Improvements in Release Valves for Pneumatic Brakes.
Year: 1892

page_text: COMPLETE SPECIFICATION.
[Communicated from abroad by CHARLES GOODWIN EMERY, of New York City,
New York, in the United States of America, Manufacturer.]
Improvements in Release Valves for Pneumatic Brakes.
1, OLIVER IMRAY, of No. 28 Southampton Buildings, Chancery Lane, in the
County of London, Chartered Patent Agent, 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 the release valves employed in pneumatic brakes for
reducing the pressure at one side of a brake piston so as to put on the brakes
gradually as at stations, or suddenly in case of emergency. I shall describe the
construction and arrangement of valve and its connections according to my invention
referring to the accompanying drawings.
Fig. 1 is a general plan shewing the connections of the release valve to the train
pipe and brake cylinder.
Fig. 2 is a longitudinal central section of the brake cylinder.
Fig. 3 is a vertical section of the release valve connecting the brake cylinder
with the train pipe.
Fig. 4 is an end view of the same, partly in section and
Fig. 5 is a similar view showing a modification.
1 is a brake cylinder having its one end 2, with a central orifice 3 and its other
end 4, with stuffing box 5, through which passes the rod 6, connecting the piston 7
with the brake actuating levers in any known manner.
The piston 7 separates the cylinder 8, in which it works from the air tight
reservoir 9, and has a central passage 10 in which are two valve seats 12 and 13 for
a spherical valve 14. The valve seat 13 is made with slots 15, so that when the
valve rests against it, air can pass into the reservoir 9 but air cannot return from 9
to 8 owing to the valve seating on 12 and operating as a check valve. A retractile
spring 16 of considerable power surrounds the rod 6, this spring being secured at
one end to the cylinder head 4, and at the other end to the piston 7 and tending to
draw the piston in a direction to release the brakes and compress the air contained
in the reservoir 9.
The orifice 3 being connected with the train pipe, when the pressure in the train
pipe is raised air flows into the cylinder 8, and through the passage 10, into the
reservoir 9, at the same time aiding the spring 16 in forcing the piston 7 forwards
for releasing the brakes.
Owing to the strain of the spring on the piston the air in the reservoir 9 has a
pressure somewhat in excess of that in the cylinder 8, the valve 14 being thus held
against the seat 12.
The orifice 3 does not connect directly with the train pipe 21 but connects by a
pipe 17 with the release valve shewn in Figs. 3 and 4. The casing 18 has at one
side a screw socket 19, connected as at 20, with the train pipe 21, and at the other
side a detachable flange coupling 22 of the pipe 17 which holds in position a
skeleton frame 23. In this frame is a central sleeve 24 in which can slide the valve
stem 25, having a small hole 26 extending through it. From the lower part 27 of
the valve casing a passage 29 leads to an outlet port 28 provided with flap valves 43
which open to allow escape of air but close against entrance of air into the valve
casing.
31 is a slide valve having through it a passage 30. The valve stem 25 has a face
plate 32 which is pressed against one side of the valve 31 by a spring 33, but, when

page_text: the pressure is restored in the train pipe, the air passing through the port 30, moves
the face plate 32 away thus fully opening supply to the cylinder 8 and causing quick
release of the brakes.
The slide valve 31 has a recess in its upper part in which loosely engages the
shouldered head 34 of the valve stem 35 through which extends a longitudinal
channel 36. The recess connects by a port 37 with the valve chamber 27 so that
air can flow by the channel 36 into an air chamber 38 formed in the upper part of
the valve casing above a moveable diaphragm 39, which, as shewn in Fig. 3 is a
disc of flexible material clamped at its periphery to the valve casing by a
chambered head 40, or which may be a piston as shewn in Fig. 5.
A spring 41 presses the diaphragm or piston upwards raising the head 34 from
the port 37 which is thus opened.
When the driver's valve 42 is in position to retain the pressure in the train pipe,
in the valve casing and in the brake cylinder, the pressure beneath the diaphragm
or piston 39 equals the pressure in the chamber 38 above it but the diaphragm or
piston is kept up by the spring 41.
When the pressure is raised in the train pipe 21 air flows through the port 30,
of the slide valve 31 (pressing the valve 25 away) and passes into the cylinder 8,
causing the piston 7 to advance releasing the brakes. When the pressure in the
train pipe is slowly reduced by the valve 42 for the gradual application of the
brakes, as in stopping at a station, air flows from the cylinder 8, through the small
passage 26 and port 30, to the train pipe; the spring 41 still holds up the diaphragm
or piston 39 so that some of the air can escape from the chamber 38 through the
channel 36 and port 37, so that there is not sufficient pressure above 39 to move
down the slide valve 31 and close the port 30. But if the brakes are to be applied
suddenly, as in an emergency, the valve 42 is moved so as rapidly to release the
pressure in the train pipe, whereupon the pressure in the chamber 38 depresses the
diaphragm or piston 39, in opposition to the spring 41, thus moves down the head 34,
to close the port 37, and pushes the slide valve 31 down into such position that its
port 30 is in line with the channel 29 and consequently air escapes through the air
outlet 28.
Thus pressure in the cylinder 8 is suddenly released and consequently the piston 7
is forced back by the pressure in the reservoir 9, causing the brakes to be instantly
applied.
Obviously, in this manner will occur sudden application of the brakes if the
train pipe is ruptured or accidentally uncoupled so as to allow immediate escape of
air from the train pipe.
Although I have described the valve stem 35 as being moveable to a limited
extent for closing the port 37, this is not necessary as the chamber 38 may remain
in continuous communication with the valve chamber 27, by a passage so small that
sufficient pressure is maintained in the air chamber 38.
The engineer's valve 42 may be of any construction suitable for charging the
train pipe and slowly or rapidly releasing the pressure in the train pipe.
The brake cylinder is provided with a cock or valve 44 for discharging
compressed air from the reservoir 9.
The release valve according to my invention may obviously be employed in
connection with a brake cylinder differing in structural detail from that described
and shewn in the drawings.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. In combination with the brake cylinder, train pipe and driver's valve, of a
pneumatic brake, a release valve interposed between the train pipe and the brake
cylinder and having a slide valve subject to the pressure of a spring in the one
direction and to air
direction, this slide vapressure on a flexible diaphragm or piston in the opposite
governing ports communicating with the external air and

page_text: with the train pipe and by a large or small channel with the brake cylinder,
substantially as and for the purposes set forth.
2. In a release valve for pneumatic brakes, an automatically operating slide
valve governing ports of different area, the smaller allowing slow release of
pressure
in order to gradually apply the brakes, and the larger allowing rapid release of
pressure to suddenly apply the brakes, substantially as described.
3. In a release valve for pneumatic brakes, a casing having an outlet to the
external atmosphere, a diaphragm or piston to provide a pressure chamber, a slide
valve having ports, a valve stem having a longitudinal channel, and a spring yielding
valve plug having a reduced channel and seating against one side of the slide valve,
substantially as described.
Dated this 5th day of January 1891.
ABEL & IMRAY,
Agents for the Applicant.