Improvements in Pedal-lever Driving Gear.
Year: 1898

page_text: Date of Application, 26th July, 1898-Accepted, 26th July, 1893
COMPLETE SPECIFICATION.
Improvements in Pedal-lever Driving Gear.
We, MATTHÉE PAUL HERFURTII, of 9, Arndtstrasse, Chemnitz, and HEINRICH
RICHARD BERTHOLD, of 117, Zwickauerstrasse, Chemnitz, both in the German
Empire, Manufacturers, do hereby declare the nature of this invention, and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement:-
This invention relates to a pedal-lever driving gear, more especially applicable
to cycles and other similar vehicles, but applicable also generally to machinery
driven by pedal-lever gear. According to this invention the two pedal-levers
turn two cranks which are independent of one another, and actuate driving wheels
arranged excentrically with regard to such cranks, but rotating at the same speed,
whereby, in the case of cycles and so forth, increased speed or increased facility
of going up hill can be obtained. This action is increased by the fact that the
connecting rod does not stand at right angles to the pedal-lever when in the middle
position, but in an inclined position with reference thereto. By this arrangement
the force exerted upon the pedal-lever by the rider is resolved into two com-
ponents, of which the one that coincides with the direction of the connecting rod
acting upon the crank is always materially greater than the force exerted by the
foot upon the pedal-lever.
In the accompanying two sheets of drawings:-
;-
Figure 1 is a side view of a wheel with the improved driving gear applied
thereto.
Figure 2 is a side view of certain details of the driving gear to be hereafter
described, and
Figure 3 is a vertical section of the detail shown in Figure 2.
In Figure 1a al are the two pedal-levers furnished at their free ends with a
short outwardly bent arm. These pedal-levers are pivotted one at each side of
the frame at A near the axis of the hind-wheel, are the treadles. To the
free ends C of the levers a a¹ are pin-jointed the connecting rods b b which
transmit the up and down movements of the pedal-levers to the cranks c c¹
(Figures 1 and 2), and cause the latter to rotate continuously. These cranks are
pivotted to the frame of the cycle in the manner shown in Figure 2, or in any
other suitable manner, and so as to be independent of one another. In the
arrangement shewn in Figure the crank is mounted on a spindle c² free to
turn in a bearing in the frame of the machine; and the crank c is mounted so as
to be free to turn on a bearing concentric to c² but independently of the crank c¹.
Both cranks are connected by links h¹ with spur wheels or spur wheel rims d d¹
which rotate on fixed discs or bearings H, which are eccentric to the axis of
rotation of the cranks cc. In Figures 2 and 3 the link his shewn connected to
an arm extending from the boss of the crank c. This method of connexion
of the link to the crank c is employed when, as in the figures the chain wheel f
is too large to allow a direct connexion to pass it. The two wheels or wheel
rims gear with toothed wheels e e¹ connected rigidly together so that they

page_text: e
always rotate at the same angular velocity. The transmission to the hind-wheel
of the cycle of the motion communicated to the wheels d d by the rotation of
the cranks e c¹ is effected, in the example illustrated, by means of a chain and
two chain-wheels f and g. The chain-wheel f is connected rigidly to the toothed
wheels e e¹ by means of a shaft F as shown in Figure 3.
As the two wheels d d are always caused by the wheels
to rotate at the same speed as one another, there is no absolute
necessity to couple the wheelf with the wheels e e¹ as it may, if preferred, be
connected rigidly to one of the wheels dd. The direction in which
the wheels d d rotate is shown in Figure 1 by an arrow; when, however, the large
chain-wheel is connected with one of the wheels d the rotation of those
wheels would be in the opposite direction. The position of the eccentric H, must
in this case be altered from that shown in Figures 1 and 2, so that it stands at
about the same angle to the horizontal to the right hand as.it does to the left in
the figures. The arrangement of the wheels d d eccentric to the axis of rotation
of the cranks cc' forms a special feature of this invention; as by its means when
the pedal-lever is in the highest and lowest positions, the two cranks are not
diametrically opposite to one another; but, as shown clearly in Figures 1 and 2,
include between them an angle which may be considerably smaller than 180°.
The downward movement of each pedal-lever rotates each corresponding crank
to the extent of the angle y only (see Figure 2), notwithstanding the fact that
the crank, in consequence of its connection with the wheel or by means of
the link h or h¹ turns the said wheel d or d fully 180°. The effect of this is that
the turning power exerted on the crank pin is correspondingly greater than it
would be if the crank had rotated through the angle y plusz, that is to say 180°.
The turning moment acting upon the hind-wheel is consequently greater, and
the cycle therefore receives a more powerful impulse, which produces greater
speed and facilitates travelling up hill.
"
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is:-
First. Improved pedal-lever driving gear, the essential features of which are
that the pedal-levers a a are connected by connecting rods bb₁ with cranks
which are independent of one another, which cranks carry with them in their
rotation, by means of links h h¹, driving wheels or wheel rims d d arranged
excentrically with reference to the axis of rotation of the cranks and which
driving wheels or wheel rims are caused to rotate at the same speed as one
another by means of coupled toothed wheels e e¹, substantially as described.
Second. In pedal-lever driving gear of the kind forming the subject matter
of the first claiming clause hereof, the arrangement of the connecting rods at a
considerable inclination, that is to say at an acute angle, to the pedal-levers, so
that the components of the forces exerted on the pedal-levers which act through
the said connecting rods are always greater than the said forces, substantially as
described.
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