BENDIX SD-08-2412 manual Turbo CUT-OFF Feature Refer to Figure, Preventive Maintenance

		←			←
←	←	←			←
			←	←	←
		←
SUPPLY
PORT		←

TURBO	←	←	PURGE
			VALVE
CUT-OFF				CHECK
PISTON			DISCHARGE
	EXHAUST			VALVE
			LINE	ASSEMBLY

FIGURE 4 - BENDIX® AD-9®AND AD-9®IPC AIR DRYER

TURBO CUT-OFF

The initial purge and desiccant cartridge decompression lasts only a few seconds and is evidenced by an audible burst of air at the Bendix® AD-9®or AD-9®IPC air dryer exhaust.

The actual reactivation of the desiccant drying bed begins as dry air flows from the purge volume through the desiccant cartridge purge orifice and into the desiccant drying 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 15–30 seconds are required for the entire purge volume of a standard Bendix AD-9 or AD-9 IPC air dryer to flow through the desiccant drying bed.

The end cover single 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 air dryer is ready for the next charge cycle to begin.

The purge valve will remain open after the purge cycle is complete, and will not close until air brake system pressure is reduced and the governor signals the compressor to charge.

TURBO CUT-OFF FEATURE (Refer to Figure 4)

The primary function of the turbo cut-off valve is to prevent loss of engine turbocharger air pressure through the Bendix AD-9 and AD-9 IPC air dryers in systems where the compressor intake is connected to the engine turbocharger. The turbo cut-off valve also reduces the “puffing” of air out

4

UPPER			UPPER
BRACKET
			BRACKET
STRAP
DESICCANT
CARTRIDGE
DESICCANT			HOUSING
BED
OIL			LOWER
SEPARATOR			BRACKET
CONTROL
PORT
SUPPLY			BW
PORT
			CHECK
			VALVE
TURBO			ASSEMBLY
CUT-OFF
PISTON	PURGE VALVE	PURGE	DISCHARGE
	HOUSING	VALVE	PORT
	ASSEMBLY
FIGURE 5 - BENDIX® AD-9®AND AD-9®IPC AIR DRYER

CROSS SECTION

the open exhaust when a naturally aspirated, single cylinder compressor equipped with an inlet check valve is in use.

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 air dryer inlet port is restricted from entering the air dryer. While the turbo cut-off effectively prevents loss of turbocharger boost pressure to the engine, some “seepage” of air may be detected under certain conditions of compressor engine and turbocharger 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.