PART 8: MAINTENANCE AND SERVICE
PB1319 (CAT. NO. 5296 ) —139— 22-01691 (R02/02)
The operation of the vehicle’s braking system and many vehicle
accessories depends upon the storage and application of a high-
pressure air supply.
Your vehicle’s compressor takes outside air and compresses it, usu-
ally to 100-120 psi. The compressed air then goes to the reservoirs
to be stored until needed. When you operate your air brakes, the
stored compressed air flows into the chambers where it is used to
apply your truck and trailer brakes. That is why, when you push down
on your brake pedal, you don’t feel the same amount of pressure on
the pedal that you do when you apply the brakes on your car. All you
are doing on your truck is opening an air valve to allow air to flow into
the brake chambers.
Air Supply System
Contamination of the air supply system is the major cause of prob-
lems in air-operated components such as brake valves, wiper motors,
and suspension height control valves. To keep contaminants to the
lowest possible level, follow these maintenance procedures.
Daily
• Drain moisture from the supply and service air tanks.
• Operate air devices to circulate lubricants within the unit.
Periodically
• Clean filter screens ahead of the valves by removing the screens
and soaking them in solvent. Blow them dry with pressurized air
before reinstalling them.
Twice a Year
• Add approximately 1/4 oz. (7.5 mL) of light viscosity lubricant to
the air line leading to the wiper motor. Acceptable lubricants are
Dow Corning 200 fluid, 200 CS viscosity, and Sprague Wiper
Lube. If you have alcohol dryers installed in the air system, the
alcohol can wash away lubricants from the wiper motors.
• Maintain the air compressor to prevent excessive oil by-pass. See
your shop manual for maintenance details.
• Replace worn seals in valves and air motors as they are needed.
WARNING! If the supply and service tanks are not drained
at the recommended frequency, water could be sent to all
air lines and valves. This could cause corrosion, which
could compromise the brake system safety and potentially
cause an accident.
CAUTION: Don’t use penetrating oil, brake fluid, or wax-
based oils in the air system. These fluids may cause
severe damage to air system components.
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