Bendix Commercial Vehicle Systems AD-SP SYSTEM PURGE AIR DRYER 10/04 - Manual (Page 6)

6
CARTRIDGE
BOLT
PURGE
VOLUME
DELIVERY
PORT
CHECK
VALVE
(BLACK)
PURGE
VALVE
TURBO
CUT-OFF
VALVE
SUPPLY
PORT
CONTROL
PORT
OIL
SEPARATOR
FIGURE 4 - BENDIX ® AD-IP ® AIR DRYER SECTIONAL VIEW
DESICCANT
BED
PURGE
ORIFICE
DESICCANT
CARTRIDGE
New Style End Cover - Horizontal Delivery Check Valve
SPRING
O-RING
PIPE PLUG
CARTRIDGE
BOLT
DELIVERY
PORT
Old Style End Cover -Vertical Delivery Check Valve
CHECK VALVE
(WHITE)
FIGURE 5 - AD-IP ® INTEGRAL PURGE AIR DRYER TURBO
CUT-OFF
SUPPLY
PORT
TURBO
CUT-OFF
VALVE
CONTROL
PORT
PURGE
VALVE
The actual reactivation of the desiccant drying bed begins
as dry air flows from the purge volume through the purge
orifice in the desiccant cartridge bolt, then through the
center of the bolt and into the desiccant bed. Pressurized
air from the purge volume expands after passing through
the purge orifice; its pressure is lowered and its volume
increased. The flow of dry air through the drying bed
reactivates the desiccant material by removing the water
vapor adhering to it. Generally 30 seconds are required for
the entire purge volume of a standard Bendix ® AD-IP ® air
dryer to flow through the desiccant drying bed.
The delivery check valve assembly prevents air pressure in
the brake system from returning to the air dryer during the
purge cycle. After the 30 second purge cycle is complete
the desiccant has been reactivated or dried. The air dryer
is ready for the next charge cycle to begin. However the
purge valve will remain open and will not close until air
brake system pressure is reduced and the governor signals
the compressor to charge the system.
TURBO CUT-OFF FEATURE (Refer to Figure 5)
The primary function of the turbo cut-off valve is to
prevent loss of engine turbocharger air pressure through
the AD-IP air dryer in systems where the compressor
intake is connected to the engine turbocharger. The turbo
cut-off valve also removes the “puffing” of air out the open
purge exhaust when a naturally aspirated, single cylinder
compressor, equipped with an inlet check valve, is in use.