BENDIX AD-4 Installation guide
SD-08-2407 В® BendixВ® AD-4в„ў Air Dryer UPPER BRACKET UPPER BRACKET LOWER BRACKET LOWER BRACKET SUPPLY PORT CONTROL PORT SUPPLY PORT THERMOSTAT TERMINAL PURGE EXHAUST EXTENDED PURGE AD-4в„ў AIR DRYER DELIVERY PORT PURGE EXHAUST STANDARD AD-4в„ў AIR DRYER FIGURE 1 - AD-4в„ў AIR DRYER MODELS DESCRIPTION The function of the AD-4в„ў air dryer is to collect and remove air system contaminants in solid, liquid and vapor form before they enter the brake system. It provides clean, dry air to the components of the brake system which increases the life of the system and reduces maintenance costs. Daily manual draining of the reservoirs is eliminated. The AD-4в„ў air dryer consists of a desiccant cartridge and a die cast aluminum end cover secured to a cylindrical steel outer shell with eight cap screws and nuts. The end cover contains a check valve assembly, a safety valve, purge valve mechanism, a cast-in heater element with a replaceable thermostat assembly and three threaded air connections. The three air connections are identified with embossed numbers and lettering. The identification and function of each is as follows: Port l.D. Function/Connection CON 4 ................ Control Port (from unloader port on governor). SUP 11 .............. Supply Port (air in). DEL 2 ................ Delivery Port (air out). A cast-in heater element and replaceable thermostat with an external terminal are provided. The voltage and wattage requirements of the heater and thermostat are shown with embossed numbers and letters in the recess adjacent to the control port marked вЂњCON.вЂќ 1 CHECK VALVE ORIFICE PURGE VOLUME DESICCANT CARTRIDGE DESICCANT BED OIL SEPARATOR CHECK VALVE DELIVERY PORT HEATER EXHAUST PORT CONTROL GOVERNOR PURGE VALVE COMPRESSOR SUPPLY RESERVOIR FIGURE 2 - AD-4в„ў AIR DRYER CHARGE CYCLE OPERATION OF THE AD-4в„ў AIR DRYER The AD-4в„ў air dryer alternates between two operational modes or вЂњcyclesвЂќ during operation: the charge cycle and the purge cycle. The following description of operation is separated into these вЂњcyclesвЂќ of operation. CHARGE CYCLE (refer to Figure 2) When the compressor is loaded (compressing air) compressed air, along with oil, oil vapor, water and water vapor flows through the compressor discharge line to the supply port of the air dryer end cover. The flow velocity or the speed at which the air and its contaminants travel down the discharge line is reduced substantially as it enters the air dryer end cover baffle system behind the supply port. As air travels through the baffle system, its direction of flow changes by 180 degrees several times, reducing the temperature, causing contaminants to condense and drop to the bottom or sump of the air dryer end cover. After exiting the end cover baffle system, the air flows into the desiccant cartridge. Once in the desiccant cartridge air first flows through an oil separator which removes water in liquid form as well as oil, oil vapor and solid contaminants. 2 Air exits the oil separator and enters the desiccant drying bed. Air flowing through the column of desiccant becomes progressively dryer as water vapor adheres to the desiccant material in a process known as вЂњadsorptionвЂќ. The desiccant cartridge using the adsorption process typically removes 95% of the water vapor from the pressurized air. The majority of dry air exits the desiccant cartridge through its integral single check valve to fill the purge volume between the desiccant cartridge and outer shell. Some air will also exit the desiccant cartridge through the purge orifice adjacent to the check valve. Dry air flows out of the purge volume through the single check valve assembly and out the delivery port to the first (supply) reservoir of the air system. The air dryer will remain in the charge cycle until air brake system pressure builds to the governor cutout setting. PURGE CYCLE (refer to Figure 3) When air brake system pressure reaches the cutout setting of the governor, the compressor unloads (air compression stopped) and the purge cycle of the air dryer begins. The CHECK VALVE ORIFICE PURGE VOLUME DESICCANT CARTRIDGE DESICCANT BED OIL SEPARATOR CHECK VALVE DELIVERY PORT EXHAUST PORT CONTROL GOVERNOR HEATER PURGE VALVE COMPRESSOR SUPPLY RESERVOIR FIGURE 3 - AD-4в„ў AIR DRYER PURGE CYCLE line connecting the governor unloader port to the AD-4в„ў air dryer end cover control port is pressurized when the governor unloads the compressor. Air pressure at the AD-4в„ў air dryer end cover control port is also present on the purge valve piston. The purge piston moves in response to air pressure causing the purge valve to open to atmosphere. Contaminants in the end cover sump are expelled immediately when the purge valve opens. Also, air which was flowing through the desiccant cartridge changes direction and begins to flow toward the open purge valve. Oil, water and solid contaminants collected by the oil separator are removed by air flowing from the desiccant drying bed to the open purge valve. The initial purge and desiccant cartridge decompression lasts only a few seconds and is evidenced by an audible burst of air at the AD-4в„ў 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 AD-4в„ў 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. 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. 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. 3 CHECK VALVE PURGE ORIFICE PURGE VOLUME DESICCANT CARTRIDGE DESICCANT BED CHECK VALVE ASSEMBLY PERFORATED PLATE OIL SEPARATOR NUT SEALING RING WASHER SEALING RING SEALING RING SEALING RING END COVER SPECIAL WASHER HEX HEAD SCREW SPRING DELIVERY PORT PURGE VALVE EXHAUST DIAPHRAGM PURGE PISTON EXHAUST COVER SUPPLY PORT O-RING FIGURE 4 - AD-4в„ў AIR DRYER SECTIONAL VIEW 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: 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. 4 C. The air dryer has been installed in a system that has been previously used without an air dryer. This type 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-4в„ў 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 and should not be considered as an indication that the dryer is not performing properly. Note: A small amount of oil in the system may be normal and should not, in itself, be considered a reason to replace the desiccant; oil stained desiccant can function adequately. 2. Check mounting bolts for tightness. Retorque to 270385 inch pounds. 3. Perform the Operation & Leakage Tests listed in this publication. 