BENDIX SD-01-700 User Manual

BENDIX® BA-922® COMPRESSOR

SD-01-700

DESCRIPTION

The function of the air compressor is to provide and maintain air under pressure to operate devices in the air brake systems. The Bendix® BA-922® compressor is a two cylinder, reciprocating compressor with a rated displacement of 31.6 cubic feet per minute at 1250 RPM.

The compressor consists of a water-cooled cylinder head, cooling plate, valve plate assembly, and an integral air cooled crankcase and cylinder block. The cast aluminum cylinder head contains the required air and water ports as well as two unloader pistons. The cast aluminum cooling plate provides added cooling and is located between the cylinder head and valve plate assemblies. The valve plate assembly consists of laminated, brazed steel plates which incorporate various valve openings and channels for conducting air and engine coolant into and out of the cylinder head.

The discharge valves are part of the valve plate assembly . The cylinder head, with the cooling and valve plates, comprise a complete cylinder head assembly.

The cast iron crankcase and cylinder block assembly houses the pistons, connecting rods, crankshaft and related bearings.

Air

Safety

Valve

Crankcase and

Cylinder Block

Unloader (2)

Cylinder

Head

Valve Plate

Assembly

FIGURE 1 - BENDIX® BA-922® COMPRESSOR

Delivery

Port

Intake

While not all compressors and charging systems are equipped with an optional discharge line safety valve, this component is recommended. The discharge line safety valve is installed in the cylinder head – or close to the compressor discharge port – and protects against over pressurizing the compressor in the event of a discharge line freeze up or blockage.

OPERATION

The compressor is driven by the vehicle engine and functions continuously while the engine is in operation. Actual compression of air is controlled by the compressor unloading mechanism operating in conjunction with a governor.

Unloader

Port

Cooling

Plate

Piston

Crankshaft

FIGURE 2 - BENDIX® BA-922® COMPRESSOR (CUT-AWAY)

Piston Rod

Discharge

Reed

Valves

Caterpillar

Detroit

Diesel

Detroit

Diesel

John

Deere

FIGURE 3 - TYPICAL COMPRESSOR DRIVE FLANGES

AIR INTAKE (LOADED)

During the piston down stroke, a vacuum is created in the cylinder bore above the piston. The vacuum causes the inlet reed valve to ﬂ ex open. Atmospheric air ﬂ ows through the open inlet valve and ﬁ lls the cylinder bore above the piston.

AIR COMPRESSION (LOADED)

When the piston reaches approximately bottom dead center (BDC), the inlet reed valve closes. Air above the piston is trapped by the closed inlet reed valve and is compressed as the piston begins to move toward top dead center (TDC). When air in the cylinder bore reaches a pressure greater than that of the system pressure, the discharge reed valves open and air ﬂ ows into the discharge line and air brake system.

Air, during the compression stroke, ﬂ ows into the hollow center of the unloader piston through an opening in the end of the piston. Compressed air acts on the interior surfaces of the unloader piston and, along with the unloader piston spring, holds the unloader piston against its seat on the valve plate. See Figure 6.

cavity and into the other cylinder. A small amount of air moves out of the inlet port. On the piston down stroke (TDC to BDC), air ﬂ ows in the reverse direction; from the other cylinder through the unloader piston to the inlet cavity , past the unseated unloader piston and into the cylinder bore.

Governor

Unloader Port

Reservoir

Port

Compressor

FIGURE 4 - BENDIX®BA-922® COMPRESSOR UNLOADER SYSTEM

Air

Discharge

Port

Air Inlet

Port

Air Dryer

Supply Reservoir

Discharge

Valve

Closed

Unloader

Port

NON-COMPRESSION OF AIR (UNLOADED)

When air pressure in the supply reservoir reaches the cut-out setting of the governor, the governor delivers system air to the compressor unloader port. Air entering the unloader port acts on the unloader piston, causing it to move away from its seat on the valve plate assembly. When the unloader piston is unseated a passage is opened between the cylinder bore, the air inlet cavity in the cylinder head, and the other cylinder. Air compression ceases. See Figure 7.

