SD-08-2433 ® Bendix® AD-9si™ and AD-9si™ PuraGuard® Oil Coalescing Air Dryer DESICCANT CARTRIDGE (PURAGUARD® OIL COALESCING SHOWN) PT 22 EXTENDED PURGE PORT CON 2-4 UNLOADER TO COMPRESSOR MOUNTING HOLES (3 PER SIDE) HEATER / THERMOSTAT DELIVERY CHECK VALVE COVER OUT 21 DELIVERY PORTS (2) GOVERNOR (GOVERNOR CUT-OUT PRESSURE STAMPED ON COVER) SAFETY VALVE IN 1 SUPPLY FROM COMPRESSOR PURGE VALVE PURGE VALVE 3 GOVERNOR EXHAUST OUT 21 DELIVERY PORTS (2) BOTTOM VIEW FIGURE 1 - BENDIX® AD-9si™ AND AD
GENERAL SAFETY GUIDELINES WARNING! PLEASE READ AND FOLLOW THESE INSTRUCTIONS TO AVOID PERSONAL INJURY OR DEATH: When working on or around a vehicle, the following guidelines should be observed AT ALL TIMES: ▲ Park the vehicle on a level surface, apply the parking brakes and always block the wheels. Always wear personal protection equipment. ▲ Stop the engine and remove the ignition key when working under or around the vehicle.
DESCRIPTION The function of both the Bendix® AD-9si™ air dryer and the Bendix® AD-9si™ PuraGuard® oil coalescing air dryer is to collect and remove air system contaminants in solid, liquid, and aerosol form before they enter the brake system. The AD-9si includes a spin-on style cartridge for easy servicing, and most include a fully integrated governor to control air system charging.
Note 1: The Bendix AD-9si™ air dryer 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.
DESICCANT BED COMPRESSOR OIL COALESCING FILTER CONTROL LINE PURGE ORIFICE PURGE AIR EXTENDED PURGE PORT CONTROL PORT TURBO CUT-OFF VALVE (CLOSED) DELIVERY CHECK VALVE REAR RESERVOIR SUPPLY PORT SAFETY VALVE PURGE VALVE FRONT RESERVOIR EXHAUST EXHAUST GOVERNOR DELIVERY PORT FIGURE 3 - BENDIX® AD-9si™ AIR DRYER WITH GOVERNOR—PURGE CYCLE PURGE CYCLE (Refer to Figures 3 and 5) When air brake system pressure reaches the cut-out setting of the governor, the integral governor unloads the compressor
DESICCANT BED COMPRESSOR OIL COALESCING FILTER CONTROL LINE PURGE ORIFICE PURGE AIR CONTROL PORT EXTENDED PURGE PORT TURBO CUT-OFF VALVE (OPEN) DELIVERY CHECK VALVE REAR RESERVOIR SUPPLY PORT SAFETY VALVE PURGE VALVE FRONT RESERVOIR EXHAUST DELIVERY PORT FIGURE 4 - BENDIX® AD-9si™ AIR DRYER WITHOUT GOVERNOR—CHARGE CYCLE The actual regeneration of the desiccant drying bed begins as dry air from the purge volume flows through the purge orifice into the desiccant bed.
DESICCANT BED COMPRESSOR OIL COALESCING FILTER CONTROL LINE PURGE ORIFICE PURGE AIR EXTENDED PURGE PORT CONTROL PORT REAR RESERVOIR TURBO CUT-OFF VALVE (CLOSED) DELIVERY CHECK VALVE SUPPLY PORT SAFETY VALVE PURGE VALVE FRONT RESERVOIR EXHAUST DELIVERY PORT FIGURE 5 - BENDIX® AD-9si™ AIR DRYER WITHOUT GOVERNOR—PURGE CYCLE TURBO CUT-OFF FEATURE (Refer to Figures 3 and 5) The primary function of the turbo cut-off valve is to prevent loss of engine turbocharger air pressure through the Bendix® AD-
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. Purge valve and governor maintenance is permissible during the warranty period only when using a genuine Bendix® AD-9si™ purge valve governor kit. Because no two vehicles operate under identical conditions, maintenance and maintenance intervals will vary.
