Year: 1888

page_text: I, ALBERTUS PHILIPPUS KAPTEYN, of The Westinghouse Brake Company Limited,
Canal Road, Kings Cross, in the County of Middlesex, Engineer, 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 relates to improvements in the working of automatic air pressure
brakes such as the well known Westinghouse Brake which uses a valve apparatus
regulating the flow of air from a reservoir to the brake cylinder.
Such apparatus is so arranged that a certain reduction of pressure in the brake pipe
causes the triple valve to move downward so as to admit a corresponding quantity of
air from the reservoir into the brake cylinder and the brakes can thus be brought into
action with different degrees of force. On the other hand however when air is thus
admitted to the brake cylinder it is not possible to partially reduce the pressure.
Whenever an attempt is made to lessen the brake force, by increasing the air pressure
in the brake pipe, the triple valve moves upwards so as to exhaust all the air from the
brake cylinder, causing the entire release of the brake, whereas in some circumstances
it might be desirable to retain a portion of that air pressure.
According to my present invention I so arrange the valve apparatus that the partial
release of the air pressure in the brake cylinder can be effected thereby without in any
way decreasing the facility with which the said pressure can be increased for the
purpose of obtaining a greater brake power.
My invention consists mainly in the use in addition to the ordinary piston or
diaphragm that actuates the triple valve, of a supplemental piston or diaphragm of
smaller size which is connected by a loose or rigid connection to the other piston or
diaphragm and which is so arranged with its one side communicating with the brake
cylinder and the other side with the atmosphere, that on reducing the pressure in the
brake pipe, the main piston or diaphragm is lowered in the usual manner for causing
a valve or slide to open the communication between the brake cylinder and auxiliary
reservoir so as to admit air pressure to the former, but as at the same time such air

page_text: pressure in passing underneath the supplemental piston, causes this to rise and to move
upwards the main piston or diaphragm so as to close the admission valve again, so
soon as an equilibrium of pressure on both sides of the main piston is established. If
now the pressure in the brake pipe be slightly increased, the main piston or diaphragm
will be raised slightly higher thereby, and is thus made to open an escape valve
through which the pressure in the brake cylinder escapes to a certain extent, as how-
ever the pressure under the supplemental piston is reduced to a corresponding extent,
thereby also reducing the upward pressure exerted on the main piston, this will sink
again, allowing the escape valve to close and thus retaining a certain pressure in the
brake cylinder. On again slightly raising the pressure in the brake pipe the above
described operation is repeated and so on until the air pressure in the brake cylinder
is entirely exhausted; or by reducing the pressure in the brake pipe again the main
piston may be made to open the admission valve and thus increase the pressure in the
brake cylinder again if required.
The accompanying drawings shew a triple valve apparatus with diaphragm and lift
valve arrangement constructed according to my above described invention. Fig. 1
shews a vertical section on line XX Fig. 2; Fig. 2 shews a horizontal section on
line Y Y Fig. 1, and Fig. 3 shews a plan. A the main diaphragm and B is the
supplemental one. The space in the chamber F below the diaphragm communicates
with the brake pipe at E through a passage t, and the brake pipe also communicates
by passage m and check valve n with the auxiliary reservoir at H; the latter also
communicates with the space above the diaphragm A and through admission valve V
and passage o with the brake cylinder at G, which communicates by a passage r with
the space in the chamber of diaphragm B below the latter the space above the latter
being in communication with the atmosphere by a passage p. A separate stem C
passing in an air tight manner through the accurately bored hole in a bush D serves
to communicate the upward movement of B to A, the two diaphragms being otherwise
independent of each other in their motion although for the purpose in view they might
also be attached by means of a rigid connection.
The stem of the admission valve V is connected to the diaphragm A by a pin S
working in a slot, so that the diaphragm A can move up and down to a limited extent
independently of the valve, which is kept closed by a spring u that exercises also a
downward pressure upon A, but when A moves downwards beyond such limit it pulls
open the valve. In the passage o is formed a chamber containing a discharge valve K
closing an escape passage a leading to the outer air the valve being pressed down by
a spring and having a small stem passing down into the chamber F so that on the
diaphragm A moving upward beyond a certain point it forces open the valve.
2:
When a reduction of pressure is made in the brake pipe at E the diaphragm A
descends causing the pin to pull open valve V so as to admit air from the reservoir
at H through Fand o to the brake cylinder at G, and also through passage r to the
underside of diaphragm B; the latter being, thus lifted, will also push upward
diaphragm A so as to cause the valve V to close again when equilibrium is attained.
In order now to partially release the brakes, the pressure in the brake pipe is
slightly increased, whereby the diaphragm will be raised above its middle position
thus pushing open the exhaust valve K, and allowing some of the air pressure to
escape from the cylinder and also from under the diaphragm B. The lifting force of
the latter being thus decreased until the upward and downward pressure on A are
again in equilibrio, whereupon the springs on the valves K and V will force down
the diaphragm A to its middle position thus closing the exhaust and retaining a
certain air pressure in the cylinder for keeping on the brakes. On again increasing
the pressure in the brake pipe more or less the above operation may be repeated so as
either to still further reduce the brake pressure or to release the brakes altogether and
thus it will be seen that the degree to which brakes are released is as much under the
control of the driver as the degree to which they are applied.
It will be evident that my above described invention is equally applicable to other
known forms of triple valve apparatus, for automatic pressure as well as vacuum
belas

page_text: Having now particularly described and ascertained the nature of my said invention
and in what manner the same is to be performed, I declare that what I claim is :—
1. In triple valve apparatus for fluid pressure automatic brake mechanism, the use
in combination with the main piston or diaphragm of a supplemental piston or
diaphragm having its underside in communication with the brake cylinder and so
arranged that when the main diaphragm is raised for opening the escape valve and
reducing the air pressure in the cylinder, the pressure on the underside of the sup-
plemental piston or diaphragm is also reduced, thereby causing the main piston or
diaphragm to descend again and allow the escape valve to close so as to retain a
portion of the air pressure in the cylinder substantially as and for the purpose herein
described.
2. In triple valve apparatns such as is referred to in the preceding claim, the
combination with the main diaphragm A, having a slotted connection with the
admission valve V, of the supplemental diaphragm B connected by a loose stem C
with the diaphragm & and having its underside in communication with the brake
cylinder and with the escape valve K so that on the rising of the diaphragm A so as
to open the escape valve the upward pressure of the diaphragm B is reduced causing
the diaphragm A to descend again and allow the escape valve to close again, substan-
tially as herein described.
Dated this 3rd day of January 1888