As the piston moves from bottom dead center (BDC) to top dead center (TDC), air in the cylinder bore ﬂ ows past the unseated unloader piston, into the cylinder head inlet

Cooling

Plate

Valve Plate

Inlet Valve Open

Piston Moving Down

FIGURE 5 - OPERATION - LOADED (INTAKE)

Unloader

Piston

Down &

Seated

Air Inlet

Air

Discharge

Port

Valve

Plate

Inlet

Valve

Closed

FIGURE 6 - OPERATION - LOADED (COMPRESSION)

Port

Discharge

Valve Open

Piston Moving Up

Unloader

Port

Unloader

Piston

Down &

Seated

LUBRICATION

The vehicle's engine provides a continuous supply of oil to the compressor. Oil is routed from the engine to the compressor oil inlet. An oil passage in the crankshaft conducts pressurized oil to precision sleeve main bearings and to the connecting rod bearings. Spray lubrication of the cylinder bores, connecting rod wrist pin bushings, and ball-type main bearings is obtained as oil is forced out around the crankshaft journals by engine oil pressure. Oil then falls to the bottom of the compressor crankcase and is returned to the engine through drain holes in the compressor mounting ﬂ ange.

COOLING

Air ﬂ owing through the engine compartment – from the action of the engine fan and the movement of the vehicle – assists in cooling the compressor. Cooling ﬁ ns are part of the crankcase/cylinder block casting. Coolant ﬂ owing from the engine cooling system through connecting lines enters the head and passes through internal passages in the cylinder head and valve plate assembly and is returned to the engine. Proper cooling is important in minimizing discharge air temperatures. Figure 8 illustrates the coolant ﬂ ow connections. See the tabulated technical data in the back of this manual for speciﬁ c requirements.

PREVENTATIVE MAINTENANCE

Regularly scheduled maintenance is the single most important factor in maintaining the air brake charging system. Refer to Table A in the Troubleshooting section

for a guide to various considerations that must be given to maintenance of the compressor and other related charging system components.

Important Note: Review the warranty policy before performing any intrusive maintenance procedures. An extended warranty may be voided if intrusive maintenance is performed during this period.

EVERY 6 MONTHS, 1800 OPERATING HOURS, OR AFTER EACH 50,000 MILES – WHICHEVER OCCURS FIRST – PERFORM THE FOLLOWING INSPECTIONS AND TESTS.

AIR INDUCTION

Bendix® BA-922® compressors are only permitted to be naturally aspirated: use of the engine turbocharger as an air source is not allowed.

Unloader Piston

Up & Unseated

Air From

Governor

Unloader

Port

Valve

Plate

Air in Pistons Mostly Shuttles Back

and Forth from One Piston to the

Other During Unloaded Mode

FIGURE 7 - OPERATION - UNLOADED

Air Inlet Port

Unloader

Piston

Up &

Unseated

A supply of clean air is one of the single most important factors in compressor preventative maintenance. Since the Bendix® BA-922® compressor receives supply air from the engine air ﬁ lter, periodic maintenance of the engine air ﬁ lter is necessary.

Inspect the compressor intake adapter, and the connecting hoses each time engine air cleaner maintenance is performed.

1. Inspect the intake hose adapters for physical damage. Make certain to check the adapters at both ends of the intake hose or tubing.

2. Inspect the intake hose clamps and tighten them if needed.

3. Inspect the intake hose or line for signs of drying, cracking, chafing and ruptures, and replace it as necessary.

COMPRESSOR COOLING

Inspect the compressor discharge port, inlet cavity, and discharge line for evidence of restrictions and carbon build-up. If more than 1/16" of carbon is found, thoroughly clean or replace the affected parts. Since carbon build-up generally indicates inadequate cooling, closely inspect the compressor cooling system. Check all compressor coolant lines for kinks and restrictions to ﬂ ow. Minimum coolant line size is 3/8" I.D. Check coolant lines for internal clogging from rust scale. If coolant lines appear suspicious, check the coolant ﬂ ow and compare to the tabulated technical data in the back of this manual. Carefully inspect the air induction system for restrictions.