6. Check the operation of the end cover heater and thermostat assembly during cold weather operation as follows: A. Electric Power to the Dryer With the ignition or engine kill switch in the ON position, check for power at the dryerвЂ™s electrical terminal using a voltmeter or test light. On a single terminal AD-4в„ў air dryerвЂ™s disconnect the lead wire at the end cover terminal post. Place the test leads on the lead wire and a GOOD vehicle ground. On dual terminal AD-4в„ў air dryerвЂ™s disconnect both lead wires at the end cover terminal posts. If there is no voltage indicated, look for a blown fuse, broken wires, or corrosion in the vehicle wiring harness. Check to see if a good ground path exists. Every 10,800 hours or 300,000 miles or 36 months: 1. Rebuild the air dryer including the desiccant cartridge. Note: The desiccant change interval may vary from vehicle to vehicle. Although typical desiccant cartridge life is three years, many will perform adequately for a longer period of time. In order to take maximum advantage of desiccant life and assure that replacement occurs only when necessary, it is important that Operation & Leakage Tests be performed. WARNING! This air dryer is intended to remove moisture and other contaminants normally found in the air brake system. Do not inject alcohol, anti-freeze, or other de-icing substances into or upstream of the air dryer. Alcohol is removed by the dryer, but reduces the effectiveness of the device to dry air. Use of other substances can damage the air dryer and may void the warranty. B. Thermostat and Heater Operation Turn off the ignition switch and cool the end cover assembly to below 40 degrees Fahrenheit. Using an ohmmeter, check the resistance between the electrical terminal and the metal end cover (see Figure 5). (Note: On the dual terminal end cover, check the resistance between the two terminals.) The OPERATION & LEAKAGE TESTS 1. Test the outlet port check valve assembly by building the air system to governor cut-out and observing a test air gauge installed in the supply reservoir. A rapid loss of pressure could indicate a failed outlet port check valve. (Note: Purge valve will be open when governor cut-out pressure is reached. Allow 45 seconds after governor cut-out occurs to complete the purge cycle before testing the check valve.) Coat the exhaust with a soap solution. Leakage should not exceed a 1" bubble in 1 second. 2. Check for excessive leakage around the purge valve. With the compressor in loaded mode (compressing air), apply a soap solution to the purge valve housing assembly exhaust port and observe that leakage does not exceed a 1" bubble in 1 second. If the leakage exceeds the maximum specified, service the purge valve housing assembly. 3. Close all reservoir drain cocks. Build up system pressure to governor cut-out and note that AD-4в„ў air dryer purges with an audible escape of air. вЂњFanвЂќ the service brakes to reduce system air pressure to governor cut-in. Note that the system once again builds to full pressure and is followed by an AD-4в„ў air dryer purge. 4. Check the operation of the safety valve by pulling the exposed stem while the compressor is loaded (compressing air). There must be an exhaust of air while the stem is held and the valve should reseat when the stem is released. 5. Check all lines and fittings leading to and from the air dryer for leakage and integrity. HEATER POST 1 9 8 9 A 10 7 B 11 6 THERMOSTAT COVER 1 5 4 3 1 2 SINGLE WIRE SYSTEM BOLD NUMBERS ARE ITEMS IN MAINTENANCE KITS 1 9 11 10 8 7 6 5 BOOT 4 3 2 1 BOOT CONNECTIONS FOR POWER AND INSULATED RETURN DUAL WIRE SYSTEM FIGURE 5 - AD-4в„ў AIR DRYER SINGLE AND DUAL TERMINAL THERMOSTAT ASSEMBLIES 5 resistance should be 2.0 to 4.0 ohms for the 12 volt, 60 watt end cover and 4.0 - 7.0 ohms for the 24 volt, 120 watt end cover. These resistance values apply to either single or dual terminal air dryer end covers. Warm the end cover assembly to over 90 degrees Fahrenheit and again check the resistance as above. The resistance should exceed 1000 ohms for both single and dual terminal air dryers. If the resistance values obtained are within the stated limits, the thermostat and heater assembly is operating properly. If the resistance values obtained are outside the stated limits, proceed to Step C to determine the cause. C. Heater Element Inspection With the ignition or engine control switch вЂњoffвЂќ, remove the thermostat cover (see Figure 5). Using an ohmmeter, check the resistance between the metal end cover and the heater post (see Figure 5). (Note: On the dual terminal end cover, check the resistance between the two terminals.) For a 12 volt, 60 watt end cover, the resistance should be 2.0 - 2.8 ohms and for a 24 volt, 120 watt end cover, 4.0 - 5.6 ohms. These resistance values apply to either single or dual terminal air dryer end covers. If the heater resistance value obtained is outside the stated limits, a new or remanufactured end cover should be installed, since the heater element cannot be serviced. Check that a good ground path exists between the air dryer end cover casting and the vehicle chassis. Correct if needed. If the heater resistance value obtained is within the stated limits the thermostat should be replaced (Kit Number 102657) or a new or remanufactured end cover installed. Note: The dual terminal air dryer cover requires kit number 103982. D. Reassembly Reinstall the thermostat cover as illustrated in Figure 5. Take special care to assure the rubber spacer and the gasket are correctly installed, to assure proper operation. REBUILDING THE AD-4в„ў AIR DRYER GENERAL If, after completing the routine operation and leakage tests, it has been determined that one or more components of the air dryer requires replacement or maintenance, refer to the following list to find the appropriate kit(s). When rebuilding or replacing components of the air dryer use only genuine Bendix parts. For ease in servicing the AD-4 в„ў air dryer desiccant cartridge assembly, it is recommended that the air dryer be removed from the vehicle. 6 MAINTENANCE KITS AVAILABLE: 103817 Major Maintenance Kit This kit contains the parts necessary to completely rebuild the AD-4в„ў air dryer (desiccant cartridge included) and includes kit 103980. 103818 AD-4в„ў Air Dryer Purge Valve Maintenance Kit This kit contains the parts necessary to rebuild the AD-4в„ў air dryer end cover purge valve only. 103879 AD-4в„ў Air Dryer Seal Kit This kit contains the outlet port check valve and the o-rings and seals required when removing the end cover assembly. This kit is included with kits 103980 and 103981. 103980 End Cover Maintenance Kit This kit contains the parts necessary to rebuild the end cover of the AD-4в„ў air dryer and includes kit 103818. 103981 Desiccant Cartridge Replacement Kit This kit contains the parts necessary to change the desiccant cartridge only. 102657 Thermostat Maintenance Kit (single terminal models) This kit contains the parts necessary to rebuild a single terminal thermostat assembly in the AD-4в„ў air dryer. 103982 Thermostat Maintenance Kit (dual terminal models) This kit contains the parts necessary to rebuild a two terminal thermostat assembly (insulated ground). 288918 Thermostat Cover Replacement Kit (single terminal models) This kit contains the necessary components for replacing the non-metallic thermostat cover. 104964 Thermostat Cover Replacement Kit (dual terminal models) This kit contains the necessary components for replacing the non-metallic thermostat cover. WARNING! PLEASE READ AND FOLLOW THESE INSTRUCTIONS TO AVOID PERSONAL INJURY OR DEATH: When working on or around a vehicle, the following general precautions should be observed at all times. 1. Park the vehicle on a level surface, apply the parking brakes, and always block the wheels. Always wear safety glasses. 2. Stop the engine and remove ignition key when working under or around the vehicle. When working in the engine compartment, the engine should be shut off and the ignition key should be removed. Where circumstances require that the engine be in operation, EXTREME CAUTION should be used to prevent personal injury resulting from contact with moving, rotating, leaking, heated or electrically charged components. MOUNTING STRAP LOCKWASHER CAP SCREW 5/16вЂќ X 4-1/2вЂќ NUT SEALING RING BRACKET MOUNTING STRAP LOCKWASHER CAP SCREW 5/16вЂќ X 4-1/2вЂќ BRACKET SEALING PLATE NUT MOUNTING BRACKET HOOK (4) DESICCANT CARTRIDGE CAP SCREW & LOCKWASHER (8) LOCK NUT (8) SPECIAL WASHER SEALING RING AIR DRYER HOUSING SEALING RING PURGE PISTON O-RING SPRING CONTROL PORT CHECK VALVE ASSEMBLY SUPPLY PORT DELIVERY PORT END COVER HEATER VOLTAGE SHOWN SPECIAL WASHER (8) CAP SCREW 3/8вЂќ SAFETY VALVE DESICCANT CARTRIDGE PURGE VALVE EXHAUST DIAPHRAGM 1/2вЂќ CAP SCREW EXHAUST COVER SCREW SEALING RING THERMOSTAT ASSEMBLY FIGURE 6 - AD-4в„ў AIR DRYER ASSEMBLY 7 3. Do not attempt to install, remove, disassemble or assemble a component until you have read and thoroughly understand the recommended procedures. Use only the proper tools and observe all precautions pertaining to use of those tools. 