(4) Apply a 9/16 wrench to worm shaft hex head (3).
Push in against slack
adjuster (2) to unlock worm shaft.
(5) Turn hex head of worm shaft (3) clockwise on slack adjuster (2) until wheel
cannot be turned.
(6) Back off the worm shaft until wheel turns freely.
(7) Repeat steps 1 through 6 for other slack adjusters, as necessary.
(8) Lower jack and remove from axle.
Emerqency Relay Valve, Drainaqe of Moisture and Tests.
(1) Operating tests.
(a) With air hose couplings connected to towing vehicle, apply brakes.
that brakes of all semitrailer wheels apply properly.
(b) Release brakes.
Check that each brake releases promptly.
(c) With brake system fully charged, close shutoff cock in emergency line on
towing vehicle. Disconnect air hose coupling tagged EMERGENCY. Make
sure semitrailer brakes apply automatically.
(d) Connect air hose coupling tagged EMERGENCY. Open shutoff cock on towing
vehicle. Check that brakes release automatically.
(2) Leakage tests.
(a) With air brake system connected, apply soapy water to spring brake
chamber flanges that hold diaphragm and to service air line coupling. No
leakage is permitted. Tighten nuts on flanges and tighten coupling as
(b) With emergency relay valve in emergency position (see lC above), coat
(c) Leakage tests must not exceed a one inch bubble in three seconds. If
excess leakage is found, replace emergency relay valve.
Multi-Function Valve Tests.
Wear protective goggles when opening the air reservoir
drain cock. Avoid contact with the air stream.
Failure to observe this warning could result in
serious personal injury.
(1) Charge semitrailer air system. The spring brake chambers should release.
Shut off the engine, leaving the ignition on and open the drain cock on the
front or rear air reservoir. Coat drain cock with soapy water.