LUBRICATION

Check the external oil supply line for kinks, bends, or restrictions to ﬂ ow. I.D.

Refer to the tabulated technical data in this manual

Supply lines must be a minimum of 3/16"

(page 10) for oil pressure minimum values. Check the exterior of the compressor for the presence of

oil seepage and refer to the TROUBLESHOOTING section (page 11) for appropriate tests and corrective action.

OIL PASSING

All reciprocating compressors pass a minimal amount of oil. Air dyers will remove the majority of oil before it can enter the air brake system. For particularly oil sensitive systems, the Bendix® PuraGuard® system ﬁ lter can be used in conjunction with a Bendix air dryer.

If compressor oil passing is suspected, refer to the TROUBLESHOOTING section and T ABLE A (page 13) for the symptoms and corrective action to be taken. In addition, Bendix has developed the “Bendix Air SystemInspection Cup” or BASIC kit to help substantiate suspected excessive oil passing. The steps to be followed when using the

Head

Bolt (6)

Inlet Port

Coolant In or Out

The cylinder head connection ports are identiﬁ ed with cast in numerals as follows:

(Compressors with no signal line to the unloader port should

FIGURE 8 - TYPICAL BA-922® COMPRESSOR CYLINDER

HEAD

Discharge

Safety Valve

CYLINDER HEAD PORT IDENTIFICATION

Atmospheric AIR IN 0 Compressed AIR OUT 21 Coolant IN or OUT 91 and 92 Governor Control 41

have a vent installed in the port rather than a plug.)

Unloader

Covers

Discharge

Port

Coolant In or

Out

Governor

Connection

BASIC kit are presented in APPENDIX A at the end of the TROUBLESHOOTING section.

COMPRESSOR DRIVE

Check for noisy compressor operation, which could indicate excessive drive component wear. Adjust and/or replace as necessary. Check all compressor mounting bolts and retighten evenly if necessary. Check for leakage and proper unloader mechanism operation. Repair or replace parts as necessary.

COMPRESSOR UNLOADER & GOVERNOR

Test and inspect the compressor and governor unloader system for proper operation and pressure setting.

1. Check for leakage at the unloader port. Replace leaking or worn o-ring.

2. Make certain the unloader system lines are connected as illustrated in Figure 3.

3. Cycle the compressor through the loaded and unloaded cycle several times. Make certain that the governor cuts in (compressor resumes compressing air) at a minimum of 105 psi (cut-out should be approximately 15-20 psi greater than cut-in pressure). Adjust or replace the governor as required.

4. Note that the compressor cycles to the loaded and unloaded conditions promptly. If prompt action is not noted, repair or replace the governor and/or repair the compressor unloader.

IMPORTANT NOTE

Replacement air governors must have a minimum cut-in pressure of 105 psi. The cut-in pressure is the

lowest system pressure registered in the gauges before the compressor resumes compressing air.

Compressors with no signal line to the unloader port should have a vent installed in the port rather than a plug.

SERVICE TESTS: GENERAL

The following compressor operating and leakage tests need not be performed on a regular basis. These tests should be performed when it is suspected that leakage is substantially affecting compressor buildup performance, or when it is suspected that the compressor is “cycling” between the load and unloaded modes due to unloader plunger leakage.

Note: When comparing build-up times, be sure to make an allowance for any air system modiﬁ cations which could cause longer times, such as adding air components or reservoirs. Always check for air system leakage.

LEAKAGE TESTS

See the standard Air Brake System and Accessory Leakage test on Page 24 (Test 2).

Note: Leakage in the air supply system (components before the supply reservoir - such as the governor, air dryer , reservoir drain cocks, safety valve and check valves) will not be registered on the vehicle dash gauges and must be tested separately. Refer to the various maintenance manuals for individual component leakage tests, and the Bendix “Test and Checklist” published in the Air Brake System Handbook (BW5057) and on the back of the Dual Circuit Brake System Troubleshooting card (BW1396).

