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:
DESICCANT BED OIL SEPARATOR CONTROL PORT

HOUSING LOWER BRACKET

CHECK DISCHARGE VALVE LINE ASSEMBLY
SUPPLY PORT CHECK VALVE ASSEMBLY PURGE VALVE HOUSING ASSEMBLY PURGE VALVE DISCHARGE PORT
FIGURE 5 - AD-9 AIR DRYER SECTIONAL VIEW
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

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. Every 10,800 hours; 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.
AD-9 AIR DRYER LOWER MOUNTING BRACKET

AD-9 END COVER

FEMALE CONNECTOR MALE CONNECTOR LATCH MUST BE INSERTED UNTIL IT SNAPS OVER TAB ON MATING CONNECTOR

SIDE VIEW

END VIEW

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.
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 #1 reservoir. A rapid loss of pressure could indicate a failed outlet port check valve. This can be confirmed by bleeding the system down, removing the check valve assembly from the end cover, subject air pressure to the unit and apply a soap solution to the check valve side. 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-9 air dryer purges with an audible escape of air. Fan 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-9 air dryer purge.

A two lead, 12 inch, wire harness with attached weather resistant connector is supplied with all retrofit and replacement AD-9 air dryers. Connect one of the two leads of the wire harness to the engine kill or ignition switch. The remaining lead of the wire harness must be connected to a good vehicle ground. A fuse should be installed in the power carrying wire; install a 10 amp fuse for 12 volt heaters and a 5 amp fuse for a 24 volt heater. Use 14 AWG wire if it is necessary to lengthen the wire harness provided. Make certain all wire splices are waterproofed. Tie wrap or support all electrical wire leading to the AD-9 air dryer.
FIGURE 6 - HEATER AND THERMOSTAT CONNECTOR
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 re-seat when the stem is released. 5. Check all lines and fittings leading to and from the air dryer for leakage and integrity. 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 voltage to the heater and thermostat assembly using a voltmeter or test light. Unplug the electrical connector at the air dryer and place the test leads on each of the pins of the male connector. If there is no voltage, look for a blown fuse, broken wires, or corrosion in the vehicle wiring harness. Check to see if a good ground path exists.
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 pins in the female connector. The resistance should be 1.5 to 3.0 ohms for the 12 volt heater assembly and 6.8 to 9.0 ohms for the 24 volt heater assembly. Note: Some early models of the AD-9 air dryer will have resistance readings of 1.0 to 2.5 ohms for the 12 volt heater assembly and 4.8 to 7.2 ohms for the 24 volt heater assembly. If the resistance is higher than the maximum stated, replace the purge valve housing assembly, which includes the heater and thermostat assembly. Warm the end cover assembly to over 90 degrees Fahrenheit and again check the resistance. The resistance should exceed 1000 ohms. 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, replace the purge valve housing assembly, which includes the heater and thermostat assembly.

800405

5004341

5004479

5004342

107695

Service New Purge Valve Housing Assembly Soft Seat (w/heater and thermo.) 12 volt system. Remanufactured Exchange Purge Valve Housing Assembly - Soft Seat (w/heater and thermo.) 12 volt system. Service New Purge Valve Housing Assembly Hard Seat (w/heater and thermo.) 12 volt system. Service New Purge Valve Housing Assembly DLU (w/heater and thermo.) 12 volt system. Service New Purge Valve Housing Assembly - Soft Seat (w/heater and thermo.) 24 volt system. Remanufactured Exchange Purge Valve Housing Assembly - Soft Seat (w/heater and thermo.) 24 volt system. Service New Valve Housing Assembly - Hard Seat (w/heater and thermo.) 24 volt system. Service New Purge Valve Housing Assembly - DLU (w/heater and thermo.) 24 volt system. Complete Mounting Bracket Kit This kit contains the upper and lower brackets as well as the necessary hardware items to mount them.

