BENDIX AD-9 AIR DRYER User's Manual | Page 4

BENDIX Dryer User's Manual - AD-9 AIR DRYER.
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FIGURE 4 - AD-9™ AIR DRYER TURBO CUTOFF

At the onset of the purge cycle, the downward travel of the
purge piston is stopped when the turbo cut-off valve (tapered
portion of purge piston) contacts its mating metal seat in
the purge valve housing. With the turbo cut-off valve seated
(closed position), air in the discharge line and AD-9™ air
dryer inlet port is restricted from entering the air dryer. While
the turbo cut-off effectively prevents loss of turbo charger
boost pressure to the engine, some “seepage” of air may be
detected under certain conditions of compressor engine and
turbo charger operation, even so there will always be low
pressure trapped in the discharge line.

PREVENTIVE MAINTENANCE

Important: Review the warranty policy before performing
any intrusive maintenance procedures. An extended warranty
may be voided if intrusive maintenance is performed during
this period.  Note:  It is acceptable for the purge valve to be
maintained as necessary, i.e., the installation of a purge
valve maintenance kit, without voiding the warranty.

Because no two vehicles operate under identical conditions,
maintenance and maintenance intervals will vary. Experience
is a valuable guide in determining the best maintenance
interval for any one particular operation.

Every 900 operating hours or 25,000 miles or every three
(3) months:

1. Check for moisture in the air brake system by opening

reservoirs, drain cocks, or valves and checking for
presence of water. If moisture is present, the desiccant
may require replacement; however, the following
conditions can also cause water accumulation and
should be considered before replacing the desiccant:

UPPER

BRACKET

CHECK

VALVE

ASSEMBLY

SUPPLY

PORT

UPPER

BRACKET

STRAP

DESICCANT
CARTRIDGE

LOWER

BRACKET

HOUSING

CHECK

VALVE

ASSEMBLY

DISCHARGE

LINE

TURBO

CUTOFF

PISTON

EXHAUST

PURGE

VALVE

TURBO

CUTOFF

PISTON

A. An outside air source has been used to charge the

system. This air did not pass through the drying bed.

B. Air usage is exceptionally high and not normal for a

highway vehicle. This may be due to accessory air
demands or some unusual air requirement that does
not allow the compressor to load and unload
(compressing and non-compressing cycle) in a
normal fashion. Check for high air system leakage.
If the vehicle vocation has changed it may be
necessary to upgrade the compressor size. Refer to
Appendix A, Table A and the column entitled Vehicle
Vocation.

C. The air dryer has been installed in a system that

has been previously used without an air dryer. This
type of system will be saturated with moisture and
several weeks of operation may be required to dry it
out.

D. Location of the air dryer is too close to the air

compressor. Refer to Locating AD-9™ Air Dryer On
Vehicle
 section and Appendix A, Table A, column 2
for discharge line length.

E. In areas where more than a 30 degree range of

temperature occurs in one day, small amounts of
water can accumulate in the air brake system due
to condensation. Under these conditions, the
presence of small amounts of moisture is normal

PURGE VALVE

HOUSING

ASSEMBLY

PURGE

VALVE

DISCHARGE

PORT

FIGURE 5 - AD-9™ AIR DRYER SECTIONAL VIEW

DESICCANT

BED

OIL

SEPARATOR

CONTROL

PORT

SUPPLY

PORT

 

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