TM 55-203
it from the triple valve. The wasp excluder (if used)
in figure 8-50. The resulting movement of the slide
should be removed from the retaining valve during the
valve opens port t In the slide valve seat and allows air
usual brake cleaning period and the retaining valve pipe
from the auxiliary reservoir to flow to the top of
blown out, after which the wasp excluder should be
emergency piston 8, forcing the latter downward and
replaced in the retaining valve.
opening emergency valve 10.
c. Brake Cylinder Lubrication.
The pressure in chamber Y being thereby instantly
relieved, allows brake pipe air to raise the check valve
15 and flow rapidly through the chambers Y and X to the
(1) Disassembly.
Close the branch pipe
brake cylinder, until brake cylinder and brake pipe
cutout cock and drain the auxiliary reservoir. Fasten the
pressures nearly equalize, when the valve is forced to
hollow piston rod and nonpressure head together with a
its seat by the check valve spring, preventing the
cotter pin through the hole provided in the hollow rod or
pressure in the cylinders from escaping back into the
with a suitable clamp.
Remove -the nuts from
brake pipe again. The emergency valve, being held
nonpressure head bolts, then remove the piston from
open by the emergency piston, will consequently return
the cylinder.
to its seat when the auxiliary reservoir and brake
cylinder pressure have nearly equalized. At the same
(2) Cleaning cylinders.
Scrape the old
time, port s in the slide valve registers with port r in the
lubricant from the cylinder wall and leakage groove and
slide valve seat and allows air from the auxiliary
wipe these surfaces clean and dry. Kerosene may be
reservoir to flow to the brake cylinder. But the size of
used for assisting in cylinder cleaning but should be
ports s and r is such that comparatively little air gets
completely removed to prevent damage to cylinder
through them before the brake pipe has stopped venting
gaskets and packing cups. If the cylinder wall is rusted,
air into the brake cylinder. This sudden discharge of
the rust should be removed with sandpaper.
brake pipe air into the brake cylinder has the same
effect on the next triple valve as would be caused by a
(3) Cleaning piston and packing cup.
similar discharge of brake pipe air to the atmosphere. In
Remove expander ring (if used) from piston Scrape old
this way ,each triple valve causes the next to assume
lubricant from the metal part and packing cup, using a
emergency position, thus giving a quick and full
dull-edge round-end scraper (like a case knife), and
application of all brakes.
wipe all surfaces clean and dry. The packing cup should
be carefully examined and should be renewed if brittle,
The release after an emergency is effected in exactly
thin at any point, cut, cracked, or otherwise defective.
the same manner as after a service application, but
Examine piston and follower plate for cracks and tighten
requires longer time, owing to the high brake cylinder
up follower plate nuts.
and auxiliary pressures and lower brake pipe pressures.
(4) Applying new packing cups. Examine
8-24. Maintenance
follower studs for tightness in the piston. Locate the
packing cup centrally on the piston. Place the follower
in position and apply the nuts, bringing them in contact
a. General. The movable parts of the triple valve
with the follower without tightening. Then draw them
should never be removed while it is on the car. If the
down uniformly.
valve is not working properly or needs cleaning and
oiling, take it down and replace it by a valve in good
(5) Application of lubricant. Apply a coating
condition. All cleaning and oiling should be done at a
of brake cylinder lubricant to the wall of the cylinder and
bench, by a competent mechanic, where the liability of
to the outside of the packing cup with a brush.
damage to the internal parts of the valve is least. Any
attempt to take the triple valve apart while still on the
(6) Assembling. The piston should be stood
car is almost sure to result in a large percentage of
valves being injured by careless handling or dirt getting
on end with the top edge or flat side of the nonpressure
inside the pipes or valve. If repairs are necessary, such
head flange and the opening of the expander ring (if
triple valves should be returned to the shops for that
used) toward the workman. With the piston In this
purpose.
position, enter it into the cylinder. The sleeve or rod
should then be slowly raised and the piston moved into
b. Retaining Valve. The retaining valve should
the cylinder until the upper portion of the packing cup
engages
stand vertically; there should be no obstruction to the
removal of the caps; it should be so located as to be
freely accessible when the train is in motion. It should
be cleaned, but not oiled, every time the remainder of
the airbrake equipment receives that attention; both it
and the connecting pipe should be well secured; and a
little flexibility should be provided in the pipe leading to
8-54
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