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 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. 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 vehicles 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-IS air dryer system or a dryer reservoir module, be sure to drain the purge reservoir.
REBUILDING THE AD-9 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-9 air dryer desiccant cartridge assembly, it is recommended that the air dryer be removed from the vehicle.
MAINTENANCE KITS AVAILABLE:
5005037 Hard Seat Purge Valve Housing Maintenance Kit 5005893 Soft Seat Purge Valve Housing Maintenance Kit These kits contain the parts necessary to rebuild the air portion of the purge valve housing and do not include the heater and thermostat. 107796 Remanufactured Desiccant Cartridge Replacement Kit This kit contains the parts necessary to change the desiccant cartridge only. 107794 Desiccant Cartridge Replacement Kit This kit contains the parts necessary to change the desiccant cartridge only. 107799 End Cover Check Valve Assembly Replacement 3/4 inch thread size. 107800 End Cover Check Valve Assembly Replacement 1/2 inch thread size.

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 and the purge valve housing 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 seats 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 the lubricant included in the maintenance kit. Refer to Figure 7 during assembly unless otherwise advised. 1. Purge Valve Housing Assembly A. Install the quad-ring (14) in its groove on the O.D. of the purge piston (10). Place the return spring (13) in
FIGURE 8 - END COVER TO HOUSING TORQUE PATTERN 9 1&8 3
3. Install the desiccant cartridge o-ring (21) in its groove in the end cover. Using a light coat of lubricant (included in kit), lubricate the bottom of the desiccant cartridge in the area that will contact the o-ring (21) and end cover. Screw the desiccant cartridge into the end cover until contact is made between it and the o-ring. Using a strap or chain wrench positioned 2-3" from the bottom of the cartridge, turn the desiccant cartridge clockwise 180225 degrees beyond the position where initial contact was made between the cartridge and end cover o-ring. Torque should not exceed 50 ft. Ibs. 4. Install the end cover outer housing o-ring (23) on the shoulder in the end cover. Place the housing (24) over the desiccant cartridge and align the holes. Install the six 3/8" cap screws (16), lock nuts (19) and twelve special washers (17) making certain they are in the proper position as marked during disassembly. The two longer 3/8" cap screws (18) will be used to secure the AD-9 air dryer to its mounting bracket. Tighten the six cap screws and nuts in a star pattern in a fashion similar to Figure 8; depending on lower bracket location. Torque to 270-385 in. Ibs. (Refer to Fig. 8.) Note: The two remaining bolt holes in the end cover and two 3/8" cap screws must be the ones marked during disassembly to assure proper orientation of the ports and adequate length of the cap screws.

RETROFITTING THE AD-9 AIR DRYER
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-9 air dryer should be followed in lieu of those presented here. The preceding portion of this manual deals with in-service repair and/or replacement of the AD-9 air dryer. The portion of the manual that follows is concerned with installing an AD-9 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-9 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-9 air dryer is designed to provide clean, dry air for the brake system. When a vehicles 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 cut-in to governor cut-out (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 bypass 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-9 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

INSTALLATION

1. Install the assembled AD-9 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 the air dryer. The AD-9 air dryer end cover should rest on the bracket. Using the remaining two 3/ 8" cap screws (18), four special washers (17), and two lock nuts (19), secure the air dryer to the lower bracket. Tighten, then torque the two remaining cap screws to 270-385 in. Ibs. 2. Tighten the 5/16" X 4-1/2" hex cap screw (25) and nut (28) on the upper mounting bracket saddle (27) and strap (26). Torque to 80-120 in. Ibs. 3. Reconnect the three air lines to the proper ports on the end cover (identified during disassembly). 4. Reconnect the vehicle wiring harness to the AD-9 air dryer heater and thermostat assembly connector by plugging it into the air dryer connector until its lock tab snaps in place. 5. Before placing vehicle back into service, perform the Operation and Leakage Tests stated elsewhere in this manual.
mechanisms and/or utilize a compressor discharge line unloader valve have special AD-9 air dryer installation requirements. Consult your local authorized Bendix parts outlet or sales representative for additional information. 4. Air Compressor Size - Although the AD-9 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-9 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 E or QE Type Air Compressors - In order for the AD-9 air dryer to function properly when installed with the Holset Type E or QE 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-9 Air Dryer Use the following guidelines: Total Vehicle Reservoir Volume
LOCATING AD-9 AIR DRYER ON VEHICLE
1. The AD-9 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-9 air dryer must not be exposed to direct wheel splash (located behind axle mud flap is acceptable). 2. Locate the AD-9 air dryer as close to the first (supply) reservoir as possible. 3. Do not locate the AD-9 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-9 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-9 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-9 air dryer is 160 degrees Fahrenheit.

