An Improved Mechanical Arrangement particularly applicable to the Driving Mechanism of Cycles.
Year: 1896

page_text: Date of Application, 28th Sept., 1896-Accepted, 24th July, 1896
COMPLETE SPECIFICATION.
An Improved Mechanical Arrangement particularly applicable to
the Driving Mechanism of Cycles.
I, WILLIAM HENRY TRENGROVE, of 71 Cathedral Square, Christchurch, in the
Provincial District of Canterbury, in the Colony of New Zealand, Cycle 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:-
I will describe my invention as applied to the driving gear of Safety Bicycles, the
parts being substantially the same as those required upon other machines where a
similar result is to be obtained.
The rider of the bicycle operates pedal levers, which are arranged to vibrate either
in bearings or upon rocking spindles supported in the bottom bracket of the
machine.
Each pedal lever is provided with a cam, which is either made integral with, or
adjustably connected to it, and flexible connecting rods connect these cams with
cranks upon a spindle which is thereby caused to revolve and give motion to the
driving wheel of the machine.
The invention consists in the novel combination of the levers, cans, flexible
connecting rods and cranks, and the object is to arrange the shape of the cams and
their position in relation to the levers and cranks respectively, so as to produce the
best mechanical effect in actuating the machine.
Referring to the accompanying drawings in which similar letters of reference
indicate the same parts throughout the figures:-
Figs. 1 and 2 are respectively a side elevation, and plan of a Safety Bicycle..
illustrating my invention.
Figs. 3 and 4 similar views, illustrating its application to a lady's safety bicycle.
Figs. 5, 6, and 7 are diagrammatic. views, illustrating the parts in different
positions.
Figs. 8 and 9 are respectively a side elevation and plan showing a cam adjustably
connected, so that its position may be regulated in relation to the lever to which it
is attached.
Referring first to Figs. 1 and 2, the pedal levers (a) (b) of the bicycle are pivoted
upon the spindle (c) in the bottom bracket of the machine so as to vibrate through
the arc indicated in dotted lines in Fig. 1. The cam pieces (a¹) (61) are made
integral with the levers (a) (b) respectively.
The chain wheel (e) is mounted in a bearing (f) secured to the frame of the
machine and is connected by an ordinary drive chain (f) with the pinion (g) upon
the axle of the driving wheel.
The ends of the axle (el) of the chain wheel (e) are respectively provided with
cranks or levers (h) (i) arranged opposite to each other and to the ends of which
are pivoted connecting rods () (), having flexible portions (m) (n) (which may be
made of steel drive chain) connecting them to the inner peripheries of the
cams (a) (b) respectively.

page_text: In Figs. 3 and 4 the chain gearing (f) (f') (g) is dispensed with and the
cranks (h) (i) connected directly to the axle (el) of the driving wheel.
The operation of the mechanism will be more clearly understood by reference to
Figs. 5, 6 and 7. In Figure 5 the end of the crank (h) is at the highest or top
dead centre in its revolution and: the lever (a) at the top of its stroke; the flexible
end (m) of the connecting rod (k) is now pulling from the bottom of the cam (a')
which is thus the shortest arm of a levér, the other arm of which is the lever (a).
During the travel of the crank from the position indicated in Fig. 5 to that
indicated in Fig. 6, namely, one-fourth of a revolution, the flexible end (m) of the
connecting rod () has been wound upon the periphery of the cain (a), so that the
mechanical efficiency of the lever (a) has been constantly diminishing. The flexible
connecting rod (m) now passing over the end of the cam, the operation during the
progress of the crank to the position shown in Fig. 7 is the same as if the connecting
rod () were pivoted to the end of a lever of a length equal to the cam (a¹).
Instead of making the cams integral with the levers it may be desirable to
connect them adjustably, as illustrated in Figs. 8 and 9; the lever and cam being
formned separately, the lever having arc-shaped projections (p) upon either side
between which the cam (a), having a similarly shaped projection (); is clamped by
a bolt (t) passing through corresponding holes in the projection (p) and a slot in the
projection (1).
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. In mechanism for driving cycles, the combination with a vibrating lever to
which the power is applied of a cam integral with, or adjustably secured thereto, a
flexible connection, one portion of which winds upon the periphery of the cam,
connecting the cam to a crank upon an axle, which is thereby caused to revolve and
to propel or actuate the machine, substantially as and for the purposes described
herein and illustrated.
2. In combination the lever (a), cam (a¹), connecting rod (k) having a flexible
end (m) and the crank (h) upon the axle (e¹) as specified and illustrated.
3. In driving mechanism of cycles the cam made separate from and adjustably
connected to the lever to which the power is applied substantially as and for the
purposes specified and illustrated in Figs. 8 and 9.
4. In driving mechanism of cycles, the combination and arrangement of parts
substantially as and for the purposes herem described and illustrated in the
accompanying drawings.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.