Improvements in Drivers' Valves for Controlling Pneumatic Brakes in Railway Trains.
Year: 1889

page_text: Date of Application (in United Kingdom), 10th May, 1889
Complete Specification Left 10th May 1889-Accepted 20th July 1380
COMPLETE SPECIFICATION.
Improvements in Drivers' Valves for Controlling Pneumatic Brakes
in Railway Trains.
We, GEORGE WESTINGHOUSE Junior, and FRANK MOORE, both of Pittsburgh,
Pennsylvania, in the United States of America, Engineers, 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 :-
In pneumatic break apparatus known as the Westinghouse Brake for Railway
Trains, compressed air from a main reservoir on the locomotive is led along the train
by a train pipe coupled from carriage to carriage to supply auxiliary reservoirs, one
on each brake carriage. There is also on each brake carriage a cylinder and piston
or their equivalent with connections to the brake levers, and there are valves governing
the communications between the train pipe the auxiliary reservoir, the brake cylinder
and the open air so arranged that, when the train pipe is charged with compressed air,
it charges the auxiliary reservoirs but causes discharge of the brake cylinders taking
off the brakes, and when the pressure in the train pipe is reduced, compressed air
from the auxiliary reservoir is made to act in the brake cylinders, causing the brakes
to be put on with more or less force according as the pressure is more or less reduced
in the train pipe. For operating the brakes in this manner, the engine driver or.
other official has command of a valve, termed the drivers brake valve, by which he
can charge the train pipe with compressed air for taking and keeping off the brakes,
and by which he can discharge more or less air from the train pipe for putting
on the brakes with more or less force. It is to the construction of this valve that
the present invention relates as will be explained with reference to the accompanying
drawings.
Fig. 1 is a plan of the valve box with the cover removed to shew the valve seating
and its parts.
+
Fig. 2 is a section on the line XX of Fig. 1.
Fig. 3 is a section on the line Z Z of Fig. 1.
Fig. 4 is a plan of the rotating slide valve looking from above.
Fig. 5 is a plan of the same looking from below.
Fig. 6 is an elevation of the slide valve.
The valve casing is made in two parts 1 and 3 secured together by bolts and
nuts 29 with caoutchouc or other suitable packing 27 interposed between the flanges
to make a tight joint and to form a buffer for a piston 11 which works in a lined
cylindrical cavity in the part 3. The part 1 is covered by a cap 2 screwed into it,
and through this cap passes a spindle on which a handle 6 is secured by nuts. On
the spindle 5 is a disc 7 from the under side of which projects a wedge piece 8 which
fits into a corresponding recess in the upper face of a rotating slide valve 4, which
can be turned more or less round by means of the handle G. A packing washer 28 is
nterposed between the disc 7 and the cap 2 to prevent escape of air. On the
andle 6 is fixed a spring arm 9 which bears against the flange of the part 1. This.
Hange is shaped as shown in Fig. I so as to forin arrests for the spring arm 9 when