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.
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 reapply 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. Reconnect 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
SYMPTOMS CAUSE REMEDY 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. 6. With gauge installed at RES port of governor, pressure should not drop below Cut-In pressure at the onset of the compressor Unloaded cycle. If pressure drops, check for kinks 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 housing assembly and/or o-rings in AD-9 air dryer end cover. C. Holset E type compressor. B. With the supply port open to atmosphere, apply 120 psi at the control port. Apply a soap solution to the supply port and exhaust port (purge valve seat area). Permissible leakage - 1" bubble in 5 seconds. C. Test the Holset E Compressor unloader system with feedback line and check valve for proper operation. Make certain Holset ECON is not in use with the drop-in version of the air dryer, if so, remove and retest.

Check Valve

Feed Back Line Typical Drop-In Air Dryer End Cover
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.
SYMPTOMS 2. Water in vehicle reservoir. CAUSE A. Desiccant requires replacement - excessive contaminants in desiccant cartridge assembly. B. Improper discharge line length or improper line material. Maximum air dryer inlet temperature is exceeded. C. Air system charged from outside air source (outside air not passing through air dryer). D. Air dryer not purging (see Symptom #5). E. Purge (air exhaust) time insufficient due to excessive system leakage (see causes for Symptom #1). F. Excessive air usage, duty cycle too high - Air dryer not compatible with vehicle air system requirement (Improper air dryer/vehicle application). 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 loaded) 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. REMEDY A. Replace desiccant cartridge.
B. Refer to section entitled Connecting the Air Lines as well as Appendix A, Table A columns 1 & 2 then check line size and length.
C. If system must have outside air fill provision, outside air should pass through air dryer. This practice should be minimized. D. See Symptom #5. E. Check causes and remedies for Symptom #1.
F. See Appendix A, Table A, column 1, for recommended compressor sizes. If the compressor is too small for the vehicle vocation (for example, where a vehicles vocation has changed or service conditions exceed the original vehicle or engine OE specs) then upgrade the compressor. Note: The costs incurred (e.g. installing a larger capacity compressor, etc.) are not covered under original compressor warranty. Charge Cycle Time - The AD-9 air dryer is designed to provide clean, dry air for the brake system. When a vehicles 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 cut-in to governor cut-out (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 bypass 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.

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.
SYMPTOMS CAUSE J. Desiccant requires replacement. REMEDY J. Replace desiccant cartridge assembly. Refer to Appendix A, Table A columns 3 & 4 for recommended intervals. 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. 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. Verify relief pressure is at vehicle or component manufacturer specifications. Replace if malfunctioning. 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. Test to determine if air is passing through check valve. Repair or replace.
3. Oil present at air dryer purge exhaust or cartridge during maintenance.
A. Air brake charging system is functioning normally.
4. Safety valve on air dryer popping off or exhausting air.
A. Restriction between air dryer and supply (first) reservoir. B. Air dryer safety valve malfunction. C. Desiccant cartridge maintenance required.
D. Malfunctioning defective discharge check valve in end cover of the AD-9 air dryer. E. Excessive pressure pulsations from compressor. (Typical single cylinder type). F. Governor malfunction. Missing or restricted governor control line installation. 5. Constant exhaust of air at air dryer purge valve exhaust. (Charge mode.) A. Air dryer purge valve leaking excessively. B. Compressor fails to unload (stop compressing air) and air dryer purge exhaust makes sputtering or popping sound.