4. If the work is being performed on the vehicleвЂ™s air brake system, or any auxiliary pressurized air systems, make certain to drain the air pressure from all reservoirs before beginning ANY work on the vehicle. If the vehicle is equipped with an AD-ISв„ў air dryer system or a dryer reservoir module, be sure to drain the purge reservoir. 5. Following the vehicle manufacturerвЂ™s recommended procedures, deactivate the electrical system in a manner that safely removes all electrical power from the vehicle. 6. Never exceed manufacturerвЂ™s recommended pressures. 7. Never connect or disconnect a hose or line containing pressure; it may whip. Never remove a component or plug unless you are certain all system pressure has been depleted. 8. Use only genuine Bendix В® replacement parts, components and kits. Replacement hardware, tubing, hose, fittings, etc. must be of equivalent size, type and strength as original equipment and be designed specifically for such applications and systems. 9. Components with stripped threads or damaged parts should be replaced rather than repaired. Do not attempt repairs requiring machining or welding unless specifically stated and approved by the vehicle and component manufacturer. 10. Prior to returning the vehicle to service, make certain all components and systems are restored to their proper operating condition. 11. For vehicles with Antilock Traction Control (ATC), the ATC function must be disabled (ATC indicator lamp should be ON) prior to performing any vehicle maintenance where one or more wheels on a drive axle are lifted off the ground and moving. в„ў AD-4 AIR DRYER REMOVAL 1. Park the vehicle on a level surface and prevent movement by means other than the brakes. 2. Drain all reservoirs to 0 p.s.i. (0 kPa).вЂ” Caution: Compressor discharge line may still contain residual pressure. 3. Identify and disconnect the three air lines from the end cover and note the position of end cover ports relative to the vehicle. 4. Pull boot from the thermostat and heater cover and slide it onto the wire to expose the connection. Remove nut and disconnect electrical wire from the terminal. Note: Vehicles with insulated ground (2 wire) system will have two boots and two terminals to be disconnected. (See Figures 5 & 8.) 5. Loosen the 5/16" X 4-1/2" hex bolt securing the upper and lower mounting straps. Disengage the mounting 8 LOWER RIGHT ANGLE BRACKET END COVER LOCK NUT EXTRA LONG CAP SCREW SPECIAL WASHER FIGURE 7 - LOWER BRACKET INSTALLATION bracket hook from the end cover (Refer to Figure 6.) Note: If the AD-4в„ў air dryer being serviced has a right angle bracket instead of a lower mounting strap and safety hook, proceed to step 6, otherwise proceed to step 7. 6. Remove, retain and mark the two 3/8" end cover cap screws, lock nuts and four special washers that retain the lower mounting bracket to the end cover, also mark these two holes of the end cover. (These bolts are longer than the other 6 bolts.) 7. Remove the AD-4в„ў air dryer from its mounting brackets on the vehicle. DISASSEMBLY The following disassembly and assembly procedure is presented for reference purposes and presupposes that a major rebuild of the AD-4в„ў air dryer is being undertaken. Several replacement parts and maintenance kits are available which do not require full disassembly. The instructions provided with these parts and kits should be followed in lieu of the instructions presented here. Refer to Figure 6 during disassembly. Caution: While performing service on the AD-4в„ў air dryer, it is not recommended that a clamping device (vise, C-clamp, etc.) be used to hold any die cast aluminum component as damage may result. To hold the end cover, install a pipe nipple in the supply port and clamp the nipple into a vise. 1. Remove the remaining 3/8" lock nuts, special washers and cap screws from the flange of the air dryer and separate the end cover from the air dryer outer housing. Separate the desiccant cartridge and sealing plate from the end cover. Remove and discard the three sealing rings. One sealing ring is located in the groove on the sealing plate and the other two are in grooves in the end cover. 2. Remove 1/4" cap screw from the bottom of the purge valve and remove the diaphragm washer, exhaust diaphragm and purge valve. Discard the exhaust diaphragm and purge valve. Remove purge piston. Note: Hold piston down when removing cap screw due to spring tension. 3. Remove and discard the check valve assembly in the recess at the delivery port of the end cover. 4. Remove the safety valve from the end cover (only if it has been determined that it needs replacement during service checks). 5. To remove the thermostat see the appropriate section in this manual (only if it has been determined that it needs replacement during service checks). 6. Remove purge piston and spring from the top side of the cover. 7. Remove o-ring from the purge piston and discard the o-ring. 8. Remove the four 1/4" cap screws and lockwashers that secure the sealing plate to the desiccant cartridge. Separate the sealing plate from the desiccant cartridge and discard the sealing ring at the base of the cartridge. CLEANING & INSPECTION 1. Using mineral spirits or an equivalent solvent, clean and thoroughly dry all metal parts. 2. Inspect the interior and exterior of all metal parts that will be reused for severe corrosion, pitting and cracks. Superficial corrosion and or pitting on the exterior portion of the upper and lower body halves is acceptable. 3. Inspect the bores of both the end cover for deep scuffing or gouges. 4. Make certain that all purge valve housing and end cover passages are open and free of obstructions. 5. Inspect the pipe threads in the end cover. Make certain they are clean and free of thread sealant. 6. Inspect the purge valve housing bore and seat for excessive wear and scuffing. 7. Inspect the purge valve piston seat for excessive wear. 8. Inspect all air line fittings for corrosion. Clean all old thread sealant from the pipe threads. 9. All o-rings removed should be discarded and replaced with new o-rings provided in appropriate kit(s). Any component exhibiting a condition described in step 1 to 8 should be replaced. ASSEMBLY Prior to assembly, coat all o-rings, o-ring grooves, and bores with a generous amount of barium base lubricant. Important Note: The single exception to prelubrication is the sealing ring between the desiccant cartridge and sealing plate. Refer to step number 8 for proper installation of this sealing ring. Refer to Figure 6 during assembly unless otherwise advised. 1. Place return spring into cavity in the center of top side of end cover. 2. Install the purge piston o-ring on the purge piston and place the purge piston inside the return spring installed in Step 2. 3. Turn end cover over on a flat clean surface (making sure purge piston and return spring remain in proper position.) Compress the return spring by pushing down on the end cover and align square shank of purge piston into mating hole in the end cover. 4. Place the diaphragm washer, diaphragm, and purge valve onto the 1/4" cap screw. 