Peterbilt Medium Duty Trucks Operator's Manual after 1-07

Air System
Air System Function Test
Scheduled maintenance should be performed on the Medium
Duty air system, as outlined in the Medium Duty Maintenance
Manual and Table 6. In addition, perform an Air System
Function Test at least every 3 months or if there is any
indication of a potential problem.
Air Tanks
The front (secondary) service tank is underneath the cab, on
the driver's side; the wet (supply) tank is underneath the front
service tank, behind the battery box; and the rear (primary)
service tank is attached to the left frame, just behind the cab.
The supply tank (or “wet” tank), must be drained on a daily
basis. Drain the supply tank by pulling the drain valve lanyard.
Hold it open until the escaping air is free of water.
The two service tanks (or “dry” tanks), must be drained on a
weekly basis. Drain the two service tanks by opening the
drain valves. Turn valve handles counter-clockwise, and
leave open until the escaping air is free of water.
Preventive Maintenance
WARNING! If the supply and service tanks are
not drained at the recommended frequency,
water could enter the air lines and valves. This
could cause corrosion or blockage, which could
compromise the brake system safety and potentially
cause an injury accident.
FRONT
SECONDARY
(SERVICE) TANK
Location of Air Tanks
DRAIN VALVE
REAR PRIMARY
(SERVICE) TANK
WET (SUPPLY)
TANK UNDER
FRONT SERVICE
TANK
02602
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.
– 162 – Y53-6008 Medium Duty (R10/06)