IN-SERVICE OPERATING TESTS

Compressor Performance: Build-up Test

This test is performed with the vehicle parked and the engine operating at maximum recommended governed speed. Fully charge the air system to governor cut-out (air dryer purges). Pump the service brake pedal to lower the system air pressure below 80 psi using the dash gauges. As the air pressure builds back up, time from when the dash air pressure gauge passes 85 to the time it passes 100 psi. The time should not exceed 40 seconds. If the vehicle exceeds 40 seconds, test for (and ﬁ x) any air leaks and then re-test the compressor performance. If the vehicle does not pass the test the second time, use the Advanced Troubleshooting Guide for Air Brake Compressors – starting on page 1 1 of this document – to assist your investigation of the cause(s).

Note: All new vehicles are certiﬁ ed using the FMVSS 121 test (paragraph S5.1.1) by the vehicle manufacturer, however the above test is a useful guide for in-service vehicles.

Optional Comparative Performance Check

It may be useful to also conduct the above test with the engine running at high idle (instead of maximum governed speed), and record the time taken to raise the system pressure a selected range (for example, from 90 to 120 psi, or from 100 to 120 psi, etc.) and record it in the vehicle’s maintenance ﬁ les. Subsequent build-up times throughout the vehicle’s service life can then be compared to the ﬁ rst one recorded. (Note: the 40 second guide in the test above does not apply to this build-up time.) If the performance degrades signiﬁ cantly over time, you may use the Advanced Troubleshooting Guide for Air Brake Compressors, starting on page 11 of this document, to assist your investigation of the cause(s).

Cylinder Head

Check for cylinder head gasket air leakage.

1. With the engine running, lower air system pressure to 60 psi and apply a soap solution around the cylinder head. Check the gasket between the cylinder head and valve plate assembly and the reed valve/gasket between the valve plate assembly and cylinder block for air leakage.

2. No leakage is permitted. If leakage is detected, replace the compressor or repair the cylinder head using a genuine Bendix maintenance kit available from an authorized Bendix parts outlets.

Inlet, Discharge & Unloader

In order to test the inlet and discharge valves and the unloader piston, it is necessary to have shop air pressure and an assortment of ﬁ ttings. A soap solution is also required.

1. With the engine shut off, drain ALL air pressure from the vehicle.

2. Disconnect the inlet and discharge lines and remove the governor or its line or adapter ﬁ tting.

3. Apply 120-130 psi shop air pressure to the unloader port and soap the inlet port. Leakage at the inlet port should not exceed 50 sccm.

4. Apply 120-130 psi shop air pressure to the discharge port and then apply and release air pressure to the inlet port. Soap the inlet port and note that leakage at the inlet port does not exceed 20 sccm.

If excessive leakage is noted in tests 3 or 4, replace or repair the compressor using genuine Bendix® replacements or maintenance kits available from any authorized Bendix parts outlet.

While it is possible to test for inlet, discharge, and unloader piston leakage, it may not be practical to do so. Inlet and discharge valve leakage can generally be detected by longer compressor build-up and recovery times. Compare current compressor build-up times with the last several recorded times. Make certain to test for air system leakage, as described above, before making a determination that compressor performance has been lost.

Unloader leakage is exhibited by excessive compressor cycling between the loaded and unloaded condition.

1. With service and supply system leakage below the maximum allowable limits and the vehicle parked, bring system pressure to governor cut-out and allow the engine to idle.

2. The compressor should remain unloaded for a minimum of 5-10 minutes. If compressor cycling occurs more frequently, and service and supply system leakage is within tolerance (including any leakage that may be present at the air dryer exhaust), replace or repair the compressor unloader system using a genuine Bendix maintenance kit available from authorized Bendix parts outlets.

COMPRESSOR REMOVAL & DISASSEMBLY

GENERAL

The following disassembly and assembly procedure is presented for reference purposes and presupposes that a rebuild or repair of the compressor is being undertaken. Several maintenance kits are available. The instructions provided with these parts and kits should be followed in lieu of the instructions presented here.

