Improved Ratchet Gear for the Chain Wheels of Bicycles and other Velocipedes.
Year: 1898

page_text: Date of Application, 19th Sept., 1898-Accepted, 17th June, 1899
COMPLETE SPECIFICATION.
Improved Ratchet Gear for the Chain Wheels of Bicycles and other
Velocipedes.
I, FREDERICK EDWARD BLACKETT BEAUMONT, of St. Margarets Mansions,
51, Victoria Street, Westminster, in the County of London, Colonel, do hereby
declare the nature of this invention and what manner the same is to be performed
to be particularly described and ascertained in and by the following statement:--
My invention relates to an improved construction of ratchet gear for connecting
the chain wheel of chain driving gear to the driving road wheel so that the chain
wheel and consequently the driving cranks can remain stationary while the driving
road wheel continues to run forward in going down hill or by impetus.
My invention has for its object to obtain a very strong and reliable construction
of ratchet, which at the same time occupies a minimum of space, so that the ratchet
gear can be applied without, to any material extent, altering the existing con-
structions of driving wheels and their chain gear.
I will describe the invention with reference to the accompanying drawing in
which Fig. 1 shews a side view of the complete chain wheel and ratchet device,
Fig. 2 shews a side view with the cover plate removed, Fig. 3 shews a vertical
section, Fig. 4a detached plan of the central disc with its pawls, and Fig. 5 a
detached side and end view of one of the pawls to an enlarged scale.
Figs. 6 and 7 shew part front view and section of a modified construction.
A disc A having a screw threaded boss A¹ for screwing on to the hub or axle of the
driving wheel, has two diametrically opposite notches a a and fits accurately
within the internal periphery of an annular disc B which constitutes the chain
wheel, and the inner part of which corresponds in thickness to that of the disc A.
In the internal periphery of B are formed four or more notches b, and into the
notches a are fitted loose blocks C serving as pawls, being arranged to abut with
their slightly rounded rear end against the one side of the notch a of disc A, and
with their tooth like front end against the radial face of the notch, 6 of the chain
wheel B the pawl being pressed outward for effecting such engagement by a small
blade spring or wire 1) contained in a groove cut in the periphery of the disc A
as shewn at Fig. 4. In this relative position of A and B shewn at Fig. 1, the
chain wheel B on being rotated in the direction of the arrow by the cranks and
chain gear, will effect the rotation of the disc A and consequently of the driving
wheel, while if the chain wheel be held stationary while the driving wheel and
disc A continue to revolve in the same direction, the pawls C will be pressed down
into the notches a, against the action of the springs D, by the inner periphery
of the chain wheel, as shewn at Fig. 2.
The above described parts are secured in the described relative positions by two
annular cover plates E E, which are fixed by screws F against each side of the
inner part of the wheel B, and fit without pressure against the sides of A while
their central holes fit accurately upon the turned outer surface of the boss A¹, so
that when the part A is revolving within the stationary wheel B, it runs both
on the inner periphery of B and on the inner peripheries of the two plates E thus
affording a sufficient bearing surface to prevent material wear, the parts are at the

page_text: same time strongly held together notwithstanding the narrowness of the con-
struction.
The pawls C are preferably hollowed out on the undersurface, as shewn, for
insuring the correct position of the springs D. The pawls may also be made to
fit with a slightly rounded rear end face into a corresponding hollowed abutment
face of the disc A.
In the modification shewn at Figs. 6 and 7 the above described arrangement
is reversed, that is to say, the pawls C are contained in notches in the inner part
of wheel B, and engage with ratchet notches in the disc A, being pressed into
engagement by wire springs D.
In this case the pawls may either be loose blocks as before, or they may be
carried on pivot pins d, carried in holes in the cover plates E as shown.
It will be seen that by the above described construction an effective ratchet
coupling is provided for the chain wheel, while retaining this of practically the
same width as the ordinary fixed chain wheels, and consequently no alteration of
the existing frames and driving wheels is required for applying my invention to
bicycles of present construction.
Having now particularly described and ascertained the nature of this
invention and in what manner the same is to be performed, I declare that what
I claim is:-
1. Ratchet gear for the chain wheels of bicycles and other velocipedes consist-
ing of the combination of a disc A with boss A¹ adapted to be fixed to the hub or
axle of the driving road wheel and fitting within a central opening in the chain
wheel B, blocks C constituting pawls fitting into notches a in the disc A and
adapted to take into notches b in the inner periphery of the wheel B, springs D
fixed to the disc A and pressing the pawls into engagement with said notches b
and annular cover plates E fixed to each side of the wheels and bearing with their
central openings upon the periphery of the boss A' substantially as described with
reference to Figs. 1 to 5 of the drawings.
2. The modified arrangement of the ratchet gear referred to in the first claim,
wherein the pawls C and springs D) are carried by the chain wheel B, while the
periphery of the disc A is formed with ratchet notches for engagement with the
pawls, substantially as described with reference to Figs. 6 and 7 of the drawings
Dated this 19th day of September 1898.
ABEL & IMKAI,
Agents for the Applicant.