PROVEMENTS IN THE PROPELLING PARTS OF BICYCLES AND OTHER VEHICLES, PART OF WHICH IMPROVEMENTS ARE ALSO APPLICABLE TO OTHER PURPOSES."
Year: 1879

page_text: PROVISIONAL SPECIFICATION left by Thomas Mudd at the Office of the
Commissioners of Patents on the 14th August 1879.
"IM-
THOMAS MUDD, of Hartlepool, in the County of Durham, Engineer.
PROVEMENTS IN THE PROPELLING PARTS OF BICYCLES AND OTHER VEHICLES,
PART OF WHICH IMPROVEMENTS ARE ALSO APPLICABLE TO OTHER PURPOSES."
This Invention has reference to new or improved modes or means or arrangements
of mechanism for applying the power in driving bicyles and other vehicles, which
improved modes or means or arrangements of mechanism or modifications of the
same are also applicable to all positions or situations where power is given out
through a crank during one half of the revolution only and not during the other
half
This Invention further has reference to new or improved modes or means or
arrangements of mechanism for automatically altering the length of stroke of the
driving centre of the cranks of bicycles and other vehicles by the impetus of the
machine while running, and without necessitating dismounting or stoppage.
The nature and novelty of the first named portion of my said Invention consists
in mechanism so constructed that during that half of the revolution in which the
power is applied, the distance from the centre of the driven axle or shaft to the
centre of the driving crank, pin, or spindle is greater than during that half of the
revolution when the power is not applied. Thus whilst the leverage or distance
from the driven centre to the driving centre is reduced below half the full travel or
stroke of the driving centre during that half of the revolution when no power is
applied, and therefore when leverage is of no importance, the said leverage is
correspondingly increased beyond half the full travel during that half of the
revolution when the power is applied, and when therefore increased leverage is of
the most vital importance.
The nature and novelty of the last named portion of my said Invention consists
in mechanism so constructed that when the rider desires an alteration in the length
of stroke of the treadle spindle; he places his feet upon triggers provided for that
purpose, thereby causing such an alteration in position of the parts as to produce
the desired end; namely either a lengthening or a shortening of the travel or stroke
of the treadle spindle, crank pin, or driving centre, suitable to the nature of the
ground to be travelled over, or to other circumstances.

page_text: As applied to a velocipede I fix an eccentric sheave to the fork or other
framework of the machine, and it remains permanently in the position in which it
is fixed, the maximum benefit being attained when the sheave is fixed in such a
position that the centre line passing through the centres of the axle and that of the
eccentric is at right angles to the direction of the driving power.
On the eccentric
works an eccentric strap having a projection at one side through which is a long
slot. To reduce the friction between the strap and the sheave three or any greater
number of rollers are inserted. The rollers are preserved at permanent distances
apart from each other by means of a distance ring. The crank is firmly attached
to the axle. Through the crank is a long narrow hole or slot in which the runner
block is free to move. Through a hole in, the centre of the runner block passes the
crank pin or treadle spindle. Beyond the runner block the treadle spindle passes
through the slot in the projecting part of the eccentric strap and is firmly attached
to the said strap.
When power is applied to the treadle spindle or driving centre the whole
apparatus revolves except the sheave which remains stationary.
The slot in the projecting portion of the eccentric strap is for the purpose of
adjusting the total travel or stroke of the driving centre.
The above description explains one mode of carrying out my said Invention.
Numerous modifications might be made however if found desirable, producing the
same results. For instance, the crank might be a plain bar of round or square or
other section and passing through the treadle spindle.
Also the crank might be curved instead of straight.
Another mode of carrying out my said Invention is to entirely reverse the
position of the crank and place it with the eye of the crank working on the treadle
spindle, and the slotted part embracing a flattened projection on the end of the
axle. Or the crank may in this case also be a straight or curved rod of any section,
and pass through a hole or slot of similar shape in the end of the axle or shaft.
In this mode however of carrying out my Invention a much greater amount of power
is absorbed in friction than in the other modes. Another mode of carrying out my
said Invention is to constrain the treadle spindle to traverse a path of circular or
other form eccentric to the axle by causing it to traverse a fixed groove or cam of
the desired form, the groove or cam taking the place of the eccentric sheave and
strap.
And again another method is by means of a dead wheel fixed firmly to the fork
or other framework of the machine, and an idle wheel mounted on a stud attached
to the crank, which wheel is in gear with the dead wheel and also with a third wheel,
fixed to the pin which passes through a hole in crank, and to which pin a con-
tinuation piece of the crank is firmly fixed at the opposite side of the crank to the
wheel. A thin metal case would enclose the three wheels.
In applying this portion of my Invention to other purposes the arrangements of
the several parts are similar, or mere modifications of those already fully described.
In cases where the driven axle or shaft extends on both sides of the crank there
may either be a complete set of the gear on each side of the crank pin, each end of
the crank pin being fixed to one of the two excentric straps, the connecting rod or 4
other driver bearing on the centre of the crank pin in between the two excentric
straps; or there may be only one excentric sheave and strap, but two cranks, in
which case the crank pin is only attached at one end to an excentric strap, and the
other end which drives the opposite crank is free or overhung.
In the mechanism for automatically altering the stroke of treadle spindle of a 5
bicycle or other vehicle the crank radius is a mean between the maximum and
minimum radii which it is desired may be available, the treadle spindle is cranked
or excentric. The excentricity is equal to one half of the difference between the,
maximum and minimum radii of crank desired, and therefore equal to one quarter
of the difference between the maximum and minimum total length of stroke 5
desired.
The cranked párt has fixed to it a washer having four or any other number

page_text: of pins or arms projecting from it. The washer also has a flange in which there
are as many notches or gaps as there are pins, a spring is fixed to the crank at
that end nearest to the axle of the machine, and having at its other end a bent
part or pin which goes into a hole or notch in the body of the crank. The force
of the spring tends continually to keep the bent end or pin pressed hard into this
hole or notch in the body of the crank. The spring cannot however be in this
notch in the crank without at the same time being in one of the notches, and
therefore when the spring is down in its place the washer is firmly locked, and as
the part of the treadle spindle is firmly attached by a square or otherwise to the
washer, the treadle spindle also is firmly secured in the position in which it is placed,
and cannot turn on the centre either one way or the other, by a hook rivetted into
the spring and a trigger working in a tube. The rider effects alteration in the length
of stroke when he puts his toes on the trigger.
When attaching the excentric treadle spindle to my differential crank motion
herein before described, the slot in the projecting part of the eccentric strap, because
the eccentric treadle spindle effects the same end automatically while running,
whereas with the slot the adjustment can only be made by hand and when dis-
mounted. This combining of the two parts of my said Invention together also
enables a greater amount of eccentricity of the eccentric sheave of the differential
crank motion to be obtained than is possible when the adjustment of the stroke is
effected by the slot in the eccentric strap. The fixed end of the spring is attached
to a projection on the eccentric strap.