Improvements in and relating to Driving Mechanism for Bicycles.
Year: 1898

page_text: Date of Application, 16th May, 1898-Accepted, 30th July, 1898
COMPLETE SPECIFICATION.
Improvements in and relating to Driving Mechanism for Bicycles.
We, THOMAS RUTLEDGE ALEXANDER, of Linwood, Canterbury, New Zealand,
Bicycle Manufacturer, and CHARLES GRIFFIN-BEALE, of Gympie, Queensland,
Gentleman, but both at present of 109, Pitt Street, Sydney, New South Wales,
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 follow-
ing statement:-
This invention relates more particularly to the driving gear of bicycles, such
driving gear necessitating modifications in the construction of the frame, whereby
the machine has a considerably reduced wheel base and is rendered much more
compact and easily managed.
In the accompanying drawings:-
Fig. 1. Is a side elevation of the machine, shewing the improvements.
Fig. 2. Is a sectional plan of the same, on the line 1-2 of Fig. 1, but with the
frame entirely removed.
Fig. 3. Is a sectional end elevation of the frame taken on the line 3 4 of Fig. 1,
and viewed from the left towards the right.
In the machines at present in use, the main driving sprocket wheel has its axis
between the peripheries of the two wheels of the bicycle, such axis being placed at
the point of junction of the seat pillar with the diagonal brace.
In this invention the axis of the main driving sprocket is moved so far rearwards
as to lie within the circumference of the driving wheel, and the axle of the main
driving sprockets must therefore be divided, half of such axle being on each side
of the driving wheel. It is, therefore, necessary to fork the seat pedestal, and also
the diagonal brace, so that one half of each fork shall unite at a point on each
side of the driving wheel, and at or near such point or points supports for the
axes of the two main driving sprockets shall be provided.
A is the seat pedestal which is forked at a a, B is the diagonal brace which is
forked at 6 b, one arm a and b of each uniting at a point on each side of the
driving wheel C at or near which point may be arranged a support for the axis
of the main driving sprocket D.
In this way the main driving sprockets I) are brought much nearer than usual
to the sprocket pinions on the axis of the driving wheel C. In the drawing this
axial sprocket E is made larger than usual, for the purpose of better illustrating
the invention. As may be seen by reference to Fig. 2, there are two main
driving sprockets D), and two axial driving sprocket pinions E, one of each, on
each side of the driving wheel C. The axial sprocket pinions are on the axis of
the driving wheel C, but it is necessary that the axle of the driving sprockets 1)
should be divided, or made in two halves, one on each side of the driving wheel C.
These axles are supported by the hubs at the points of junction of the arms A
and B.
The two parts of this divided axle are fixed firmly within the hub and the main
driving sprockets D are made to revolve thereon.
Extension pieces F F, one on each side of the driving wheel C, extend from the.
hub at the point of union of the forks a and b rearwards, past the axis of the

page_text: driving-wheel C so as to form a frame support for the axle of the driving wheel C.
A forked back stay G serves as a support between the upper end of the saddle
pillar A and the rear ends of the extension pieces F, thereby giving extra rigidity
to the frame.
The main driving sprockets I) are provided with the usual pedals H as in
ordinary machines.
The distance between the axis of the main driving sprocket D and the axis
of the sprocket pinion E having been very greatly shortened, the sagging and
swaying of the chain J will be reduced to a minimum and more satisfactory results
will ensue.
Instead of the saddle pillar A and the diagonal brace B being forked as shown
in the drawings, these parts may be made double throughout. The reductia in
the length of the wheel base is a very important element in the invention and will
assist the rider to a great extent by largely reducing his physical labor.
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. In bicycles, a forked saddle pillar and a forked diagonal brace, in combina-
tion with two driving sprocket wheels and two driving sprocket pinions, one of
each on each side of the driving wheel, that are supported by the forks, the axes
of such driving sprocket wheels being placed so as to lie altogether within the
rim of the driving wheel and such sprockets on the same side being geared together
by means of chains, as herein set forth.
2. In bicycles, a forked saddle pillar and a forked diagonal brace, the arms of
the forks of which meet in a hub on each side of the driving wheel, in combination
with sprocket wheels and pinions, geared together by chains, one pair of sprockets
being on each side of the driving wheel, the axes of the sprocket wheels being
supported by the hubs at the points of junction of the arms of the forks, as
specified.
Dated 29th March 1898.