Bendix Commercial Vehicle Systems AD-IS AIR DRYER AND RESERVOIR SYSTM - Manual (Page 4)

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FIGURE 2 - BENDIX ® AD-IS ® AIR DRYER AND RESERVOIR SYSTEM CHARGE CYCLE
CHARGE CYCLE (Refer to Figure 2.)
When the compressor is running loaded (compressing air),
compressed air flows through the compressor discharge
line to the inlet (1/IN) port of the air dryer body. The
compressed air often includes contaminates such as oil,
oil vapor, water, and water vapor.
Traveling through the discharge line and into the air dryer,
the temperature of the compressed air falls, causing
some of the contaminants to condense and drop to the
bottom of the air dryer and purge valve assembly . These
contaminants are ready to be expelled at the next purge
cycle. The air then flows into the desiccant cartridge,
where it flows through an oil separator—or coalescing
filter if equipped with a Bendix ® PuraGuard ® oil coalescing
cartridge—which removes water in liquid form as well as
liquid oil and solid contaminants.
Air then flows into the desiccant drying bed and becomes
progressively more dry as water vapor adheres to the
desiccant material in a process known as adsorption.
Dry air exits the desiccant cartridge, through the center of
the base assembly, then flows to the delivery check valve
and through an orifice and into the purge reservoir. The
delivery check valve opens, supplying air to the pressure
protection valves (A) through (D) simultaneously, the
safety valve, and also to the reservoir port of the attached
governor. The purge reservoir fills, storing air that will be
used to regenerate the desiccant during the purge cycle.
This air is available to supply downstream components
during the charge mode.
When the air pressure reaches approximately 106 psi, the
four pressure protection valves will open and air will be
supplied to the primary reservoir, secondary reservoir, and
COMPRESSOR
GOVERNOR
DESICCANT
BED
DELIVERY
CHECK VALVE
(OPEN)
PRIMARY
PORT (PRI)
PURGE VALVE
(CLOSED)
TURBO
CUT-OFF
VALVE
(OPEN) ENGINE
TURBO
UNLOADER
PORT
SUPPLY
PORT
PRIMARY
RESERVOIR
PRESSURE
PROTECTION
VALVES
AUXILIARY PORTS
(TO ACCESSORIES)
SEE
NOTE 1
Note 1:
The Bendix ® AD-IS ® air dryer and reservoir system
purge piston has a purge control channel drain. This
allows any condensation in this area to flow past a
diaphragm in the top of the purge piston and out
through a channel in the middle of the central bolt of
the purge assembly to be drained. During the purge
cycle this drain is closed.
SAFETY
VALVE PURGE
RESERVOIR
DRAIN VALVE
SECONDARY
RESERVOIR
SECONDARY
PORT (SEC)
PURGE
RESERVOIR PURGE
ORIFICE
OIL COALESCING FILTER
(BENDIX ® AD-IS ® PURAGUARD ®
OIL COALESCING AIR DRYER)
A D C B
PURGE
CONTROL
CHANNEL
DIAGRAM SHOWS ALL PRESSURE
PROTECTION VALVES OPEN.