5. Install the 1/4" cap screw with parts on it into exhaust cover and torque to 60-80 inch pounds. 6. Install safety valve (if removed) and torque to 120-400 inch pounds, making sure that the exhaust hole is pointed downward when the dryer is installed. 7. Install thermostat (if removed). Refer to instructions pertaining to thermostat installation under section Thermostat Assembly. 8. Place sealing ring on bottom of desiccant cartridge. The desiccant cartridge, sealing ring and sealing plate should be wiped and free of lubricant prior to this assembly procedure. Attach cartridge to plate (smooth side of plate opposite cartridge) with four 1/4" socket head cap screws and lockwashers. Torque to 80-100 inch pounds. 9. Install the two sealing rings in the recesses of the end cover. 10. Install the check valve assembly into the end cover making sure the tang on the check valve assembly fits into the mating recess in the end cover. 11. Place desiccant cartridge and sealing plate assembly onto end cover. (Taking care not to displace sealing rings.) The large hole in the sealing plate must line up with the check valve and spiral pins in the sealing plate must enter corresponding holes in the end cover. 12. Install the outer sealing ring on the sealing plate. Place the outer housing over the desiccant cartridge (lining up marks made on the outer housing and end cover prior to disassembly) and retain with eight 3/8" hex head bolts, special washers, and lock nuts. Refer to Figure 8 for torque pattern. Torque to 270-385 inch pounds. Note: If 9 3/8" bolts require replacement, insure that the replacement bolts are grade 5 minimum and the same length as the original bolts. Use of inferior bolts can compromise the integrity of the air dryer and lead to premature failure. Where a lower, right angle mounting bracket (instead of a lower mounting strap) is used; line up the marks made on the outer housing and end cover. Install the six (standard) 3/8" cap screws, lock nuts and twelve special washers. The two longer 3/8" cap screws will be used to secure the AD-4в„ў air dryer to the right angle mounting bracket. Note: If during the Operation & Leakage Tests it was determined that the thermostat was inoperative, use the following procedure for repair or replacement. It is not necessary to replace this unit each time the end cover is rebuilt. Use thermostat maintenance kit 102657 for single terminal application. For dual terminal application, use kit #103982. (See Figure 5.) 5. Cut uninsulated thermostat wire at Point B, remove and discard thermostat and terminal assembly (1). 6. Clean remaining wire attached to heater terminal. 7. Clean thermostat вЂњpocketвЂќ in end cover (9). THERMOSTAT ASSEMBLY (Refer to Figure 5) 1. Cut uninsulated lead of new thermostat (1) at Point A. 2. Install thermostat in end cover pocket and position uninsulated leads next to each other. 3. Using a soldering heat sink, clamp uninsulated leads at Point B and solder leads with straight rosin core solder. Do not use acid core solder as corrosion can result. Clean excess solder off end cover. 4. Install thermostat terminal (1) in cover (6). THERMOSTAT DISASSEMBLY (Refer to Figures 5 5. Install o-ring (5), washer (4), and nut (2). Torque nut to 20-30 inch pounds. Then install lockwasher (3) and nut (2) finger tight to allow for reconnection of electrical wire when reinstalled on vehicle. and 8) 6. Install spacer (11) over thermostat (1). 1. Remove nut (2), then lockwasher (3), plain washer (4), nut (2) and o-rings (5). Discard o-ring and retain other parts. 7. Install gasket (7) and thermostat cover (6) and secure thermostat cover to end cover (9) using screws (7) and lockwashers (8). 2. Remove and retain four Phillips head screws (7) and cover (6). 8. Torque to 20-30 inch pounds. A. At a temperature above 90 degrees Fahrenheit, check resistance between thermostat terminal (1) and end cover (9). Resistance should be 1,000 ohms or greater; if not, check for solder вЂњpathвЂќ short. 3. Remove and discard gasket (10). 4. Remove and retain spacer (11). DELIVERY PORT SAFETY VALVE 6 9. Test thermostat as follows: 2 HEATER VOLTS/WATTS EMBOSSED HERE CONTROL PORT B. Chill entire end cover assembly to 40 degrees Fahrenheit or below and check resistance again. Resistance should be 2-4 ohms for a 12 volt, 60 watt end cover and 4-7 ohms for a 24 volt, 120 watt end cover. 4 5 UNLOADER вЂњUNLвЂќ PORT SUPPLY PORT 1&9 3 7 AD-4в„ў AIR DRYER SUP 8 MOUNTING BRACKET HOOK FIGURE 8 - AD-4в„ў AIR DRYER END COVER WITH TORQUE PATTERN 10 COMPRESSOR GOVERNOR RESERVOIR вЂњRESвЂќ PORT CON 8-10 AMP FUSE TO IGNITION DEL SUPPLY RESERVOIR FIGURE 9 - AD-4в„ў AIR DRYER INSTALLATION SCHEMATIC RE-INSTALLATION 1. Install the assembled AD-4в„ў air dryer (if an AD-4в„ў air dryer with a lower right angle bracket instead of a lower mounting strap is being serviced proceed to step #2) on the vehicle by sliding it into mounting brackets until mounting bracket hook catches under the lip of the cover. Proceed to step #3. 2. Install the assembled AD-4в„ў air dryer back onto the vehicle by slipping it into the upper mounting bracket. Align the two unused holes in the end cover with the bottom mounting bracket such that the bottom bracket supports air dryer. The AD-4в„ў air dryer end cover should rest on the bracket. Using the remaining two 3/8" cap screws, four special washers, and two locknuts, secure the air dryer to the lower bracket. Tighten, then torque the two remaining cap screws to 270-385 in. Ibs. 3. Tighten the 5/16" x 4-1/2" bolt and nut on the upper mounting bracket. Torque to 80-120 in Ibs. 4. Reconnect the three airlines to the proper ports on the end cover (identified during disassembly). 5. Reconnect the thermostat and heater wire and place boot in position to protect connection by forcing it over knob on plastic cover. 6. Before placing vehicle back into service, perform the Operation and Leakage Tests stated elsewhere in this manual. RETROFITTING THE AD-4в„ў AIR DRYER GENERAL The following retrofit instructions are presented for reference purposes only since Bendix aftermarket retrofit and replacement air dryers are packaged with the most up-todate installation instructions. The instructions packaged with the AD-4в„ў air dryer should be followed in lieu of those presented here. The preceding portion of this manual deals with вЂњin-serviceвЂќ repair and or replacement of the AD-4в„ў air dryer. The portion of the manual that follows is concerned with installing an AD-4в„ў air dryer on a vehicle not previously equipped with one. VEHICLE APPLICATION REQUIREMENTS The basic application requirements presented here apply to a standard air dryer installation. The majority of highway vehicles in use today will meet these basic requirements however, some may not. Examples of vehicles that may not meet the requirements include bulk trailer unloading operations and other high air consumption/continuous flow systems. While the AD-4в„ў air dryer can be used on these vehicles the standard installation procedure presented in this manual may require modification to assure proper operation and service life. Consult your local authorized Bendix parts outlet or sales representative for additional information. 1. Charge Cycle Time - The AD-4в„ў air dryer is designed to provide clean, dry air for the brake system. When a vehicleвЂ™s air system is used to operate non-brake air accessories it is necessary to determine that during normal, daily operation the compressor should recover from governor вЂњcut-inвЂќ to governor вЂњcut-outвЂќ (usually 100 psi to 120 psi) in 90 seconds or less at engine RPMs commensurate with the vehicle vocation. If the recovery time consistently exceeds this limit, it may be necessary to вЂњbypassвЂќ the air accessory responsible for the high air usage. Consult your local authorized Bendix parts outlet or sales representative for additional information. 