page_text: the handle 6 is moved into the various positions indicated by the dotted radial
lines A, B, C, D, M in Fig. 1. It forms a complete stop when the handle is in either
of its extreme positions A or M, and it forms a sensible resistance when the handle is
in any of the positions B, C or D. The valve casing 1 is connected by a branch F to
the main reservoir of compressed air and a chamber T in its middle is connected by a
branch 18 to a small reservoir; has also an escape outlet W¹.
In the parts 1 and 3 of the casing is formed a lateral passage V.making communi-
cation to a branch E which is connected to the train pipe. In this branch there is a
bent passage 22 forming an escape outlet, governed by a valve U at the end of the
stem 12 of the piston 11. At one side of the part 1 is a case 26 containing a valve 24
which is pressed to its seat by a spring 25 adjusted to sustain a predetermined
pressure The rotating slide valve 4 has through it a passage a and a hole b, and
in the under side of the valve is a large recess S, also a smaller recess a com-
municating with the passage a, and a curved recess s. The facing on which the
valve works has in it a port V leading to E, a port W leading to the outlet
with a lateral curved recess 9,-a port e leading to the valve 24, ports de and h
leading to the space T above the piston 11, it has also a recess or cavity a².
When the handle is in the position A, the port a of the valve 4 admits compressed
air to the recess a² of the seat thence by the recess S on the underside of the valve to
the passage V by which it passes to E, charging the train pipe, and thus causing the
brakes to be taken off and charging the auxiliary reservoirs throughout the train-At
the same time air passes by the port d to the space T above the piston 11 and thence
by the passage 18 to the small reservoir charging it with compressed air. In this
condition the piston 11 is subjected to equal pressure on each side of it and the valve U
remains closed.
When the valve 4 is partly turned by bringing the handle 6 to the position B, the
port of the valve coincides with the port c in the seating, allowing air to press
against the spring valve 24 and opening it to flow by a passage k to the passage V
and thence by the branch E to the train pipe. There is thus maintained in the train
pipe a pressure less than that in the main reservoir by the amount due to the
adjustment of the force of the spring 25 tending to close the valve 24. By this means
there is always maintained in the main reservoir a reserve of pressure exceeding that
in the train pipe, so as to ensure release of the brakes. Also in the position B of the
handle, which is its position while the train is running, the recess S in the underside
of the valve 4 still communicates with the train pipe E by the passage V, so that air
passes by the port d in the facing to the chamber T above the piston 11, thus
maintaining equilibrium of pressure on both sides of the piston, and charging the
small reservoir by the branch 18.
When the handle 6 is turned to the position D, the curved recess in the
underside of the valve 4 makes communication to the port e and by the curved
recess in the seating to the outlet port W. The pressure above the piston 11
being thus relieved, the piston is pressed upwards opening the valve U and thus
allowing air to escape from the train pipe E by the outlet 23. The pressure in
the train pipe being thus reduced, the brakes are put on with a force depending
on the extent to which the pressure in the train pipe is reduced, that is to say on
the time during which the handle is retained in the position D.
When the handle is moved to a position C intermediate between B and D the
valve 4 closes all ports but the discharge of air from the train pipe continues until
the pressure below the piston 11 becomes a little less than that above it in the
chamber T which is in communication with the small reservoir by the branch 18.
The piston 11 then slowly descends gradually closing the valve U until it stops
farther discharge by the outlet 23. The time occupied by the descent of the piston
to close the valve U is sufficient for equalising the pressure throughout the whole
length of the train pipe, thus ensuring uniform application of the break throughout a
long train.
When the handle is moved to the position M, the recess S in the underside of the
valve 4 makes free communication from V to the large outlet W and thus the pressure

page_text: in the train pipe is rapidly and largely reduced, causing the brakes to be put on with
great force and rapidity in the case of an emergency.
When after putting on the brakes, the handle is rapidly turned back to the
position A in order to take off the brakes, the train pipe might become so rapidly
charged as to produce excess of pressure under the piston 11 tending to raise the
piston unseating the valve U and allowing air to escape by the outlet 23. In order
to provide against this, the recess a¹ and port h, when the handle is in the position A.
form a communication to the space T above the piston 11, subjecting it to pressure
which prevents it from rising and opening the valve U.
Although a piston 11 has been described for acting on the valve U according as
the pressure on the one side of the piston is equal to or differs from that on its
other side, obviously a flexible diaphragm attached to the stem 12 of the valve U
might be substituted for the piston.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is
1. In pneumatic brake apparatus for railway trains, the construction and use of a
drivers valve for governing the supply and discharge of the train pipe by means of a
rotating slide valve moved by a handle to different positions, for putting on, main-
taining and taking off the brakes the said slide valve opening and closing suitable
ports and passages for compressed air and operating in combination with a piston or
diaphragm which automatically governs a discharge valve according as the
on the one side of the piston or diaphragm is made greater or less than the pressure
on the other side, substantially as described.
pressure
2. In a driver's valve such as is referred to in the preceding claim the combination
of a piston or diaphragm having a discharge valve on its stem, with ports or passages
which are governed by the rotating slide valve and which admit or discharge com
pressed air whereby the pressures on the two sides of the piston or diaphragm are
rendered equal or unequal and the discharge valve connected thereto is closed or
opened accordingly, substantially as described.
Dated this 10th dow of M... 1000
ABEL & IMRAY,
Agents for the Applicants.