Improvements in and relating to Expanding Cranks for Cycles and other Vehicles.
Year: 1898

page_text: Date of Application, 15th Mar., 1898-Accepted, 14th May, 1898
COMPLETE SPECIFICATION.
Improvements in and relating to Expanding Cranks for Cycles and
other Vehicles.
We, Dr. SALOMAN LICHTENSTEIN, Physician, of 10, Engerserstrasse, and PAUL
SCHROTER, Sculptor in Wood and Stone, of 25, Feldkirchenstrasse, both of Neuwied
a/Rhein, in the Empire of Germany, 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:-
The present invention relates to a driving mechanism for cycles and other vehicles,
and it is characterised by the arrangement of eccentrically mounted discs or cranks
whose eccentricity can be varied at will within certain limits, so that at each
revolution the operative crank has a greater length than the inoperative and
upwardly moving crank, and so that also the length of the operative crank can be
adjusted to any gradient according as the said gradient becomes more or less
steep. The subject of the invention is illustrated in the accompanying drawing, in
which Figure 1 is a side elevation of an arrangement of pedal crank; Figure 2,
is a plan partly in section of Figure 1; Figure 3 shows in side elevation a some-
what modified form of construction, whilst retaining the same principle. Figure 4
is a horizontal section of Figure 3.
In Figures 1 and 2, a are eccentric discs which are fixed on the pin b so as to be
not capable of rotation. Upon each of these eccentric discs, there works in the
usual manner upon balls or by other suitable means an eccentric strap d. The
latter is formed with a shoulder e in the hole of which there is fixed the pin of a
pedal f. The pedal f can move to and fro in the slot of the crank o, which is
rigidly fixed to the pedal crank axle %. When the eccentric strap is turned round,
it will be clearly understood that in consequence of the eccentric mounting, a long
leverage will come into operation, such for example, when depressing the crank as
illustrated in the right hand of Figure 1, whilst in the opposite position, that is
to say, in the ascending movement, the length of said leverage will be considerably
shorter.
In the middle of the eccentric disc a is formed a slot adapted to receive square
block, through which the crank axle passes. If it be now desired to alter the
eccentricity, that is to say the length of leverage of the crank, the screws pare
loosened, and the two eccentric discs are moved in one or the other direction to such
an extent that the crank axle k will be moved to a greater or less extent, nearer to
or further from the centre of the eccentric disc. When the crank axle passes
through the centre of the eccentric disc, both cranks, that is to say, both the rising
crank and the descending crank, are of equal length. This arrangement has there-
fore the great advantage that the lengths of the cranks can be made longer or
shorter according to the gradients to be mounted.
A somewhat modified construction is shown in Figures 3 and 4. In this case
both eccentric discs are rigidly fixed to the pedal cranks, or are formed in one piece
therewith. The eccentric discs work in rings t, which are mounted so as not to be
capable of rotation on the crank bearing. The crank axle k is connected only by

page_text: means of square parts with each crank, which parts engage in slots in the cranks.
The chain wheel is not mounted directly upon the crank shaft k, but runs on balls
on the outside of the crank bearing 7. The cranks are provided with slots n, and
are connected with the chain wheel by means of a pin m screwed fast to the same,
in such a manner that the outer end (which is provided with a roller) of the pin,
is capable of moving to and fro in the slot n in the direction of the length of the
latter. If one crank be depressed, the eccentric dises a move on the balls and take
at the same time the crank axle k round with them. At the same time the chain
wheel r is carried round by the pin m. By reason of the eccentric bearing of the
cranks, the pin m moves as already stated, to and fro in the slots n of the cranks,
so that also a shorter and a longer leverage of the cranks must necessarily take
place alternately.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is:-
(1) An expanding crank for cycles and other vehicles characterised by two
eccentric discs a, which are carried in a non-rotatable manner by means of a cross-
piece which is adjustable in a longitudinal direction on a fixed rod c, said eccentric
discs being adapted, by means of the slots e running parallel to the rod c, to embrace
the crank axle, whilst the eccentric rings d render immovable the pedal pins which
engage in longitudinal slots of the cranks o.
(2) A modified form of expanding crank specified in Claim 1, characterised by
the fact that the crank arms themselves carry the eccentric discs a, whilst the
latter themselves rotate in rings which are inmovably fixed to the cycle frame, and
the arrangement being such that the connection of the chain wheel r working
loosely outside on the crank bearing 9 is effected with one of the cranks (which are
connected together by means of slots and a square part in such a manner as to
transmit power) by means of a fixed transverse arm of the wheel
which arm
engages in a longitudinal slot n of said crank.
(3) The improvements in expanding cranks for cycles and like vehicles substan-
tially as hereinbefore described and shown.
OBERT E. PHILLIPS, Assoc. M. Inst. C.E., M.I.Mech.E.,
Consulting Engineer and Patent Agent,
70, Chancery Lane, London, W.C., Associate Agent.