An Improved Combination of Mechanism for Driving certain Bicycles and Tricycles.
Year: 1892

page_text: OM DIE DI FILIATION.
An Improved Combination of Mechanism for Driving certain
Bicycles and Tricycles.
We FREDERIC BENNETT LANGTON and STEPHEN BENNETT LANGTON both
of 313 Coldharbour Lane, Brixton in the County of Surrey Cycle Manufacturers
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 :-
This invention can only be applied to that class of bicycle and tricycle (commonly
called, in the case of bicycles, the "Safety" Bicycle) in which a cogged wheel
(known in our trade as a "gear wheel") secured upon the crank shaft drives a
smaller gear wheel secured upon the axis of the driving wheel (or driving wheel or
wheels in the case of tricycles) by means of an endless chain fitting the cogs upon
the peripheries of each of the gear wheels in the well known manner; and we
declare that the application of our invention is further limited to those machines
of this class in which the two cranks (which carry the pedals) and the gear
wheel upon the crank shaft are placed outside its bearings, as is now the more
general practice.
The advantage to the rider of what is called in our trade "narrow tread " is well-
known, and to effect it the distance between the crank axle bearings has been
narrowed, and as an additional, or as an alternative means various devices have
been employed for the purpose of connecting the gear wheel upon the crank shaft
to its adjacent crank so that they shall have but one "boss" or place of attachment
to the crank shaft instead of one each, and thus by economizing space in the
direction of the length of the crank shaft it can be shorter and the cranks with
their pedals (and consequently the feet of the rider) be brought closer together to
constitute a "
narrow tread." We object to the means of obtaining narrow tread
by narrowing the space between the bearings of the crank shaft because the strain
and friction and wear upon these bearings is greater when they are nearer together
instead of as far apart as practicable and we therefore limit ourselves to the method
of economizing space between the feet of the rider by connecting together
detachably or permanently or by originally making in one piece the gear wheel
and its adjacent crank, but always so that they shall have but one boss instead of
one each.
It has been found very desirable that the cyclist should be able (without the
necessity for resorting to a work-shop or a skilled mechanic) to quickly and easily
remove the circular gear wheel upon the crank shaft for the purposes of cleaning
and for simple repair and also so that he may replace it by another of larger or
smaller size so as to gain speed or power as he may desire under varying circum-
stances, and to this end the crank and its adjacent circular gear wheel upon the
crank shaft have been constructed in a variety of well-known ways so that the
circular gear wheel separately, and its adjacent crank separately, or the circular
gear wheel alone, or both together as one part could be readily so detached and 30
replaced by the cyclist. In cases where it has been desired to detach the circular
gear wheel without detaching the pedal crank one of the known ways has been to
construct the circular gear wheel without a boss or centre of any kind but it has
been provided with short arms or lugs upon the inner side of the rim for attachment
to corresponding arms or lugs projecting from the pedal crank. When this
attachment has been by means of screws or bolts and their nuts or other equivalent
letachable fastenings the gear wheel has (upon their detachment) been capable
(by reason of the large space in its central part) of being lifted around and off the

page_text: pedal crank without detaching the pedal crank from the crank shaft, especially
when the pedal has been first removed from the pedal crank.
An elliptic gear wheel is now in the course of coming into use (instead of the
circular one described) upon the crank shaft to drive the small circular gear wheel
upon the axis of the driving wheel of the machine. And it is found in practice
that this difference in the form of the two gear wheels upon the machine does not
involve such an amount of slackness in the endless chain as to constitute a serious
objection. The advantages obtained by this substitution of the elliptic form in the
larger gear wheel for the circular form are that by setting the pedal crank at or
about a right angle to the longest diameter of the adjacent gear wheel more speed
is obtained at the most useful part of the strokes of the feet and more power at
the less effective part of their strokes, which is when they are near to and are
'passing the dead points.
The object of our invention is to combine in the same machine the advantages
of narrow tread, detachability, and an elliptic gear wheel as herein described so
that they may all be enjoyed by the same rider at the same time, which has not
hitherto been done.
To this end we fasten the elliptic gear wheel described to its adjacent pedal
crank either by screws or by bolts and their nuts, (which may be unfastened by
the cyclist for the purpose of taking off the elliptic gear wheel without detaching
the pedal crank from the crank shaft as before stated) or by rivets or by soldering
or brazing or by any well known equivalent means, or we stamp or cast the
elliptic gear wheel and pedal crank originally in one piece, but in all cases so
that there shall be but one boss or part for attachment to the crank shaft. The
boss may belong to the pedal crank or to the elliptic gear wheel. We then attach
this boss to the crank shaft by means of a common tapered cotter pin and its nut
or by fitting the boss upon the squared or D shaped end of the crank shaft and
securing it by a nut upon the end of the crank shaft or by any other well known
equivalent means.
In the accompanying drawing the elliptic gear wheel is brazed to the pedal crank
and the whole is shown as capable of attachment to the crank shaft by means of a
common cotter pin and its nut.
We make no claim to a circular gear wheel upon the crank shaft as any part
of our improved combination either when fastened upon the crank shaft separately
or when fastened to it in conjunction with a pedal crank, nor do we claim any
single part of our improved combination when used alone, but having now
described the nature of our invention and the manner best known to us of
carrying it into effect we would have it understood that what we claim is :-
1. The combination of the elliptic gear wheel with its adjacent fixed or detachable
pedal crank (the combination having but one boss for attachment to the crank
shaft) in such a manner that the elliptic gear wheel can be detached from the pedal
crank and lifted around and off it without detaching the pedal crank from the
crank shaft as and for the purpose specified.
2. The combination of the elliptic gear wheel with its adjacent pedal crank
(the combination having but one hoss for attachment to the crank shaft) and with
a means of readily detaching the combination from the crank shaft as and for the
purpose specified.
Dated this 17th dow of Noah 1000