Year: 1888

page_text: Date of Application, 26th July, 188
Specification Accepted, 31st Aug., 1888
Empire of Germany, Gentleman.
I, ALFRED JULIUS BOULT of 323 High Holborn in the County of Middlesex, M.I.M.E.
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 adjustable transmission gearing particularly though
not solely applicable for velocipedes, which will enable the rider to change the normal
speed into a slower or faster one, when desired, without altering the speed of the crank
axle, by varying the proportion thereto of revolutions of the driving axle.
In the accompanying drawings:
Fig. 1 represents the adjustable transmission gearing in side elevation, in the
position for the normal speed.
Fig. 2 represents a plan partly in section of the same.
Fig. 3 represents an end elevation of one of the adjustable pitch wheel teeth.
Fig. 4 represents a perspective view of the same.
Fig. 5 represents a front elevation of the guide for the adjustable pitch wheel
teeth.
The invention consists essentially in mounting two pitch-wheels of different diameter
on the crank axle T and two similar pitch-wheels on the driving axle A in such a
manner that the larger wheel of one axle will be connected with the smaller wheel of
the other by the pitch chain K or vice versa.
The pitch-wheels mounted on the crank axle communicate their movement by
means of the pitch chain K to the pitch wheels mounted on the balance box B which
contains the balance gear D for the coupling of the axles A.
When the speed is to be altered one of the larger pitch-wheels must be moved into
the plane of the smaller pitch-wheels and the chain, while the other larger wheel must
be moved out of this plane. The pitch of the teeth of the larger and smaller wheels

page_text: and of the links of the chain must be the same, while the diameters of the larger and
smaller wheels are in proportion to the desired transmission, in the drawings this
proportion is represented as 1 to 2 for instance the smaller wheel may have 9 teeth
and the larger one 18 teeth.
As for comprehensible reasons it is not desirable to move the whole of the large
wheels R R on their axles in and out of the plane of the chain K the teeth Z of these
wheels are made movable. The rims of the wheels R R' are formed with
grooves in
which slide the shanks N of the teeth and a ring or hoop r retains the shanks in the
grooves. At the further end the shanks N are provided with projections M which
pass through the forked guides G attached or formed at the ends of the pivotted
lever H. This lever is pivotted at and can be moved by the rider while the
machine is in motion in such a manner that for instance the teeth Z of the wheel R¹
are one after the other moved into the plane of the chain K by the guide G so that
the chain gradually passes from the smaller wheel to the larger. At the same time
the teeth Z of the larger wheel R are moved out of the plane of the chain and the
chain will pass from the larger on to the smaller wheel.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me
by my foreign correspondent, I declare that what I claim is :-
1. The employment in a transmission gearing of two pairs of pitch wheels adapted
to gear with a pitch chain the larger wheels having adjustable sliding teeth which are
moved into or out of the plane of the chain in such manner, that the chain always
passes over one of the larger and one of the smaller pitch wheels substantially as and
for the purpose described and illustrated in the accompanying drawings.
2. The combination with the transmission gearing as set forth in the above claiming
clause of a pivotted lever such as H having a forked guide such as G at each end
substantially as and for the purpose described and illustrated in the accompanying
drawings.
D
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