MAINTENANCE KITS & SERVICE PARTS

Cylinder Head Gasket Kit ........................................5014472

Unloader Kit .............................................................5014473

Governor Adapter Kit ...............................................5008561

Compressor Seal Kit (crankcase) ............................5008559

CAT MD Seal Kit ......................................................5012367

CAT HD Seal Kit ......................................................5012369

Series 60 Seal Kit ....................................................5012371

ST-4 Discharge Safety Valve (7/8"-14 thrd.) ...............801116

ST-4 Discharge Safety Valve (M16-1.5 thrd.) ............800534

All components shown in Figure 10 with a key number are available in kits and/or as individual service parts.

GENERAL SAFETY GUIDELINES WARNING! PLEASE READ AND FOLLOW

THESE INSTRUCTIONS TO A VOID 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. Where speciﬁ cally directed, the parking brakes may have to be released, and/or spring brakes caged, and this will require that the vehicle be prevented from moving by other means for the duration of these tests/procedures.

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 vehicle’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 a Bendix

AD-IS be sure to drain the purge reservoir.

5. Following the vehicle manufacturer’s recommended procedures, deactivate the electrical system in a manner that safely removes all electrical power from the vehicle.

6. Never exceed manufacturer’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 components and kits. Replacement hardware, tubing, hose, ﬁ ttings, etc. must be of equivalent size, type and strength as original equipment and be designed speciﬁ cally 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 Automatic T raction Control (A TC), 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.

air dryer system or a dryer reservoir module,

brand replacement parts,

REMOVAL

In many instances it may not be necessary to remove the compressor from the vehicle when installing the various

Cylinder

Head

7 8

Cooling

Plate

Valve Plate

Assembly

Crankcase

Cylinder

Block

End Cover

Crankcase

Cover

Item Qty. Description Item Qty. Description Item Qty Description

1 2 Unloader Cover Cap Screw 61 1 O-Ring 11 22 Head Gasket 21 1 Unloader Cover 71 1 O-Ring 12 12 Inlet Reed Valve/Gasket 31 1 Unloader Cap Gasket 81 1 Unloader Piston 13 13 O-Ring 41 1 Unloader Balance Piston 91 1 O-Ring 14 13 Bottom Cover Gasket 51 1 Spring 10 1 ST-4™ Safety Valve

Notes: 1. Contained in Unloader Kit 5014473

2. Contained in Cylinder Head Gasket Kit 5014472

3. Contained in Seal Kits 5008559, 5008561, 5008557 & 5008558

FIGURE 9 - BENDIX®BA-922® COMPRESSOR EXPLODED VIEW OF SERVICEABLE PARTS

maintenance kits and service parts. The maintenance technician must assess the installation and determine the correct course of action.

These instructions are general and are intended to be a guide. In some cases additional preparations and precautions are necessary. In all cases follow the instructions contained in the vehicle maintenance manual in lieu of the instructions,

1. Block the wheels of the vehicle and drain the air pressure from all the reservoirs in the system.

2. Drain the engine cooling system and the cylinder head of the compressor. Identify and disconnect all air, water and oil lines leading to the compressor.

3. Remove as much road dirt and grease from the exterior of the compressor as possible.

precautions and procedures presented in this manual.

4. Remove the discharge and inlet ﬁ ttings, if applicable, and note their position on the compressor to aid in reassembly.

Note: If a cylinder head maintenance kit is being installed,

stop here and proceed to PREP ARA TION FOR DISASSEMBLY. If replacing the compressor continue.

5. Remove any supporting bracketing attached to the compressor and note their positions on the compressor to aid in reassembly.

6. Remove the ﬂ ange mounting bolts and remove the compressor from the vehicle.

7. Inspect gear and associated drive parts for visible wear or damage. Since these parts are precision ﬁ tted, they must be replaced if they are worn or damaged. If replacing the compressor or replacing the drive gear, remove the drive gear from the compressor crankshaft using a gear puller.

8. If the compressor is being replaced stop here and proceed to "Installing The Compressor" at the end of the assembly procedure.

PREPARATION FOR DISASSEMBLY

Remove the balance of road dirt and grease from the exterior of the compressor with a cleaning solvent. Mark the rear end cover or end cover adapter in relation to the crankcase. It is recommended, but not speciﬁ cally necessary, to mark the relationships of the cylinder head, cooling plate, valve plate assembly , crankcase and cylinder block assembly.

