Improvements in Driving Mechanism for Bicycles.
Year: 1897

page_text: Date of Application, 24th Dec., 1897-Accepted, 26th Feb., 1898
COMPLETE SPECIFICATION.
Improvements in Driving Mechanism for Bicycles.
I, OLIVER IMRAY, of Birkbeck Bank Chambers, Southampton Buildings, in
the County of London, Chartered Patent Agent, do hereby declare the nature of
this invention (which has been communicated to us from abroad by William Davis
Smith, of Denver, in the County of Arapahoe and State of Colorado, Bicycle
Manufacturer, United States of America) and in what manner the same is to be
performed to be particularly described and ascertained in and by the following
statement:
My invention relates to driving mechanism for bicycles which I shall describe
referring to the accompanying drawings.
Figure 1 is a side elevation of a safety bicycle provided with one form of the
improved driving mechanism; Figure 2 is a plan, partly in section; Figures 3, 4,
5 and 6 shew details on a larger scale, Figures 7 and 8 shew the clutch mechanism
on the nave of the rear wheel. Figures 9 and 10 shew the bearing for one of the
driving levers, Figure 11 is a partial side elevation showing devices for attaching
the pulley-cord, Figures 12 and 13 are similar views of driving connections
between the driving levers and driving wheel; Figure 14 is a partial side elevation
of a bicycle provided with another form of the mechanism and Figure 15 is a plan,
partly in section, showing the arrangement of the driving cranks in Figure 14.
Referring first to the form shewn in Figures 1 to 11 inclusive), 2 is the frame
of a safety bicycle, with front wheel 3 and rear wheel 4. It is worked by a pair
of driving levers 5, 5, each of which has a pivot fixed in the axle-hanger 7, so that
they operate independently of each other. Surrounding the journal or axle 6 is
a thimble 11, (Figure 9) at each end of which, between the thimble and the axle,
is a set of ball bearings placed in recesses at each end of the thimble; the thimble 11
is held on the axle by a nut and washer, and a dust cap 13, is screwed onto the
thimble against a washer 12, which surrounds and is fastened to the socket of the
driving lever 5. The flange of the dust-cap 13 also covers an oil hole.
washer 12 has also, preferably, two notches or recesses 10, on opposite sides, not
necessarily extending through it, which coincide with two notches in the driving
lever, to receive two correspondingly projecting radial lugs on the thimble 11,
the lugs 10 projecting sufficiently to engage the notches in the washer 12. Each
driving lever is provided with a projecting pin 14 on its inner face (Figures 5
and 6), which enters an arc-shaped slot 15 (Figure 10) in the face of the axle-
hanger 7, thus forming a stop to limit the stroke of the driving lever, and to afford
a rest for the foot of the rider, without interfering with the rotation of the driving
wheel.
The
To the rear arm of the driving lever 5 is pivoted a swinging link 16, on which is
pivotted a grooved pulley 17. The link 16 has at its upper end an outwardly
projecting pin 18 to be engaged by the foot of the rider when it is desired to change
the gear. Passing around the pulley 17 is a belt or wire rope 19 (Figures 1 and 2),
which has one end fixed to the frame at 20, and at the other end is wrapped around
the pulley 21, of a friction clutch, surrounding the shaft of the rear wheel. This
drum (Figures 7 and 8) has a flange 22, with inclined notches 23, containing short