E. Increase volume in discharge line by increasing length or diameter. Add a ping tank (small reservoir). F. Test governor operation and/or inspect the control line leading from the governor UNL (unloader) port to the air dryer control port. A. With compressor loaded, apply soap solution on purge valve exhaust, to test for excessive leakage. Repair purge valve as necessary. 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.
AD-9 AIR DRYER TROUBLESHOOTING CHART (Continued)
SYMPTOMS CAUSE C. Purge control line connected to reservoir or exhaust port of governor. D. Purge valve frozen open malfunctioning heater and thermostat, wiring, blown fuse. E. Excessive system leakage. F. Purge valve stays open supply air leaks to control side. 6. Can not build system air pressure. A. Inlet and outlet air connections reversed. B. Check valve between air dryer and first reservoir. C. Kinked or blocked (plugged) discharge line. D. Excessive bends in discharge line (water collects and freezes). E. Refer to Symptom 4, Causes E & F. 7. Air dryer does not purge or exhaust air. A. Missing, broken, kinked, frozen, plugged or disconnected purge control line. B. Faulty air dryer purge valve. C. See Causes B, E, G for Symptom #4. 8. Desiccant material being expelled from air dryer purge valve exhaust (may look like whitish liquid or paste or small beads.) - OR Unsatisfactory desiccant life. 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. B. Air dryer not securely mounted. (Excessive vibration.) C. Malfunctioning or saturated desiccant cartridge. D. Compressor passing excessive oil. REMEDY C. Purge control line must be connected to unloader port of governor. D. Test heater and thermostat as described in Preventative Maintenance Section.
E. See Symptom #1. F. Repair purge valve and housing.
A. Connect compressor discharge to air dryer supply port. Reconnect lines properly. B. Test check valve for proper operation. Repair or replace as necessary. C. Check to determine if air passes through discharge line. Check for kinks, bends, excessive carbon deposits, or ice blockage. D. Discharge line should be constantly sloping from compressor to air dryer with as few bends as possible. E. Refer to Symptom #4, Remedies E & F. 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. After determining air reaches purge valve (Remedy A above), repair purge valve. C. See Causes, B, E, G for Symptom #4. A. See Causes and Remedies for Symptoms 1, 2, 3, 4 and 5.

B. Vibration should be held to minimum. Add bracket supports or change air dryer mounting location if necessary. C. Replace desiccant cartridge assembly.
D. Check for proper compressor installation; if symptoms persist, replace compressor.
SYMPTOMS CAUSE E. Desiccant cartridge not assembled properly to end cover. (Loose attachment) 9. Pinging noise excessive during compressor loaded cycle. A. Defective check valve assembly in AD-9 air dryer end cover. B. Leaking Turbo Cutoff valve. C. Leaking purge valve control piston o-ring. 10. Constant seepage of air at air dryer purge valve exhaust (non-charging mode.) A. Defective check valve assembly in AD-9 air dryer end cover. B. Leaking Turbo Cutoff valve. C. Leaking purge valve control piston o-ring. 11. The air dryer purge piston cycles rapidly in the compressor unloaded (noncompressing) mode. A. Compressor fails to unload. REMEDY E. Check the torque on the desiccant cartridge to end cover attachment. Refer to assembly section of this service data sheet. A. Refer to Remedy C, Symptom #1.
B. Repair or replace purge valve assembly. C. Repair or replace purge valve assembly. A. Refer to Remedy C, Symptom #1.
B. Repair or replace purge valve assembly. C. Repair or replace purge valve assembly. A. Faulty governor installation; no air line from governor to compressor or line is kinked or restricted. Install or repair air line.
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 Typical Compressors No. of Spec'd Axles Column 2 Discharge Line I.D. Length Column 3 Recommended Air Dryer Cartridge Replacement1 Column 4 Recommended Reservoir Drain Schedule2 Column 5 Acceptable Reservoir Oil Contents3 at Regular Drain Interval

Vehicle Used for:

Low Air Use
Compressor with less than 15% duty cycle

1/2 in.