2. Purge Cycle Time - During normal vehicle operation, the air compressor must remain unloaded for a minimum of 20 seconds for the standard AD-4в„ў air dryer or 30 seconds for the extended purge model. These minimum purge times are required to ensure complete regeneration of the desiccant material. If the purge time is occasionally shorter than the times specified, no permanent ill effect should be expected, however, if the purge time is consistently less than the minimum, an accessory by-pass system must be installed. 3. European Air Brake Systems - Brake systems that incorporate compressors without integral unloading mechanisms and/or utilize a compressor discharge line unloader valve have special AD-4в„ў air dryer installation requirements. Consult your local authorized Bendix parts outlet or sales representative for additional information. 4. Air Compressor Size - Although the AD-4в„ў air dryer can be used in conjunction with larger compressors, it was designed primarily for units rated for up to 17 CFM. It is recommended that when using the AD-4в„ў air dryer with a compressor which has a rated displacement exceeding 17 CFM that an authorized Bendix parts outlet or Bendix marketing representative be contacted for assistance. 5. Holset вЂњE or QEвЂќ Type Air Compressors - In order for the AD-4в„ў air dryer to function properly when installed with the Holset Type вЂњE or QEвЂќ compressor, several specialized Holset components are required. Consult your local authorized Holset parts outlet or sales representative for additional information. 6. Use of Standard or Extended Purge AD-4в„ў Air Dryer Use the following guidelines: Total Vehicle Reservoir Volume Requirement Less than 9,000 cu. in. ................... Standard AD-4в„ў Air Dryer 9,000 - 12,500 cu. in. ............................ Extended Purge AD-4в„ў Air Dryer Greater than 12,500 cu. in. ............. Contact Bendix Rep. or Bendix Engineering 11 VEHICLE PREPARATION 1. Park the vehicle on a level surface and prevent movement by means other than the brakes. 2. Drain all reservoirs to 0 p.s.i. (0 kPa). LOCATING AD-4в„ў AIR DRYER ON VEHICLE 1. The AD-4в„ў air dryer must be mounted vertically (purge exhaust toward road surface) outside the engine compartment in an area of air flow while the vehicle is in motion. The AD-4в„ў air dryer must not be exposed to direct wheel splash (located behind axle mud flap is acceptable). 2. Locate the AD-4в„ў air dryer as close to the first (supply) reservoir as possible. 3. Do not locate the AD-4в„ў air dryer near heat producing components such as the vehicle exhaust and make certain adequate clearance from moving components (e.g. drive shaft, suspension, pitman arm, etc.) is provided. 4. Locate the AD-4в„ў air dryer on vehicle so that a minimum of 11 inches (28 cm) clearance below the end cover is available to allow servicing. Alternatively, provide access to the bracket bolts so the unit may be removed for servicing. 5. When choosing the mounting location for the AD-4в„ў air dryer, note the discharge line length requirements stated under the heading Connecting the Air Lines, elsewhere in this instruction sheet. Important Note: Under normal operating conditions, the maximum inlet air temperature for the AD-4в„ў air dryer is 160 degrees Fahrenheit. MOUNTING THE AD-4в„ў AIR DRYER 1. Assemble the mounting strap and mounting bracket as illustrated in Figures 5 & 6 using the 5/16" screws, nuts and lock washers. Make certain the mounting bracket hook is installed on the 5/16" screw of the lower mounting bracket and that it engages the AD-4в„ў air dryer end cover. Make certain that the inside surface of the top mounting strap bears entirely on the cylindrical surface of the dryer shell and that it does not overlap the domed top. The brackets should be a minimum of 5.5 inches apart. After positioning the mounting straps according to the installation requirements, torque both 5/16" screws to 80-120 inch pounds. Note: The mounting bracket at the base of the AD-4в„ў air dryer can be of two types. The one described above or a single piece right angle bracket. (See Figure 7.) To install the single piece lower mounting bracket, remove and discard two of the bolts and nuts that retain the end cover. Install the lower mounting bracket as shown in Figure 7. Utilizing the bolts and lock nuts provided with 12 the bracket and placing the washers removed in proper sequence, torque to 270-330 inch pounds. To determine which end cover bolts to utilize to attach the bracket, take into consideration the piping connections required to install the AD-4в„ў air dryer and use those that will best position the unit for ease of installation. 2. A universal mounting plate (Pc. No. 248478) is available to facilitate the mounting of the AD-4в„ў air dryer. It is not included in kits but can be obtained through an authorized Bendix parts outlet. 3. Use 3/8" bolts (grade 5 min.) and washers (not furnished) to mount the AD-4в„ў air dryer to the vehicle. Torque to 25 ft. Ibs. (300 inch pounds). CONNECTING THE AIR LINES PURGE CONTROL LINE 1. Install a purge control air line having a minimum inside diameter of 3/16 inches between the AD-4в„ў air dryer end cover control port and an unused unloader port on the governor. The control line must be plumbed direct to the governor and not in series with automatic drain valves, lubrication systems, etc. 2. The control line should slope downward to the end cover without forming potential water traps. DISCHARGE LINE General: Refer to Appendix A, Table A for recommended discharge line lengths and sizes for various vehicle applications and vocations. PURGE EXHAUST LINE 1. If it is necessary to direct AD-4в„ў air dryer discharge contaminants away from vehicle components a 1.5 inch (38.1 mm) I.D. hose can be clamped on the AD-4в„ў air dryer exhaust cover. WIRING THE HEATER/THERMOSTAT 1. Note the required voltage and wattage for the AD-4в„ў air dryer heater by checking the end cover as shown in Figure 8. 2. Remove the rubber boot covering the single electrical terminal of the standard AD-4в„ў air dryer end cover. Install a 16 gauge wire between the вЂњonвЂќ position of the vehicle ignition or engine вЂњkillвЂќ switch and the heater/thermostat electrical terminal. An 8-10 amp fuse is required in this line regardless of voltage. 3. For AD-4в„ў air dryer end covers with a dual terminal (See Figure 6) heater connections, the power and insulated return wires may be connected to either terminal. An 8-10 amp fuse should be installed in the power carrying wire. Use 16 gauge wire for both power and return. 4. All electrical connections must be waterproofed. 5. Tie wrap or support all electrical wire leading to the AD-4в„ў air dryer at 6 - 8 inch intervals. Note: Wires should have sufficient slack and not be completely taught. TESTING THE AD-4в„ў AIR DRYER Before placing the vehicle in service, perform the following tests: 1. Close all reservoir drain cocks. 2. Build up system pressure to governor cut-out and note that the AD-4в„ў air dryer purges with an audible escape of air. 3. вЂњFanвЂќ the service brakes to reduce system air pressure to governor cut-in. Note that the system once again builds to full pressure and is followed by a purge at the AD-4в„ў air dryer exhaust. 