AN IMPROVED PNEUMATIC RAILWAY BRAKE
Year: 1875

page_text: PROVISIONAL SPECIFICATION left by William Harley White at the
Office of the Commissioners of Patents, with his Petition, on the
18th May 1875.
I, WILLIAM HARLEY WHITE, of Edinburgh, in the County of
Mid Lothian, North Britain, Olerk, do hereby declare the nature of the
said Invention of "AN IMPROVED PNEUMATIC RAILWAY BRAKE,” to be as
follows, that is to say :-
This Invention which relates to an improved pneumatic railway brake,
hasfor its objects, efficiency, readiness of application, simplicity, and cheap-
ness. It consists in attaching to the under side of the tender at a convenient
distance from its front end a compressing cylinder or barrel, whereof the
piston rod is connected by an intermediate connecting rod to a crank
formed on a shaft extending transversely across the under side of the
tender and near to the leading axle, and having keyed thereon a spur or
toothed wheel. Upon the leading axle of the tender is also keyed a spur
or toothed wheel, and is opposite to that on the crank shaft. Between
the crank shaft and the axle is a transverse rod or shaft capable of being
moved transversely, and having a pinion thereon, which, by a lever, is

page_text: thrown into or out of gear with the aforesaid spur or toothed wheels,
with both of which it gears simultaneously. The compressing cylinder
communicates with a second cylinder or receiver of larger dimensions
in which is placed a piston, between which and the end of the large
cylinder furthest from the compressing cylinder or barrel are placed
spiral springs, tending always to keep the piston from that end. The
piston rod attached thereto is forked at its outer extremity, and carries
a small pulley or antifriction roller, over which is passed a chain or other
similar connection, one end of which is attached to the cylinder, and the
other after passing round a roller or pulley attached to the lower side
of the cylinder is coupled to rods carried in brackets, in which they are
free to slide longitudinally along the inside of the side soles of the
carriages. These rods are furnished at proper places with brackets
depending therefrom, and carrying rollers which rest upon jointed
inclined rods or bars pivoted on the axles of the carriage wheels, and
having their apex extending midway between two pairs of wheels. A
flat spring tends to keep them in their normal position, and the brake
shoes are attached to them towards their lower ends.
When it is desired to put down the brakes the pinion aforesaid is
caused to gear with the spurs and the crank to revolve. Compression of
air at once takes place in the cylinders, and the piston in the larger
cylinder or receiver is driven towards the end thereof, thus exerting a
. strain on the chain and rods carrying the rollers and producing a
downward pressure on the inclined rods or bars and forcing the brake
shoes against the wheels.
On the brakes being released the compressed air escapes from the
large cylinder into the atmosphere by means of a valvo which is worked
by a lever from the engine or tender. The piston is forced by the spiral
springs into its normal position, and air passes into the smaller cylinder
or barrel through a valve in its under side, the vacuum produced therein 8
permitting the air to force it open.