page_text: rollers 24.
This flange is enclosed in the rim 25, of the nave 26, of the rear wheel,
this rim acting as a friction clutch in conjunction with the rollers 24, moving in
the inclined notches. Within 21, is a coiled spring 27 fixed to the pulley at 28
and to a thimble 29, which surrounds the screw-threaded end of the shaft, and is
prevented from rotating by lugs 30 (Figure 11) entering a slot in the rear end of
the frame. The pulley 21 is closed by a cover-plate 31, having recesses 32 by
The nave 26 has a ball
which it is screwed into the outer face of the pulley.
bearing on the shaft. As the pulley is rotated by the rope 19, in the direction of
the arrow (Figure 7) the rear wheel is rotated when either of the driving levers 5
is depressed, by the foot of the rider pressing on the pedal, the pulley 17 draws the
rope 19 forward and the friction clutch rotates the rear wheel, thus driving the
bicycle. The pedals may be depressed either alternately or simultaneously, and
at such intervals as the rider desires, the extent of each stroke may be changed as
wished. A spring 33, having its one end attached to the pedal bearing and its
other end attached to the driving lever 5, raises the lever when the pressure of the
foot is released. To reduce the speed, the rider placing his foot upon the pin 18
brings the link 16 into the position shown in dotted lines in Figure 3, thus bring-
ing the pulley 17, much nearer to the fulcrum of the driving lever 5, and reducing
its range of motion accordingly. As additional means for adjusting the speed, a
set of holes 34 may be provided in the rear arm of the driving lever, so that the
link 16 may be pivotted in any one of these holes, and the link itself has holes 35,
in any one of which the pulley 17 may be pivotted. Instead of securing one end
of the rope 19 to the frame, as shewn in Figure 1, its return portion may be secured
to the cable itself, as shewn in Figure 11, thus halving the stroke of the friction
clutch.
Figures 12 and 13 shew other means of changing the speed, the pulley 171 being
pivotted on the rear arm of the lever 5¹ and the front end of the rope being secured
to a bell crank lever 36, the lower arm of which is normally held in place by a
sliding bolt 37 which is held in place by a spring 38. The rear end of the bolt
is bent upwards and terminates in a pawl 39, which engages the teeth of a ratchet-
wheel 40, having on its axis a lever 41 which is actuated by a cord 42, passing
The parts are normally in the
up to a point within easy reach of the rider.
position shewn in Figure 12, and when in this position the trigger 36 remains
stationary. When it is desired to reduce the speed, the rider pulling the cord 42
turns the ratchet wheel 40, and forcing back the belt 37 releases the trigger 36,
setting it free to follow the movement of the driving lever, as shewn in Figure 13,
thus reducing the speed one-half.
Figures 14 and 15 shew the invention applied to a machine having rotary cranks.
In these Figures, 51 is the crank axle mounted in ball-bearings in the hanger,
and to each end of this axle are secured crank arms 41 which have at their outer
ends pivots 71, upon which are mounted pulleys 111 preferably on ball bearings 12'.
To the outer end of the pivots 71 are secured pedal arms 81, carrying pedals 10¹.
Clutches 131 act upon the rear wheel as above described and ropes 14 extend
forwards from these clutches over the pulleys 11' and thence back to fixed
points 151 on the frame. With this construction, when the pedals are moved in
a rotary path in the ordinary manner, the clutches are alternately actuated so as
to drive the wheel. Moreover, the pedals may be rotated in either direction, or
may be oscillated, since any movement of them imparts motion to the rear wheel.
The front ends of the ropes may be secured to the ropes themselves instead of to
fixed points on the frame, so that the speed can be reduced as described in respect
of the first form of the mechanism.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is:-
1. Driving mechanism for a bicycle comprising a pair of pedal levers each carry-
ing a pulley operating by a rope or other flexible connection a spring friction

page_text: clutch on the nave of the rear wheel, substantially as described with reference
to Figures 1 to 11 inclusive.
2. In the driving mechanism above referred to, the arrangements for varying
speed substantially as described with reference to Figures 1, 3, 6 and 11.
3. The modified arrangement for varying speed substantially as described with
reference to Figures 12 and 13.
4. The modified driving mechanism comprising revolving pedal arms carrying
pulleys operating by a rope or other flexible connection a spring friction clutch
on the nave of the rear wheel substantially as described with reference to Figures 14
and 15.
.
1
1007
ABEL & IMRAY,
Agents for the Applicant.