4. It is recommended that the following items be tested for leakage to assure that the AD-4в„ў air dryer will not cycle excessively. (A) Total air system leakage (See Bendix publication BW-5057 вЂњAir Brake HandbookвЂќ). (B) Compressor unloader mechanism. (C) Governor. (D) Drain cock and safety valve in first (supply) reservoir. (E) All air connections leading to and from the first (supply) reservoir. 13 AD-4в„ў AIR DRYER TROUBLESHOOTING CHART SYMPTOMS 1. Dryer is constantly вЂњcyclingвЂќ or purging. Dryer purges frequently (every 4 minutes or less while vehicle is idling). CAUSE A. Excessive system leakage. IMPORTANT: Note whether air pressure loss is shown on dash gauge(s). Pressure loss shown on gauges is caused by service brake system or component leakage. Pressure loss NOT SHOWN on gauges is caused by supply system or component leakage. REMEDY A. If leakage IS SHOWN on gauges test for excessive service brake system leakage. Allowable leakage: Single vehicle - 1 psi/minute either service reservoir. Tractor trailer - 3 psi/minute either service reservoir. Repair and retest as required. B. If leakage is NOT SHOWN on gauges test for excessive supply system leakage. Remove drain cock or valve in supply reservoir (wet tank) and install air gauge. Build system pressure, allow air dryer to purge and observe air gauge in supply reservoir. Pressure drop should not exceed 1 psi per minute. Perform tests 1 to 6 in the order presented. 14 AD-4в„ў AIR DRYER TROUBLESHOOTING CHART (Continued) SYMPTOMS CAUSE REMEDY 1. Test fittings, hoses, lines and connections. Apply soap solution to detect excessive leakage. Tighten or replace as needed then repeat the air dryer charge-purge cycle and observe the gauge installed in the supply reservoir. If leakage is within limits remove gauge from reservoir and replace drain cock or valve. If excessive leakage is detected, continue testing. 2. Test accessories connected to supply reservoir. Drain all air pressure from system, disconnect all air lines leading to accessories (fan clutch, wipers, air seats, etc.) and plug the reservoir at disconnection point. Build air system pressure until air dryer purges and observe supply reservoir gauge. If leakage is no longer excessive, repair or replace leaking accessory. If excessive leakage is detected, continue testing. 3. Test governor leakage. Build system pressure to governor cut-out, turn off engine and apply soap solution to governor exhaust port and around cap. Leakage should not exceed a 1" bubble in 5 seconds. Reduce system pressure to 80 psi or less, and re-apply soap solution. Leakage should not exceed a 1" bubble in 5 seconds. If excessive leakage is detected in either test, repair or replace governor. 4. Test compressor unloader leakage. Drain all air pressure from system and remove the governor from the compressor. Temporarily plug the governor unloader port or air line that mated with, or connected to, the compressor. Build air system pressure until air dryer purges then IMMEDIATELY SHUT OFF THE ENGINE. Observe the air gauge in the supply reservoir. If leakage is within limits, replace the compressor unloaders. Re-connect the governor to the compressor (after removing plug installed in governor) and retest while observing supply reservoir gauge. If excessive leakage is detected, continue testing. 5. Test air dryer purge valve and outlet (delivery) check valve. Drain all air pressure from system, remove the control line connection at the air dryer and plug the end of the air line leading to the governor (not the air dryer control port). Build system pressure to governor cut-out and observe air gauge. If little or no pressure drop is observed replace the air dryer check valve. If pressure drop continues apply soap solution to air dryer purge exhaust and purge control port (where the control line was removed). Leakage should not exceed a 1" bubble in 5 seconds. If leakage is excessive repair or replace purge valve assembly. 15 AD-4в„ў AIR DRYER TROUBLESHOOTING CHART (Continued) SYMPTOMS CAUSE REMEDY 6. With gauge installed at RES port of governor, pressure should not drop below вЂќCut-InвЂќ pressure at the onset of the compressor вЂњUnloadedвЂќ cycle. If pressure drops, check for вЂњkinksвЂќ or restrictions in line connected to RES port. Line connected to RES port on governor must be same diameter, or preferably larger than, lines connected to UNL port(s) on governor. B. Leaking purge valve in air dryer end cover (control side). B. Remove end cover. Apply 120 psi at control port. Soap both sides around purge valve to test for control piston leakage. Leakage should not exceed a 1" bubble in less than 5 seconds. C. Holset вЂњEвЂќ type compressor. C. Test the Holset E Compressor unloader system with feedback line and check valve for proper operation. Make certain Holset ECON is not used with the drop-in version of the air dryer, if so, remove and retest. When installing a Bendix Drop-In air dryer in a system equipped with a Holset E or QE compressor, remove the Holset ECON valve along with its feed back and governor control line. 2. Water and/or Oil in Supply or Service Reservoir. 16 A. Improper discharge line length or improper line material. Maximum air dryer inlet temperature is exceeded. A. Refer to section entitled Connecting the Air Lines as well as Appendix A, Table A columns 1 & 2 then and check line size and length. B. Air system charged from outside air source (outside air not passing through air dryer). B. If system must have outside air fill provision, outside air should pass through air dryer. This practice should be minimized. AD-4в„ў AIR DRYER TROUBLESHOOTING CHART (Continued) SYMPTOMS 2. Water and/or Oil in Supply or Service Reservoir (continued). CAUSE REMEDY C. Air dryer not purging (see Symptom #5). C. See Symptom #5. D. Purge (air exhaust) time insufficient due to excessive system leakage (see causes for Symptom #1). D. Check causes and remedies for Symptom #1. E. Excessive air usage, duty cycle too high - Air dryer not compatible with vehicle air system requirement (Improper air dryer/vehicle application). E. See Appendix A, Table A, column 1, for recommended compressor sizes. If the compressor is вЂњtoo smallвЂќ for the vehicle vocation (for example, where a vehicleвЂ™s vocation has changed or service conditions exceed the original vehicle or engine OE specвЂ™s) then upgrade the compressor. Note: The costs incurred (e.g. installing a larger capacity compressor, etc.) are not covered under original compressor warranty. NOTE: Duty Cycle is the ratio of time the compressor spends building air to total engine running time. Air compressors are designed to build air (run вЂњloadedвЂќ) up to 25% of the time. Higher duty cycles cause conditions that affect air brake charging system performance which may require additional maintenance. Factors that add to the duty cycle are: air suspension, additional air accessories, use of an undersized compressor, frequent stops, excessive leakage from fittings, connections, lines, chambers or valves, etc. Charge Cycle Time - The AD-4в„ў air dryer is designed to provide clean, dry air for the brake system. When a vehicleвЂ™s air system is used to operate non-brake air accessories it is necessary to determine that; during normal, daily operation the compressor should recover from governor вЂњcut-inвЂќ to governor вЂњcut-outвЂќ (usually 100 psi to 120 psi) in 90 seconds or less at engine RPMвЂ™s commensurate with the vehicle vocation. If the recovery time consistently exceeds this limit, it may be necessary to вЂњbypassвЂќ the air accessory responsible for the high air usage. An example of where a by-pass system would be required is when the compressor is used to pressurize a tank trailer for purposes of off-loading product. Consult your local authorized Bendix parts outlet or sales representative for additional information. Purge Cycle Time - During normal vehicle operation, the air compressor must remain unloaded for a minimum of 30 seconds. This minimum purge time is required to ensure complete regeneration of the desiccant material. If the purge time is consistently less than the minimum, an accessory by-pass system must be installed. Consult your local authorized Bendix parts outlet or sales representative for additional information. Air Compressor Size - Although the AD-4в„ў air dryer can be used in conjunction with larger compressors, it was designed primarily for units rated for up to 30 CFM. It is recommended that when using the AD-4в„ў air dryer with a compressor which has a rated displacement exceeding 30 CFM that an authorized Bendix parts outlet or Bendix marketing representative be contacted for assistance. 