6. Remove the two bolts located in the center of the head. Gently tap the head, cooling plate and valve plate assembly with a soft mallet to break the gasket seal. Lift the cylinder head with cooling plate and valve plate assembly off the cylinder block.

7. Remove the metal reed valve/gasket (12).

8. Gently tap the head, cooling plate and valve plate assembly with a soft mallet to break the gasket seals. Then separate the cylinder head from the cooling plate and valve plate assembly and remove the gasket (11) between them.

9. Turn the aluminum cylinder head over to expose the interior portion of the head. Push the unloader piston (7) along with its o-rings (6, 8 & 9) out of the cylinder head.

CRANKCASE COVER

1. Remove the four crankcase cover cap screws securing the crankcase cover to the crankcase. Using a soft mallet, gently tap the crankcase cover to break the gasket seal. Remove the crankcase cover gasket (14).

REAR END COVER OR END COVER ADAPTER

1. Remove the four end cover cap screws that secure the rear end cover or end cover adapter to the crankcase.

2. Remove the rear end cover or end cover adapter from the crankcase. Remove the o-ring seal (13) from the end cover.

A convenient method to indicate the above relationships is to use a metal scribe to mark the parts with numbers or lines. Do not use marking methods such as chalk that can be wiped off or obliterated during rebuilding.

Prior to disassembly make certain that the appropriate kits and/or replacement parts are available. Refer to Figure 9 during the entire disassembly and assembly procedure.

CYLINDER HEAD

1. Remove the discharge safety valve (10) from the cylinder head.

2. To restrain the spring force exerted by balance piston spring (5), hold the unloader cover (2) in place while removing the two unloader cover cap screws (1). Carefully release the hold on the unloader cover until the spring force is relaxed, then remove the unloader cover (2).

3. Remove the unloader cover gasket (3).

4. Remove the balance piston (4) and its spring (5) from the cylinder head.

5. Remove the six hex head bolts and washers from the cylinder head.

CLEANING OF PARTS

GENERAL

All parts should be cleaned in a good commercial grade of solvent and dried prior to inspection.

CYLINDER HEAD

1. Carefully remove all gasket material adhering to the aluminum cylinder head, steel valve plate assembly and cast iron cylinder block. Make certain not to deeply scratch or mar the gasket surfaces. Pay particular attention to the gasket surfaces of the aluminum head.

2. Remove carbon deposits from the discharge and inlet cavities of the cylinder head and valve plate assembly . They must be open and clear in both assemblies. Make certain not to damage the aluminum head.

3. Remove rust and scale from the cooling cavities and passages in the head and valve plate assembly and use shop air to clear debris from the passages.

4. Check the threads in all cylinder head ports for galling. Minor chasing is permitted.

5. Make certain the unloader vent passage under the unloader cover (2) in the head is open and free of debris.

INSPECTION OF PARTS

CYLINDER HEAD & VALVE PLATE

1. Carefully inspect the cylinder head gasket surfaces for deep gouges and nicks. If detected, the compressor must be replaced.

2. Carefully inspect the valve plate assembly gasket surfaces for deep gouges and nicks. Pay particular attention to the metal gasket surface. A metal gasket (12) is used between the valve plate assembly and the cylinder block. This surface must be smooth and free of all but the most minor scratching. If excessive marring or gouging is detected, the compressor must be replaced.

3. Inspect the cylinder head for cracks or damage. With the cylinder head and head gasket secured to the valve plate assembly, apply shop air pressure to one of the coolant ports with all others plugged, and check for leakage by applying a soap solution to the exterior of the head. If leakage is detected in the cylinder head casting, replace the compressor.

END COVER OR END COVER ADAPTER

Check for cracks and external damage. Check the crankshaft main bearing surface in the end cover or end cover adapter, check for excessive wear and ﬂ at spots and replace the end cover if necessary. Check for galling of the oil port threads and replace the end cover or end cover adapter if necessary. Minor thread chasing is permitted but do not “recut” the threads if they are badly damaged.

