TM 9-2330-271-14&P
EMERGENCY brake air hose coupling. Check whether
(2) Tighten any leaking connection.
semitrailer brakes apply automatically.
(3) Inspect for damage or corrosion.
(4) Connect EMERGENCY brake air hose to
(4) Replace reservoir if it leaks of if any
couplings. Open shutoff valve on towing vehicle and
damage or corrosion is found that would weaken
check for an automatic release of trailer brakes.
reservoir.
c. Leakage Test.
b. Removal.
(1) With brake air system of semitrailer
(1) Disconnect air hoses from towing vehicle.
connected and charged, apply soap and water solution to
(2) Open drain cock on air reservoir.
cover flanges which hold diaphragms and to SERVICE
(3) Disconnect air tube from relay valve to air
brake air hose coupling. No leaks should be present.
reservoir.
(2) If a leak is detected, tighten nuts on cover
(4) Remove four nuts, lock washers, and cap
flange and tighten coupling as required.
screws securing air reservoir mounting clamps to
(3) Coat exhaust port with soap and water
chassis, and remove air chamber.
c. Installation.
solution. Apply brakes and check for leaks.
(4) Release brakes and apply soap and water
(1) Position air reservoir with drain cock on
solution to exhaust port and check for leaks.
bottom.
(5) With relay valve in EMERGENCY position
(2) Secure air reservoir and clamps with four
cap screws, lock washers, and nuts to chassis.
and water solution and check for leaks.
(3) Connect air tube from relay valve to
(6) Leakage in tests (2), (3), and (4) above
reservoir.
must not exceed 1 inch bubble in 2 seconds. If excess
(4) Make leakage test (a above).
d. Drain Cock.
leakage is found, replace relay valve.
d. Removal.
(1) Leakage test. With air brake fully charged,
(1) Open drain cock on air reservoir.
test for leaks at drain cock using soap solution. Also
(2) Disconnect emergency and service air
check for leaks through the body by coating outside of
tubes, air reservoir air tube and brake air chamber air
drain cock with soap solution. Leakage in excess of a 3-
inch bubble in 3 seconds is not permissible. Leaks due
(3) Remove three cap screws and lock
to dirt can be corrected by cleaning and applying a coat
washers securing relay valve to mounting bracket and
of Artillery and Automotive Grease (GAA) on the key
remove valve.
before assembly. Leaks due to a damaged key or body
e. Installation.
require replacement of the drain cock.
(2) Removal. Open drain cock to release air
(1) Position relay valve on mounting bracket
from reservoir. Remove drain cock from air reservoir.
washers.
(2) Connect air brake chamber tubes, air
Inspect for damage or wear. Replace defective drain
reservoir tubes, and service and emergency air lines to
cock.
(3) Installation. When installing drain cock on
(3) Make operating and leakage tests (b and c
reservoir, apply sealer tape to pipe thread. Be careful
above).
not to bend the tapered key or to damage the body of the
drain cock.
4-42. Air Reservoir
4-43.
a.
Leakage Test.
(1) With brake system charged, coat drain cock
a.
Removal.
on air reservoir and outside of air reservoir with soap and
(1) Hold fitting stationary with a wrench and
water and check for air leaks. No leakage is permissible.
unscrew half-coupling.
(2) Pry packing ring out of body. Discard
packing ring.
4-48