17 AD-4в„ў AIR DRYER TROUBLESHOOTING CHART (Continued) SYMPTOMS 2. Water and/or Oil in Supply or Service Reservoir (continued). CAUSE F. Air compressor discharge and/or air dryer inlet temperature too high. REMEDY F. Restricted discharge line. See Appendix A, Table A, column 1 & 2 for recommended sizes. If discharge line is restricted or more than 1/16" carbon build up is found, replace the discharge line. Replace as necessary. Discharge Line Freeze-Up The discharge line must maintain a constant slope down from the compressor to the air dryer inlet fitting to avoid low points where ice may form and block the flow. If, instead, ice blockages occur at the air dryer inlet, insulation may be added here, or if the inlet fitting is a typical 90 degree fitting, it may be changed to a straight or 45 degree fitting. For more information on how to help prevent discharge line freeze-ups, see Bendix Bulletins TCH-08-21 and TCH-08-22. Shorter discharge line lengths or insulation may be required in cold climates. Insufficient coolant flow through compressor. Inspect coolant line. Replace as necessary (I.D. is 1/2" min.). Inspect the coolant lines for kinks and restrictions and fittings for restrictions. Replace as necessary. Verify coolant lines go from engine block to compressor and back to the water pump. Repair as necessary. Restricted air inlet (not enough air to compressor). Check compressor air inlet line for restrictions, brittleness, soft or sagging hose conditions etc. Repair as necessary. Inlet line size is 3/4 ID. Maximum restriction requirement for compressors is 25 inches of water. Check the engine air filter and service if necessary (if possible, check the air filter usage indicator). Poorly filtered inlet air (poor air quality to compressor). Check for leaking, damaged or malfunctioning compressor air inlet components (e.g. induction line, fittings, gaskets, filter bodies, etc.). Repair inlet components as needed. Note: Dirt ingestion will damage compressor and is not covered under warranty. If you found excessive oil present in the service reservoir and you did not find any issues above, the compressor may be passing oil. Replace compressor. If still under warranty, follow normal warranty process. G. Compressor malfunction. G. If you found excessive oil present in the service reservoir and you did not find any issues above, the compressor may be passing oil. Test the compressor using the BASIC cup method as described in the Bendix compressor service manual and referred to in Appendix A, Table A, column 5. Replace compressor. If still under warranty, follow normal warranty process. 18 AD-4в„ў AIR DRYER TROUBLESHOOTING CHART (Continued) CAUSE REMEDY H. Air by-passes desiccant cartridge assembly. H. If vehicle uses Holset compressor, inspect feedback check valve for proper installation and operation. SYMPTOMS When replacing the desiccant cartridge, make sure desiccant cartridge assembly is properly installed and sealing rings are in place on mounting surface of desiccant cartridge. I. Desiccant requires replacement. I. Replace desiccant cartridge assembly. Refer to Appendix A, Table A columns 3 & 4 for recommended intervals. 3. Oil present at air dryer purge exhaust or cartridge during maintenance. A. Air brake charging system is functioning normally. A. Air dryers remove water and oil from the air brake charging system. A small amount of oil is normal. Check that regular maintenance is being performed and that the amount of oil in the air tanks (reservoirs) is within the acceptable range shown on the BASIC cup (see also column 5 of Appendix A, Table A). Replace the air dryer cartridge as needed and return the vehicle to service. 4. Safety valve on air dryer вЂњpopping offвЂќ or exhausting air. A. Restriction between air dryer and supply (first) reservoir. A. Check to determine if air is reaching supply reservoir. Inspect for kinked tubing or hose. Check for undrilled or restricted hose or tubing fittings and repair or replace as needed. B. Air dryer safety valve malfunction. B. Verify relief pressure is at vehicle or component manufacturer specifications. Replace if malfunctioning. C. Desiccant cartridge maintenance required. C. Refer to Appendix A Table A and column 3. Check compressor for excessive oil passing and/or correct compressor installation. Repair or replace as necessary. Replace desiccant cartridge. D. Malfunctioning discharge check valve in end cover of the AD-4в„ў air dryer. D. Test to determine if air is passing through check valve. Repair or replace. E. Excessive pressure pulsations from compressor. (Typical single cylinder type). E. Increase volume in discharge line by increasing length or diameter. Add a ping tank (small reservoir). 19 AD-4в„ў AIR DRYER TROUBLESHOOTING CHART (Continued) SYMPTOMS 5. Constant exhaust of air at air dryer purge valve exhaust. (Charge mode.) 6. Can not build system air pressure. 7. Air dryer does not purge or exhaust air. 20 CAUSE REMEDY F. Governor malfunction. Missing or restricted governor control line installation. F. Test governor operation and/or inspect the control line leading from the governor UNL (unloader) port to the air dryer control port. A. Air dryer purge valve leaking excessively. A. With compressor loaded, apply soap solution on purge valve exhaust, to test for excessive leakage. Repair purge valve as necessary. B. Compressor fails to unload (stop compressing air) and air dryer purge exhaust makes вЂњsputteringвЂќ or вЂњpoppingвЂќ sound. B. Confirm failure to unload by increasing & decreasing engine RPM and noting change in the rate of leakage and intensity of accompanying leakage sound. Repair/replace compressor unloaders. C. Purge control line connected to reservoir or exhaust port of governor. C. Purge control line must be connected to unloader port of governor. D. Purge valve frozen open malfunctioning heater and thermostat, wiring, blown fuse. D. Test heater and thermostat as described in Preventative Maintenance Section. E. Excessive system leakage. E. See Symptom #1. F. Purge valve stays open supply air leaks to control side. F. Repair purge valve and housing. A. Inlet and outlet air connections reversed. A. Connect compressor discharge to air dryer supply port. Reconnect lines properly. B. Check valve between air dryer and first reservoir. B. Test check valve for proper operation. Repair or replace as necessary. C. Kinked or blocked (plugged) discharge line. C. Check to determine if air passes through discharge line. Check