Improvements in Variable Speed Gear for Cycles.
Year: 1898

page_text: Date of Application, 25th Aug., 1898-Accepted, 12th Nov., 1898
COMPLETE SPECIFICATION.
Improvements in Variable Speed Gear for Cycles.
I, KARL MANKE, of 27, Stralsunder Strasse, Berlin, in the German Empire,
Mechanical Engineer, 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, reference being had to the accompanying
drawings and to the letters and figures marked thereon, that is to say: -
This invention relates to variable speed gear for cycles, whereby changes in
speed can be readily effected whilst the machine is in motion.
The main advantage of my invention is that a simple back pressure exerted upon
the cranks, without stopping the machine, will suffice to cause the change of gear,
whilst when such back pressure is exerted, the mechanism acts as a break.
According to my invention, the change of gear is effected by a simple back-
pedalling operation, that is to say, by pressing the pedals in a direction opposite
to that for propelling the machine.
To this end one of the cranks is connected with a set of pinions arranged between
the chain-wheel and a central toothed wheel which can be connected, by the means
hereinafter described, either rigidly to the cycle frame, or can be put into rotary
connection with the said crank.
In the accompanying drawings:
Fig. 1 is a longitudinal section illustrating one construction of the improved
gear and taken through the chain wheel on the line a, a of Fig. 2.
Fig. 2 is a section on the line y, y of Fig. 1.
Figs. 3 and 4 are elevations shewing in two positions a clutch device employed
with this arrangement.
Fig. 5 is a side elevation shewing the crank in connection with the pinions.
Fig. 6 is a longitudinal section through the chain-wheel, illustrating a modified
arrangement, and
Fig. 7 is a section on the line z, z, of Fig. 6.
Referring more particularly to Figs. 1 to 5, a is the chain wheel, having internal
teeth, 6 the central toothed wheel, and c', c³, c³, the pinions arranged between these
wheels. is the crank with which the said pinions are connected.
d', d, d³, are screw studs arranged (concentrically with the crank axle g) on
the crank, and on arms projecting therefrom. In connection with these studs are
ball bearings for the pinions c¹, c³, c³, while a flanged ring n, hereinafter referred
to, is secured to them by screws u¹, u³, u³.
i is the barrel of the bracket in which the crank axle works. On it are mounted
two similar rings or collars o, ob, of which o" is fixed whilst ob is capable of
rotating.
Supposing the central wheel b, which is mounted on ball bearings on the crank
hub, is connected, as hereinafter described, with the rings o", ob, it will remain
stationary, and the pinions c', c³, c³, will travel round it when the cranks are
operated, whereby the chain-wheel a will be driven more rapidly than the cranks,
and the high gear will be obtained.

page_text: If, however, the central wheel b, be connected with the flanged ring n
on the
pedal crank, the said wheel will then turn with the pinions, and the latter will be
prevented from revolving on their axes. Thus the normal and low gear will be
obtained, the chain wheel revolving at the same speed as the cranks.
For the purpose of connecting the toothed wheel b, either with the flanged
ring n, or with the rings o", ob, I employ the following arrangement: A flange b¹
on the said wheel carries a pawl m, pivoted at m¹ and adapted to engage either
in notches o in the rings o ob or in a notch n in the ring n. A coiled spring /
is provided to keep the pawl in one or other of its extreme positions. This spring
is secured at 1 and 2 to the flange b¹ and the pawl respectively, and accordingly
will press towards one side or the other of the dead centre of the pawl as the latter
is turned on its pivot.
Supposing the pawl to be engaged, as in Fig. 3, with the rings o", ob, to keep
the wheel 6 stationary and give the high gear, and that the rider desires to change
to the low gear, he simply back-pedals slightly, whereupon the chain wheel a,
reacting through the pinions c1, c2, c³, causes the central toothed wheel b to move
in the opposite direction, carrying the pawl m backward out of the notch o. The
pawl is thereby partly turned on its pivot, so that when it arrives opposite the
notch n in the outer ring n it snaps into the same.
1
Under these conditions, the flange 6 and also the toothed wheel b are coupled
with the flanged ring n, and thus rigidly connected with the crank d.
After the pawl m has fallen into the notch n in the ring n, the movable ring ob
is, by means of a spring o°, caused to turn to such an extent, relatively to the fixed
ring, that the notches in the rings are no longer in line with each other, as
shewn in Fig. 4.
If now pedalling in a forward direction be resumed, the pawl m engaged in the
notch n will be carried along by the ring n which thus becomes coupled with the
flange 6 of the wheel b. The latter and the pinions c¹, c², c³ are, in this manner,
rigidly locked together, so that the pinions no longer revolve either on the toothed
wheel b or upon the internal teeth of the chain-wheel a. The low gear is thus
obtained.
But in order to again obtain the high gear, the cranks are back-pedalled, and
the pawl m, under the action of the oblique surface of the notch n³, is forced
against the edges of the rings o", ob, and while it continues to slide thereon the
two notches in o, ob will again be caused to coincide. Thereupon the pawl m,
still under the pressure of the oblique surface, will fall into these notches and
the change of gear will thus be effected.
These actions are repeated each time the cranks are back-pedalled, or turned
in a backward direction.
Referring now to the alternative arrangement shewn in Figs. 6 and 7, it will
be seen that whereas in the former arrangement the low gear is the simpler form
of transmission, in the arrangement now under consideration the high gear is the
simpler.
In this case, an internally toothed ring e is fixed to the crank d, and on the hub
of the latter is arranged the toothed wheel 6 which is adapted to rotate on ball
bearings. Between this toothed wheel b and the toothed ring e, revolve four
double pinions c¹, 3. The larger part 2 of each pinion engages the ring e, whilst
the smaller part c¹ engages the wheel b.
The notched rings o, ob, are connected with the crank instead of with the
barrel i, and in place of the ring n a stationary disc o is secured on the barrel i.
The chain wheel a is arranged concentrically with the toothed wheel 6 and has
internal teeth which gear with the small pinion c¹.
Said wheel b is provided with two pawls m, one on its inner and the other on its
outer side, which are connected with each other, and are so arranged that they
fulfil the same function as the single pawl m in the first arrangement. According
as they connect the central wheel b with the rings oº, ob, or with the disc o, 80
the high or the low gear is obtained.

page_text: 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. A variable speed gear for cycles, in which pinions connected with one of the
cranks and gearing with internal teeth on the chain wheel, are disposed around
a central toothed wheel which can be connected at will with the frame of the
machine or with the said crank, the change being effected by back-pedalling,
substantially as described.
2. In a variable speed gear for cycles, as above claimed, the pawl and notched
rings combined and operating substantially as described, for the purpose of con-
necting the central toothed ring with the part required.
3. The modified arrangement in which the pair of notched rings is fixed to the
pedal crank and a stationary disc is arranged on the barrel of the bottom bracket,
substantially as described.
4. My improved variable speed gear for cycles, substantially as herein before
described with reference to Figs. I to 5, or to Figs. 6 and 7, of the annexed
drawings.
Part
CHID SOUL viary
1000
ERNEST DE PASS,
Chartered Patent Agent,
78, Fleet Street, London, and 5A, Market Street, Nottingham,
Agent for the Applicant.