OPERATOR'S MANUAL

Preventive Maintenance Air System
Medium Duty
(R05/09) Y53-6027 – 197 –
Air System Function Test
Scheduled maintenance should be performed on the Medium
Duty vehicle’s air system, as outlined in the Medium Duty
Maintenance Manual and
Table 5. 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 lan-
yard. 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.
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 poten-
tially cause an accident involving death or injury.
Automatic Drain Valve
•
Safety Valve
•
Quick Release Valve
•
Manual Drain Valve
•
Table 5 Air System Scheduled Maintenance
MAXIMUM INTERVALS
TEST EACH WEEK
EACH MONTH
(10,000 mi) (16,000
km)
THREE MONTHS
(25,000 mi) (40,000
km)
SIX MONTHS
(50,000 mi) (80,000
km)
ANNUALLY
(100,000 mi)
(160,000 km)