CYLINDER BLOCK

1. Check the cylinder head gasket surface on the cylinder block for nicks, gouges, and marring. A metal gasket is used to seal the cylinder head to the cylinder block. This surface must be smooth and free of all but the most minor scratching. If excessive marring or gouging is detected, the compressor must be replaced.

DISCHARGE LINE

1. Inspect the discharge line for kinks, damage, or carbon deposits. Replace as necessary. See the advanced troubleshooting guide for more information.

ASSEMBLY

General Note: All torques speciﬁ ed in this manual are

assembly torques and typically can be expected to fall off after assembly is accomplished. Do not re-torque after initial assembly torques fall unless instructed otherwise. A compiled listing of torque speciﬁ cations is presented on page 11 of this manual.

INCH POUNDS TO FOOT POUNDS To convert inch pounds to foot pounds of torque, divide inch pounds by 12.

Example: 12

12 Inch Pounds

= 1 Foot Pound

FOOT POUNDS TO INCH POUNDS To convert foot pounds to inch pounds of torque, multiply foot pounds by 12. Example: 1 Foot Pound

x 12 = 12 Inch Pounds

CRANKCASE COVER

1. Position the crankcase cover gasket (14) on either the

crankcase or crankcase cover and install the crankcase cover on the crankcase using the four cap screws. "Snug" the four cap screws then torque to 62-71 inch pounds (7-8 Nm) using a crossing pattern.

CRANKCASE END COVER OR ADAPTER

1. Install the end cover o-ring (13) on the crankcase end

cover.

2. Orient the crankcase end cover or end cover adapter to

the crankcase using the reference marks made during disassembly. Carefully install the end cover or end cover adapter in the crankcase making certain not to damage the crankshaft bearing surface in it.

3. Install the four end cover screws or studs. "Snug" the

screws then tighten to 195 to 213 inch pounds (22-24 Nm) using a crossing pattern.

CYLINDER HEAD

1. Note the position of the protruding alignment pins on the

cylinder block. Install the metal inlet reed valve/gasket (12) over the alignment pins on the cylinder block.

2. Position the valve plate assembly on the cylinder block

so that the alignment pins in the cylinder block ﬁ t into the corresponding holes in the valve plate assembly.

3. Position and install one of the metal gaskets (11) over

the alignment bushings protruding from the valve plate assembly. When properly installed, the outline of the gasket matches the outline of the valve plate.

4. Install the cooling plate over the alignment bushings

protruding from the valve plate assembly . Again, when properly installed, the outline of the cooling plate matches the outline of the valve plate.

5. Position and install the other metal gasket (11) over the

alignment bushings protruding from the cooling plate assembly . The outline of the gasket matches the outline of the cooling plate.

6. Position and install the cylinder head over the alignment

bushings protruding from the cooling plate. Note: The alignment bushings will only ﬁ t into

two of the six cylinder head bolt holes.

7. Install the two center bolts and six hex head cylinder

head bolts and washers and snug them, then tighten evenly to a torque of 265 to 292 inch pounds (30-33 Nm) using the pattern shown in Figure 9.

8. Install the unloader piston (7) with its pre-installed

o-rings (6, 8, 9) in the cylinder head making certain not to damage them in the process.

9. Install the balance piston spring (5) in the unloader piston (7), then install the small diameter of the balance piston (4) through the center of the spring.

10. Install the unloader cover gasket (3) on the cylinder head making certain the unloader vent passage and both screw holes align.

11. Position the unloader cover (2) on top of the balance piston (4) making certain the stamped logo is visible.

12.Press and hold the unloader cover (2) in place on the cylinder head and install both unloader cover cap screws (1). Torque the cover cap screws (1) from 62 to 71 inch pounds (7-8 Nm).

INSTALLING THE COMPRESSOR

1. If the compressor was removed for replacement, install the drive components. T orque the crankshaft nut to

220 - 254 foot pounds (210-290 Nm).

