IMPROVEMENTS IN APPARATUS FOR WORKING RAILWAY BRAKES
Year: 1878

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PROVISIONAL SPECIFICATION left by Richard David Sanders at the Office
of the Commissioners of Patents on the 22nd April 1878.
RICHARD DAVID SANDERS, of Birmingham, in the County of Warwick, Mechanical
Engineer. "IMPROVEMENTS IN APPARATUS FOR WORKING RAILWAY BRAKES."
My Invention consists in apparatus constructed as herein-after described, to be
used for working railway brakes by vacuum, compressed air, or other fluid pressure.
The first part of my said Invention consists in the use of a single flexible
diaphragm, which divides a chamber into two parts, a constant vacuum or pressure
being maintained on both sides of the said diaphragm during the time it is not
required to operate upon the brakes. A piston in a cylinder may be used instead of
a diaphragm and chamber.. When equal pressure is on both sides of the diaphragm
or piston the said diaphragm or piston is maintained at one end of its stroke by a
spring or weight, or other means. In this position of the diaphragm or piston the
brakes are
"off" or out of action. When it is required to put the brakes into action
one side of the diaphragm or piston is relieved from exhaustion or pressure, and the
vacuum or pressure remaining on the other side of it forces the said diaphragm or
piston in the direction opposite to that last referred to, and applies the brake to
which it is connected by suitable mechanism.
In order to release the brakes, and to put the diaphragm or piston into its normal
position, the two sides of the diaphragm are put into equilibrium.
My Invention consists, further, in apparatus to be used for regulating the flow of
vacuum or pressure to and from the sides of the diaphragm or piston herein-before
described.
In a cylinder or chamber is a piston or valve, which is operated upon by the
vacuum or pressure in the continuous pipe on the railway train in such a manner
that when a reduction of pressure takes place in the said continuous pipe one side
of the diaphragm or piston is relieved from pressure and the brakes are applied as
before described.
When it is required to take the brakes out of action the vacuum or pressure in
the continuous pipe on the train is restored and the sides of the diaphragm or
piston are put into communication with each other.

page_text: Although the apparatus described for putting the two sides of the diaphragm or
piston into equilibrium and for relieving the pressure on one side answers the
purpose, yet other analogous apparatus may be employed.
The same apparatus may be used where two diaphragms or pistons are used to
operate the brakes.
The diaphragm or piston may be made to operate upon the brakes by a simple
valve in the diaphragm for preserving the vacuum or pressure on one side when it
is relieved on the other in the same way as the valve described and illustrated in
the Specification of Letters Patent granted to me on the 5th day of July 1875,
No. 2425.
A small hole may also be made in the diaphragm or through the valve by which
the pressures on both sides of the diaphragm are equalized for taking the brakes
out of action. When the brakes are in action the vacuum or pressure is only
maintained for a limited time.-
The action of the diaphragm with a hole through it resembles the action of the
piston used for signalling on railway trains, described and illustrated in the
Specification of Letters Patent granted to me on the 30th day of April 1874,
No. 1522.
The vacuum or pressure may be regulated in or out of the chamber or cylinder
containing the diaphragm or piston by two lines of pipes throughout the railway
train; that is to say, the vacuum or pressure may be relieved from the diaphragm
or piston by one set of pipes and admitted by the other set. In place of self-acting
valves or pipes other mechanical means may be employed for regulating the vacuum
or flow of air into and from the said diaphragm or piston; for example, a cock or
valve may be used to effect the same object.
The apparatus constituting the essential part of my present Invention consists of
a single diaphragm or piston in a chamber or cylinder constructed and operating as
before described directly upon the brake gearing, or used to act upon intermediate
mechanism, by which the brakes are put into operation.
Various means may be employed for maintaining the vacuum or pressure in the
continuous pipe or pipes on the train.