IMPROVEMENTS IN VELOCIPEDES
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by George Percival Smith at the Office
of the Commissioners of Patents on the 19th February 1883.
GEORGE PERCIVAL SMITH of Tunbridge Wells, in the county of Kent, Gentleman
"IMPROVEMENTS IN VELOCIPEDES
"
My invention relates to improvements in the mode of propelling velocipedes on
ordinary roads and of increasing the power of ascending hills: and relates also to
improvements in the construction of the frame and other parts and also in the
steerage of these vehicles.
It is well known that in the ordinary velocipede, the power of the rider is less
at the commencement of the foot stroke than towards the end, for two reasons.
First, the position of the leg which then being much bent at the knee has not so
much power as when by the descent of the foot it becomes straighter, and secondly
from the position of the [crank which at the commencement of the stroke has
comparatively small power. The first part of my improvements consists in
providing greater leverage at the commencement of the stroke for directly rotating
the axle which leverage decreases during the stroke as the power of the rider
increases and this part of my invention therefore is well adapted to the varying
power of the rider and the requirements of the vehicle.
A suitable arrangement for carrying out this part of my invention consists as
follows:-
The two driving wheels are connected with a through axle in such a way that
when it rotates in the proper direction the wheels rotate with it thus carrying the
vehicle forward. With the axle, at right angles to it and at equal distances from
the middle, two discs are fitted by means of a connection which allows them to
rotate the axle when revolving in one direction and disengages them from it when
this motion is reversed. Round each disc a cord or band is wound one end of
which is attached to the disc and the other to a stirrup or pedal on which the
rider's foot rests. The foot being thrust down turns round through a certain angle
the disc, on whose periphery the band acts tangentially thus producing a corre-
sponding rotation of the axis and driving wheel. The same movement causes, by
a certain arrangement of levers or pullies the other disc to retrograde and raise the
stirrup or pedal of the other foot which thus is ready in its turn for the next
stroke and by their alternate actions a continuous motion of the vehicle is
maintained.
These discs are not circular and in the peculiar forms of their peripheries my
improvements so far as this mode of effecting the hereinbefore described object is

page_text: concerned consists. Their form is such that the distances from the centre of the
axle from successive points in their periphery, i.e. their radii, increase, these points
being taken in the direction of that end of the band attached to the stirrup or
pedal. When the stroke commences it acts therefore on the periphery of the disc
at a point where the tangential force is greater than at subsequent and successive
points, where it gradually decreases, thus accomplishing the effect I have described.
As the discs can be constructed so that their radii increase through the whole or
greater part of an angle of three hundred and sixty degrees and as less than half
the periphery of each disc is used for one stroke, it follows that one portion of the
disc, viz, that containing the smaller radii may be used for propelling the tricycle
on ordinary roads, and the other portion containing the larger radii will be
available for impelling the tricycle with increased power on hilly or heavy roads
and the use of this means of increasing the power constitutes another part of my
invention by which increased power is thus provided embodying also the
fundamental differential principle.
I effect this use of different portions of the disc in various ways among others
by turning the disc round for a certain angle and thus presenting to the tangential
action of the band, portions containing longer or shorter radii as required, or I
divide the disc into two parts, viz, a circular disc and a surrounding annulus of
unequal width, which by means of concentric adjustment of the annulus as regards
the circular portion offers to the tangential action of the band, a series of longer or
shorter radii. I also use a portion only of the undivided disc both for level and
hilly roads and increase the power for hill climbing by adjustment in the pedals
which gives increased power.
Although I have described the use of discs of varying radii as a means of
effecting the desired variation of leverage I do not confine myself to this particular
method of carrying out the principle of this part of my invention.
For the purpose of steerage I continue the backbone in a somewhat horizontal
direction towards the axle-of-the steering-wheel-terminating it in a horizontal_
fork within which the wheel runs. This fork is connected with the backbone by
a horizontal hinge and a short arm is at this hinge attached to the fork by which
as a lever the wheel steers the vehicle by the usual means. The advantages are,
dispensing with a portion of the back bone thus saving weight, diminution of
vibration by avoiding the angle usually of ninety degrees made by the backbone
with the fork and also a saving of room for stowage of the velocipede as the
vehicle may be shortened by more than the diameter of the steering wheel by
turning it back at the horizontal hinge.
I make an improvement in the connection of the handle of a bicycle with the
steerage apparatus which is advantageous inasmuch as it allows the fork of the
driving wheel to be at certain times rigidly fixed to the backbone by which
construction the direction of the driving wheel is at such times unaffected by the
action of the feet upon the crank.
This I effect as follows:-
I cause the fork of the driving wheel to be attached to the backbone by means
of a connection which effects immediate liberation for steerage at the will of the
rider, while at other times the fork is rigidly fixed to the backbone so as to avoid
being affected by the thrust of the foot on the crank.
In the place of and to effect the same result as a common, ratchet and pawl
and for double driving and other purposes I propose to have three, four or more
pawls of different lengths so that one of them shall always be at hand to engage
quickly with a tooth of the ratchet by which means the speed with which the pawl
engages with the ratchet is increased