for kinks, bends, excessive carbon deposits, or ice blockage. D. Excessive bends in discharge line (water collects and freezes). D. Discharge line should be constantly sloping from compressor to air dryer with as few bends as possible. E. Refer to Symptom 4, causes E & F. E. Refer to Symptom #4, Remedies E & F. A. Missing, broken, kinked, frozen, plugged or disconnected purge control line. A. Inspect control line from governor UNL (unloader) port to control port of air dryer. Test to determine air flows through purge control line when compressor unloaded. Check for undrilled fittings. (See Symptom #4, Remedy C.) B. Faulty air dryer purge valve. B. After determining air reaches purge valve (Remedy A above), repair purge valve. C. See Causes, B, E, G for Symptom #4. C. Refer to Remedies B, E, G for Symptom #4. AD-4в„ў AIR DRYER TROUBLESHOOTING CHART (Continued) SYMPTOMS CAUSE REMEDY 8. Desiccant material being expelled from air dryer purge valve exhaust (may look like whitish liquid or paste or small beads.) A. This symptom is almost always accompanied by one or more of Symptoms 1, 2, 3, 4 and 5. See related causes for these Symptoms above. A. See Causes and Remedies for Symptoms 1, 2, 3, 4 and 5. B. Air dryer not securely mounted. (Excessive vibration.) B. Vibration should be held to minimum. Add bracket supports or change air dryer mounting location if necessary. C. Malfunctioning or saturated desiccant cartridge. C. Replace desiccant cartridge assembly. D. Compressor passing excessive oil. E. Desiccant cartridge not assembled properly to end cover. (Loose attachment) D. Check for proper compressor installation; if symptoms persist, replace compressor. A. Single cylinder compressor with high pulse cycles. A. A slight вЂњpingingвЂќ sound may be heard during system build up when a single cylinder compressor is used. If this sound is deemed objectionable, it can be reduced substantially by increasing the discharge line volume. - OR Unsatisfactory desiccant life. 9. вЂњPingingвЂќ noise excessive during compressor loaded cycle. E. Check the torque on the desiccant cartridge to end cover attachment. Refer to assembly section of this data sheet. This can be accomplished by adding an additional four feet of discharge line or adding a 90 cubic inch reservoir between the compressor and the AD-4в„ў air dryer. IMPORTANT: Do not exceed the line lengths requirements specified in this manual. 10. Constant seepage of air at air dryer purge valve exhaust (non-charging mode.) 11. The air dryer purge piston cycles rapidly in the compressor unloaded (noncompressing) mode. A. Defective check valve assembly in AD-4в„ў air dryer end cover. A. Refer to Remedy C, Symptom #1. B. Leaking Turbo Cutoff valve. B. Repair or replace purge valve assembly. C. Leaking purge valve control piston o-ring. C. Repair or replace purge valve assembly. A. Compressor fails to вЂњunloadвЂќ. A. Faulty governor installation; no air line from governor to compressor or line is kinked or restricted. Install or repair air line. 21 Appendix A Table A: Maintenance Schedule and Usage Guidelines Regularly scheduled maintenance is the single most important factor in maintaining the air brake charging system. Column 1 Vehicle Used for: Typical Compressors No. of Spec'd Axles Column 2 Discharge Line I.D. Length 1/2 in. 6 ft. Column 3 Recommended Air Dryer Cartridge Replacement 1 Column 4 Recommended Reservoir Drain Schedule2 Column 5 Acceptable Reservoir Oil Contents3 at Regular Drain Interval Compressor with up to 25% duty cycle e.g. Line haul single trailer with air suspension, school bus. 5 or less High Air Use e.g. Double/triple trailer, open highway coach/RV, (most) pick-up & delivery, yard or terminal jockey, off-highway, construction, loggers, concrete mixer, dump truck, fire truck. 8 or less Compressor with up to 25% duty cycle e.g. City transit bus, refuse, bulk unloaders, low boys, urban region coach, central tire inflation. 22 12 or less BendixВ® Tu-FloВ® 750 air compressor Compressor with up to 25% duty cycle For oil carry-over control4 suggested upgrades: 5/8 in. 9 ft. Every 3 Years 1/2 in. 9 ft. For oil carry-over control4 suggested upgrades: 5/8 in. 1/2 in. 5/8 in. Recommended Every Month Max of every 90 days 12 ft. For the BASIC Test Kit: Order Bendix P/N 5013711 Every 2 Years 15 ft. Every Month 5/8 in. 12 ft. For oil carry-over control4 suggested upgrades: 3/4 in. BASIC test acceptable range: 3 oil units per month. See appendix A. 12 ft. For oil carry-over control4 suggested upgrades: BendixВ® BA-922в„ў, or DuraFloв„ў 596 air compressor e.g. Line haul single trailer w/o air suspension, air over hydraulic brakes. 5 or less BendixВ® BA-921в„ў air compressor Compressor with less than 15% duty cycle BendixВ® Tu-FloВ® 550 air compressor Low Air Use BASIC test acceptable range: 5 oil units per month. See appendix A. Every Year 15 ft. Footnotes: 1 With increased air demand the air dryer cartridge needs to be replaced more often. 2 Use the drain valves to slowly drain all reservoirs to zero psi. 3 Allow the oil/water mixture to fully settle before measuring oil quantity. 4 To counter above normal temperatures at the air dryer inlet, (and resultant oil-vapor passing upstream in the air system) replace the discharge line with one of a larger diameter and/or longer length. This helps reduce the air's temperature. If sufficient cooling occurs, the oilvapor condenses and can be removed by the air dryer. Discharge line upgrades are not covered under warranty. Note: To help prevent discharge line freeze-ups, shorter discharge line lengths or insulation may be required in cold climates. (See Bendix Bulletins TCH-08-21 and TCH-08-22, included in Appendix B, for more information.) 5 For certain vehicles/applications, where turbo-charged inlet air is used, a smaller size compressor may be permissible. Note: Compressor and/or air dryer upgrades are recommended in cases where duty cycle is greater than the normal range (for the examples above). For BendixВ® Tu-FloВ® 550 and 750 compressors, unloader service is recommended every 250,000 miles. Appendix B Additional Troubleshooting Information The troubleshooting procedure presented on the following pages has been excerpted from a laminated card entitled: Troubleshooting Charging and Air Supply Systems. The complete card can be obtained from authorized Bendix parts outlets under literature number BW1779. It is presented here because of the air dryers connection to the supply air system and for convenience. The procedure is not all inclusive but rather represents the most commonly encountered complaints. STANDARD SINGLE CHECK VALVE (USED W/INTEGRAL PURGE AIR DRYERS) GOVERNOR LOW PRESSURE INDICATOR DASH GAUGE CONVENTIONAL SUPPLY SYSTEM & INTEGRAL PURGE AIR DRYER REAR SAFETY VALVE SUPPLY TWO CYL. COMPRESSOR AIR DRYER FRONT STANDARD SINGLE CHECK VALVE SAFETY VALVE GOVERNOR HOLSET TYPE "E & QE" COMPRESSOR WITH ECON VALVE AIR DRYER REAR LOW PRESSURE INDICATOR SUPPLY HOLSET вЂњE OR QEвЂќ COMPRESSOR FRONT HOLSET ECON VALVE SPECIAL SINGLE CHECK ("CHOKE" IN INLET) STANDARD SINGLE CHECK VALVE SAFETY VALVE GOVERNOR HOLSET TYPE "E & QE" COMPRESSOR W/O ECON VALVE DASH GAUGE AIR DRYER DRAIN COCK LOW PRESSURE INDICATOR REAR DASH GAUGE SUPPLY HOLSET вЂњE OR QEвЂќ COMPRESSOR SPECIAL SINGLE CHECK ("CHOKE" IN INLET) SINGLE CHECK PROTECTION VALVE (USED W/SYSTEM PURGE AIR DRYERS) FRONT SINGLE CHECK VALVE (USED W/INTEGRAL PURGE AIR DRYERS) 23 24 BW1450 В© 2004 Bendix Commercial Vehicle Systems LLC All rights reserved. 10/2004 Printed in U.S.A.
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