Bendix Commercial Vehicle Systems AD-IS EVERFLOW - Manual (Page 5)

5
FIGURE 4 - BENDIX ® AD-IS ® AIR DRYER AND RESERVOIR SYSTEM PURGE CYCLE
DIAGRAM SHOWS ALL PRESSURE
PROTECTION VALVES OPEN.
COMPRESSOR
GOVERNOR
DESICCANT
BED
DELIVERY
CHECK VALVE
(CLOSED)
PRIMARY
PORT (PRI)
PURGE VALVE
(OPEN)
TURBO
CUT-OFF
VALVE
(CLOSED) ENGINE
TURBO
UNLOADER
PORT
SUPPLY
PORT
PRIMARY
RESERVOIR
PRESSURE
PROTECTION
VALVES
AUXILIARY PORTS
(TO ACCESSORIES)
EXHAUST
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
Air then moves into the desiccant drying bed and becomes
progressively drier as water vapor adheres to the desiccant
material in a process known as “ADSORPTION.” Dry air
exits the desiccant cartridge through the delivery check
valve and also through an orifice into the purge reservoir.
The delivery check valve opens, supplying air to pressurize
the air brake system. The purge reservoir stores air that will
be used to reactivate the desiccant during the purge cycle.
From a flat system — approximately 80 psi — the Bendix
®
AD-IS ® EverFlow ® electronic module is actuated and
begins the purge cycle. When the air pressure reaches
the specified opening pressure — typically 106 psi — the
pressure protection valves will open and air will be supplied
to the primary reservoir, secondary reservoir or other
accessories. If the pressure protection valves are preset
to different values, the valves will open in order of lowest
setting to highest setting when charging a flat system.
The air dryer will remain in the charge cycle until the air
brake system pressure builds to the governor cut-out
setting of approximately 130 psi When air brake system
pressure reaches the cut-out setting of the governor,
the governor unloads the compressor and the electronic
module sends a signal to one of the air dryers to purge.
The governor unloads the compressor by allowing air
pressure to fill the line leading to the compressor unloader
mechanism — causing the delivery of compressed air to
the Bendix ® AD-IS ® EverFlow ® assembly to be suspended.
Similarly, the governor also supplies air pressure to the
EverFlow electronic module. The electronic module uses
this signal to determine the volume of air in the brake
system. If the volume is normal, the electronic module
sends a signal to the control port on the proper dryer. If the