1. Visually check for physical damage, such as chafed or broken air and electrical lines, and broken or missing parts. 2. Check the Bendix® AD-9si™ air dryer and mounting bolts for tightness. See Figure 1. Re-torque the three air dryer bolts to 720–912 in-lbs. 3. Perform the Operation & Leakage Tests listed in this publication. 1. This air dryer is intended to remove moisture and other contaminants normally found in the air brake system.
Bendix® AD-9si™ Maintenance Kits DO NOT ATTEMPT TO REMOVE THE CLAMP BAND THAT RETAINS THE TWO HOUSINGS TOGETHER. SERIOUS INJURY OR DEATH MAY OCCUR IF THESE INSTRUCTIONS ARE NOT FOLLOWED COMPLETELY. BENDIX® AD-9si™ AIR DRYER REMOVAL This air dryer removal process is presented in the event it becomes necessary to replace the entire air dryer. Normal service and parts replacement does not require removal of the air dryer from the vehicle. 1.
DESICCANT CARTRIDGE REPLACEMENT KIT HEATER & THERMOSTAT REPLACEMENT KIT SAFETY VALVE HEATER & THERMOSTAT HEATER SCREWS GASKET DELIVERY CHECK VALVE REPLACEMENT KIT DELIVERY SMALL CHECK VALVE BODY O-RING SPRING GOVERNOR SCREWS COVER O-RING GOVERNOR WASHER O-RING O-RING O-RING GOVERNOR KIT PURGE VALVE PURGE VALVE ASSEMBLY RETAINING RING FIGURE 7 - BENDIX® AD-9si™ AIR DRYER SERVICEABLE COMPONENTS that connects the air compressor discharge line to the air dryer inlet fitting.
If, after bypassing the air dryer, the system pressure still does not build, use the following procedure to remove, clean, and reinstall the delivery check valve. ASSEMBLY DELIVERY CHECK VALVE CLEANING PROCEDURE 2. Install the o-ring on the check valve body by sliding the o-ring over the set of four tapered guide lands. The o-ring groove holds the o-ring in its correct location. (Note: This is only required if system pressure does not build after temporary bypass is completed.
BENDIX®AD-9si™ AIR DRYER TROUBLESHOOTING CHART SYMPTOM CAUSE 1. Dryer is constantly “cycling” A. Excessive system leakage. or purging. B. Defective delivery check valve. REMEDY A. Test for excessive system leakage. Allowable leakage observed at dash gauge: - Single vehicle - 1 psi/minute. - Tractor trailer - 3 psi/minute. Using soap solution, test vehicle for leakage at fittings, drain valves and system valves and any accessories (i.e. air suspension).
BENDIX®AD-9si™ AIR DRYER TROUBLESHOOTING CHART SYMPTOM 2. Water in vehicle reservoirs. CAUSE REMEDY A. Maximum air dryer inlet temperature is A. Check for excessive carbon build-up in compressor discharge exceeded due to improper discharge line. Replace if required. Make certain that discharge line line length. length is at least 6 ft. Increase discharge line length and/or diameter to reduce air dryer inlet temperature. B. Ambient temperature exceeds 125°F. B.
BENDIX®AD-9si™ AIR DRYER TROUBLESHOOTING CHART SYMPTOM CAUSE REMEDY 5. Cannot build system air A. Supply pressure to the air dryer is not A. Ensure the supply pressure to the air dryer is greater than pressure. sufficient. 110 psi during the system charge. B. Kinked or blocked (plugged) discharge B. Check to determine if air passes through discharge line. line. Check for kinks, bends, excessive carbon deposits, or ice blockage. C. Excessive bends in discharge line C.
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