Bendix Tu-Flo 550 air compressor
6 ft. Recommended Every Month Max of every 90 days
e.g. Line haul single trailer w/o air suspension, air over hydraulic brakes.

Compressor with up to 25% duty cycle

5 or less

For oil carry-over control4 suggested upgrades:

5/8 in. 1/2 in.

9 ft. 9 ft.

Every 3 Years

e.g. Line haul single trailer with air suspension, school bus.
Bendix BA-921 air compressor
BASIC test acceptable range: 3 oil units per month. See appendix A.

5/8 in.

12 ft.

High Air Use

Bendix Tu-Flo 750 air compressor
Bendix BA-922, or DuraFlo 596 air compressor
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.
For the BASIC Test Kit: Order Bendix P/N 5013711
12 ft. Every 2 Years BASIC test acceptable range: 5 oil units per month. See appendix A.

8 or less

15 ft.
Every Month 5/8 in. 12 ft. Every Year
e.g. City transit bus, refuse, bulk unloaders, low boys, urban region coach, central tire inflation.

12 or less

3/4 in.

Footnotes:

With increased air demand the air dryer cartridge needs to be replaced more often. Use the drain valves to slowly drain all reservoirs to zero psi. Allow the oil/water mixture to fully settle before measuring oil quantity. 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 oil-vapor 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.) 5 For certain vehicles/applications, where turbo-charged inlet air is used, a smaller size compressor may be permissible. 3 4
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 Bendix Tu-Flo 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 troubleshooting 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.

Bendix Commercial Vehicle Systems LLC
AIR DRYER APPLICATION GUIDELINE
The following Application Guideline is a point system that is calculated based on Vehicle Conguration and Vocation Options. Fill in points accordingly on each line and refer to Page 2 for dryer selections. If a particular entry is not valid for an application, then enter ZERO on that line. Refer to Page 3 for example applications. VEHICLE CONFIGURATION 1. Vehicle is equipped with bulk ofoading or Central tire ination. 2. For every axle (tractor and trailer including lifts): Add 1.0 point 3. For each non-steerable lift axle (additional points): Add 1.0 point 4. For each steerable lift axle (additional points): Add 0.5 point 5. Tractor and/or trailer is equipped with air suspension. Add 0.5 point VOCATION OPTIONS (CHOOSE THE ONE THAT BEST FITS) 6. Vehicle is used as a City Transit Bus. 7. Vehicle is used for pickup & delivery.
0.5 { a) Non-Fuel Hauler: Addpointpoint b) Fuel Hauler: Add 1.0

POINTS See Note 1

See Note 2
8. Vehicle is used for residential refuse. Add 4.5 points 9. Vehicle is used for rural or commercial refuse. Add 1.0 point 10. Vehicle is used as a dump truck or concrete mixer. Add 1.0 point 11. Vehicle is used for logging or construction. Add 1.0 point 12. Vehicle is used for line haul.
a) Single trailer No Points: b) Pulling three (3) to ve (5) axles on any trailer/dolly combination: Subtract 1.5 points: c) Pulling six (6) or more axles on any tailer/dolly combination: Subtract 2.5 points:
Add lines 1-12 and use this on Page 2
Vehicles equipped with either bulk ofoading or central tire ination are required to use two air dryers with an EverFlow Assembly. No points need to be calculated. Refer to Page 2 for proper dryer selection. 2 Requires an Extended Purge version of the dryer (AD-9 EP, AD-IP EP, AD-IS EP). No points need to be calculated. Refer to Page 2 for proper dryer selection.
DOCUMENTO CONTROLADO DE FORMATO ELECTRONICO: Antes de utilizarlo se requiere vericar el nivel de revision a la suciencia. CONTROLLED ELECTRONIC MEDIA DOCUMENT:Verication of revision level or adequacy is required prior to use.
Bendix Commercial Vehicle Systems LLC Elyria, OH 44035

Application

Increasing Performance
Point Total AD-SP AD-IP AD-9 AD-IS AD-9 EP AD-IP EP AD-IS EP

