other particular purpose, also, the crank H may be made straight without the
slot G and be fitted to slide in a longitudinal slot or groove in block F, should such
a construction be found more efficient.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, 1 declare that what I
claim is :-
A mechanical movement comprising a revoluble shaft with a slide block firmly
secured thereto, a non-revoluble circular body fixed around said shaft and in a
plane at a right angle and eccentric thereto, a yoke fitted to revolve on the circular
body, one end of a crank pivotally attached to one side of the yoke and fitted to the
slide block to revolve the shaft and to slide longitudinally upon or within the slide

page_text: block, whereby the revolution of the crank causes the shaft to revolve and the yoke
to revolve around the circular body and slide the crank alternately centrifugally
and then centripetally in each revolution thereof, substantially as shown and
described.
Dated the Seventeenth day of October 1895.
JOHN RAU,
By W. Fairburn-Hart,
Agent.