2. Install any supporting bracketing on the compressor in the same position noted and marked during removal.

3. Install the gasket on the drive ﬂ ange of the compressor. Make certain oil supply or return holes in the gasket are properly aligned with the compressor and engine. Gasket sealants are not recommended. Secure the compressor on the engine and tighten the mounting bolts.

4. Install the discharge, inlet and governor adapter ﬁ ttings, if applicable, in the same position on the compressor noted and marked during disassembly. Make certain the threads are clean and the fittings are free of corrosion. Replace as necessary. See the Torque Speciﬁ cations for various ﬁ tting sizes and types of thread on page 11 of this manual.

5. Inspect all air, oil, and coolant lines and ﬁ ttings before reconnecting them to the compressor. Make certain o-ring seals are in good or new condition. Tighten all hose clamps.

6. Clean oil supply line. Before connecting this line to the compressor. Run the engine brieﬂ y to be sure oil is ﬂ owing freely through the supply line.

7. Before returning the vehicle to service, perform the Operation and Leakage Tests speciﬁ ed in this manual. Pay particular attention to all lines reconnected during installation and check for air, oil, and coolant leaks at compressor connections. Also check for noisy operation.

TESTING REBUILT COMPRESSOR

In order to properly test a compressor under operating conditions, a test rack for correct mounting, cooling, lubricating, and driving the compressor is necessary . Such tests are not compulsory if the unit has been carefully rebuilt by an experienced person. A compressor efﬁ ciency, or build-up test, can be run with realite ease. An engine

5, 11

1, 15

7,13

Sequence Torque (Nm)

1 . . . . . . . . . . . 13

2 . . . . . . . . . . . 13

3 . . . . . . . . . . . 20

4 . . . . . . . . . . . 20

5 . . . . . . . . . . . 20

6 . . . . . . . . . . . 20

7 . . . . . . . . . . . 20

8 . . . . . . . . . . . 20

FIGURE 10 - BENDIX® BA-922® COMPRESSOR HEAD BOLT TORQUE SEQUENCE

3, 9

8, 14

2, 16

4, 10

6, 12

Sequence Torque (Nm)

9 . . . . . . . . . . . 32

10 . . . . . . . . . . 32

11 . . . . . . . . . . 32

12 . . . . . . . . . . 32

13 . . . . . . . . . . 32

14 . . . . . . . . . . 32

15 . . . . . . . . . . 13

16 . . . . . . . . . . 13

lubricated compressor must be connected to an oil supply line of at least 15 psi pressure during the test and an oil return line must be installed to keep the crankcase drained. Connect to the compressor discharge port, a reservoir with a volume of 1500 cubic inches, including the volume of the connecting line. With the compressor operating at 2100 RPM, the time required to raise the reservoir(s) pressure from 85 psi to 100 psi should not exceed 5 seconds. During this test, the compressor should be checked for gasket leakage and noisy operation, as well as unloader operation and leakage. If the compressor functions as indicated, reinstall on the vehicle connecting all lines as marked in the disassembly procedure.

BENDIX® BA-922® COMPRESSOR SPECIFICA TIONS

Typical weight ................................................................. 60 lbs.

Number of cylinders ................................................................ 2

Bore Diameter ...................................... 3.622 in. (92.005 mm)

Stroke ................................................... 2.125 in. (53.970 mm)

Calculated displacement at 1250 RPM ..................... 31.7 CFM

Flow Capacity @ 1800 RPM & 120 PSI ......................25.2 CFM

Flow Capacity @ 3000 RPM & 120 PSI ......................38.4 CFM

Maximum recommended RPM ................................ 3000 RPM

Minimum coolant ﬂ ow maximum RPM ............... 2.0 Gals./Min.

Approximate horsepower required:

Loaded 1800 RPM at 120 PSIG ................................... 8.73 HP

Unloaded 1800 RPM .................................................... 1.96 HP

Maximum inlet air temperature ........................................ 170°F

Maximum discharge air temperature ............................... 350°F

Minimum oil pressure required ........................................ 15 PSI

Minimum oil-supply line size ...................................... 3/16" I.D.

Minimum unloader-line size ....................................... 3/16" I.D.

Minimum Governor Cut-out Pressure .............................120 PSI

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