Air Dryers

Tandem Installed EverFlow Dryers4 Assembly5
Highway Travel Coach / RV City Transit Bus Air/Hydraulic School Bus City / Rural Route Fire Truck
N/R N/R N/R N/R 2-6 6.5-9

Pick-up & Delivery

2-6 6.5-9
Fuel Hauler (non-Bulk Ofoading) Line Haul

9.5-13 2-6 6.5-9

Rural and Commercial Refuse / Yard and Terminal Jockey Residential Refuse (with and without Work Brake) Dump Truck / Concrete Mixer

2-4 6.5-9 2-6 6.5-9

Off-Highway / Construction / Loggers

2-6 6.5-9 9.5-13

Bulk Ofoading Central Tire Ination Reservoir Drainage Frequency
N/R N/R Check Monthly Monthly / 4000 Miles
AD-9/AD-IP/AD-IS Dryer Selections Standard Purge Extended Purge Tandem Installed Dryers EverFlow Assembly Points 6 6.8

Point Totals

9 9.or above
The application chart is for reference only. If your truck does not fall into these guidelines, contact Benx Engineering or Technical Services at 1-800-AIR-BRAKE. N/R No Points Required Application is not dependent on point totals. 3 When selecting an AD-SP, note this dryer is intended for servicing low-demand air systems. For example, Line Haul applications are limited to single tandem axle trailers. 4 Tandem dryers must be matched models (i.e. two AD-IS or two AD-9, etc.). Both dryers must be extended purge versions. 5 There is no required compressor charge time or purge time. Operation is controlled through the EverFlow module.
Example #1:Typical Line Haul Application Vehicle Conguration 1. Not Applicable 2. Total number of all axles = 3 points 3. Total number of non-steerable lift axles = 0 points 4. Total number of steerable lift axles = 0 points 5. Tractor is equipped with air suspension = 0.5 points Vocation Options 6, 7, 8, 9, 10, 11 Not Applicable = 0 points 12. Standard line-haul hauling single trailer = 0 points. Total [ 3 + 0.5 = 3.5 points ] Selection choices include: AD-SP, AD-9, AD-IP or AD-IS.

A typical single axle, line haul vehicle: Air suspension. Three (3) axles total.
Example #2: Line Haul Pulling Single Axle Double
Vehicle Conguration 1. Not Applicable 2. Total number of all axles = 5 points 3. Total number of non-steerable lift axles = 0 points 4. Total number of steerable lift axles = 0 points 5. Tractor equipped with air suspension = 0.5 points Vocation Options 6, 7, 8, 9, 10, 11 Not Applicable = 0 points 12.Vehicle is used for line haul (3-5 axles) = -1.5 points Total [ 5 + 0.5 - 1.5 = 4 points ] Selection choices include AD-9, AD-IP or AD-IS. NOTE: An AD-SP is not acceptable in this application.
A 4x2 line haul vehicle pulling: (2) single axle trailers (1) single axle dolly Tractor air suspension Five (5) axles total
Recommended Service Intervals for Bendix Air Dryers
Air Usage Standard Medium Typical Vehicle Vocation Line haul, city delivery Double trailer trains, light transit, light off-highway Multiple trailer trains, city transit, heavy duty off-road Axles 5 or less 8 or less Standard Reservoir Drain Interval Desiccant (whichever comes rst) Cartridge Hours Mileage Time Replacement 900 25,months Every 3 years 450 12,months Every 2 years IPC Desiccant Cartridge Replacement AD-IP AD-IS AD-9 Every year Every year Every year Every year Every year Every year

11 or less

1 month

Every year

Drain reservoirs and change the desiccant cartridge more frequently if more than just traces of moisture are found in any of the reservoirs. IPC refers to cartridges that are enhanced with Integrated PuraGuard Coalescing ltration
Bendix Commercial Vehicle Systems LLC 901 Cleveland Street Elyria, Ohio 44035 1-800-AIR-BRAKE www.bendix.com BWBendix Commercial Vehicle Systems LLC, a member of the Knorr-Bremse Group 08/08 All Rights Reserved