TRUCK SERVICE MANUAL
BRAKES-AIR
Fig . 3 . Sectional View of AD-1 Air
Fig. 4. Sectional View of AD-2 Air Dryer
Dryer
a lock (retaining) ring, capscrews and retainers, and
houses the purge valve and heater assembly if so
equipped.
The heater and thermostat assembly prevent freeze-
up in the purge drain valve when the dryer is used in
severe winter conditions. The heater and thermostat
assembly is standard in the AD-2 and was optional
equipment for the AD-1. The 60 watt, 12 or 24 volt DC
heater and thermostat assembly has an operating range
between 100 C and 320 C (500 F and 850 F).
OPERATION
The operation of the air dryer can , best be described
by separating the operation into two cycles; the charge
cycle and the purge cycle.
Charge Cycle (Fig. 5)
With the compressor in its "loaded" or compressing
cycle, air from the compressor enters the air dryer
through the
Fig. 5. AD-2 Operational Charge Cycle
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