Brake drum temperature is cool to the touch after heavy braking operations have
SERVICE BRAKE ADJUSTMENT
Regardless of position of tractor's TRAILER AIR SUPPLY valve knob, the tractor
will NOT be able to supply air to semitrailer air tanks if the tractor's PARKING
BRAKE knob is pulled out (parking brakes set).
Brake adjustments must be done after the suspension assembly has been
completely reassembled and air pressure restored to the system or an improper
adjustment might be made.
Chock wheels on both tractor and semitrailer. Inside cab of tractor, push in both black knob for PARKING BRAKE
and red knob for TRAILER AIR SUPPLY.
Brake adjustments require that the semitrailer air tanks be fully charged to ensure
that each brake chamber push rod is fully retracted. With less than a fully charged
system, the brakes may release but not fully retract giving a false indication of the
caged position. If the brakes are not fully retracted, proper brake adjustment
cannot be completed.
Allow tractor air system pressure gage to reach 100 psi (689.5 kPa). Wait an additional 10 minutes to ensure that
semitrailer air system is fully charged and all brake chamber push rods are fully retracted.
Change 1 4-57