TM 9-2330-386-14&P
4-29 EMERGENCY RELAY VALVES ( CONT) .
C . Testing.
Connect air hoses to towing vehicle and charge semitrailer air system.
(1)
WARNING
T o prevent injury, keep hands away from brake chamber
push rods and slack adjusters. They will move as service
brakes are operated, and will automatically apply if
system pressure drops.
Have your assistant apply towing vehicle brakes and check that brakes of
(2)
all semitrailer wheels apply properly.
Have your assistant release towing vehicle brakes. Check that each
(3)
semitrailer brake releases promptly.
With brake system fully charged, close shutoff valve in emergency line on
(4)
t o w i n g vehicle. Disconnect air hose coupling tagged EMERGENCY. Make sure
semitrailer brakes apply automatically.
A p p l y soapy water to exhaust port (9)
(5)
on relay valve.
Leakage from exhaust port (9) must not
(6)
e x c e e d a one inch bubble in three
seconds. If excess leakage is seen,
C o n n e c t air hose coupling tagged
(7)
EMERGENCY. Open shutoff valve on
towing vehicle and check that
semitrailer brakes release
automatically.
Apply soapy water to fitting (2), hose
(8)
(4) ends, and pipe nipple (6). No
leakage is permitted. If leakage is
seen, tighten connection or replace
part.
R e m o v e wheel chocks and stow in brackets.
(9)
TASK ENDS HERE
4-54