Bendix Commercial Vehicle Systems TU-FLO 501 User Manual

Bendix® TU-FLO® 501 Air Compressor

SD-01-337

DESCRIPTION AND OPERATION

General

The function of the air compressor is to provide and maintain air under pressure to operate devices in the air brake and/ or auxiliary air systems.

Description

The Tu-Flo® 501 compressor is a two cylinder, single st age, reciprocating compressor with a rated displacement of 12 cubic feet of air per minute at 1250 R.P.M.

The Tu-Flo® 501 compressor is constructed from two major assemblies, the head and the crankcase. The head houses the discharge valving and is installed on the upper portion of the crankcase. The crankcase is a one piece casting combining the cylinder block and the crankcase. The upper portion of the casting houses the cylinder bores and inlet valving; and the lower portion, the crankshaft and main bearings. V arious mounting and drive configurations, required by the numerous vehicle engine designs, are obtained by bolting different mounting flanges, end covers, and base adapters to the crankcase. T wo horizontal governor mounting pads are located on either side of the upper portion of the crankcase to provide convenient governor mounting.

Two methods are employed for cooling the Tu-Flo® 501 compressor during operation. The cylinder head is connected to the engine’s cooling system, while the cylinder bore portion of the crankcase has external fins for efficient air cooling.

FIGURE 1 - VARIOUS COMPRESSOR MOUNTINGS

D-2 D-3D-1

All Tu-Flo® 501 compressors utilize the engine’s pressurized oil system to lubricate the internal moving parts.

A nameplate is attached to the crankcase to identify the compressor. The nameplate displays a Bendix piece number or in some cases an engine or vehicle manufacturer’s piece number, along with a serial number .

FIGURE 2 - COMPRESSOR NAMEPLA TE

OPERATION

General

The compressor is driven by the vehicle engine and is operating continuously while the engine is running. Actual compression of air is controlled by the compressor unloading mechanism and the governor. The governor is generally mounted on the compressor and maintains the brake system air pressure to a preset maximum and minimum pressure level.

Intake and Compression of Air (Loaded)

open inlet valve and into the cylinder (see Fig. 4). As the piston begins its upward stroke, the air that was drawn into the cylinder on the down stroke is being compressed. Air pressure on top of the inlet valve plus the force of its spring, returns the inlet valve to its seat. The piston continues the upward stroke and compressed air then flows by the open discharge valve, into the discharge line and on to the reservoirs (see Fig. 5). As the piston reaches the top of it s stroke and starts down, the discharge valve spring and air pressure in the discharge line returns the discharge valve to its seat. This prevents the compressed air in the discharge line from returning to the cylinder bore as the intake and compression cycle is repeated.

Non-Compression of Air (Unloaded)

When air pressure in the reservoir reaches the cut-out setting of the governor, the governor allows air to pass from the reservoir into the cavity beneath the unloader pistons. This lifts the unloader pistons and plungers. The plungers move up and hold the inlet valves off their seats (see Fig. 6).

With the inlet valves held off their seats by the unloader pistons and plungers, air is pumped back and forth between the two cylinders. When air is used from the reservoir and the pressure drops to the cut-in setting of the governor , the governor closes and exhausts the air from beneath the unloader pistons. The unloader saddle spring forces the saddle, pistons and plungers down and the inlet valves return to their seats. Compression is then resumed.

During the down stroke of the piston, a slight vacuum is created between the top of the piston and the head, causing the flat circular inlet valve to move up and off its seat. (Note the flat square discharge valve remains on its seat.) Atmospheric air is drawn through the air strainer by the

Discharge Line

Optional “Ping” T ank

Air Dryer

The Air Brake Charging System supplies the

compressed air for the braking system as well as other air accessories for the vehicle. The system usually consists of an air compressor, governor, discharge line, air dryer, and service reservoir.

Compressor

Governor

(Governor plus Synchro valve

for the Bendix

FIGURE 3A - SYSTEM DRAWING

DuraFlo™ 596

Compressor)

COMPRESSOR & THE AIR BRAKE SYSTEM

GENERAL

The compressor is part of the total air brake system, more specifically, the charging portion of the air brake system. As a component in the overall system its condition, duty cycle, proper installation and operation will directly affect other components in the system.

Powered by the vehicle engine, the air compressor builds the air pressure for the air brake system. The air compressor is typically cooled by the engine coolant system, lubricated by the engine oil supply and has its inlet connected to the engine induction system.

As the atmospheric air is compressed, all the water vapor originally in the air is carried along into the air system, as well as a small amount of the lubricating oil as vapor. If an air dryer is not used to remove these contaminants prior to entering the air system, the majority , but not all, will condense in the reservoirs. The quantity of contaminants that reach the air system depends on several factors including installation, maintenance and contaminant handling devices in the system. These contaminants must either be eliminated prior to entering the air system or after they enter .

DUTY CYCLE

The duty cycle is the ratio of time the compressor spends building air to the 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

Optional Bendix® PuraGuard® QC

™

Oil Coalescing Filter

Service Reservoir

(Supply Reservoir)

Reservoir Drain

from fittings, connections, lines, chambers or valves, etc. Refer to T able A in the Troubleshooting section for a guide to various duty cycles and the consideration that must be given to maintenance of other components.

COMPRESSOR INST ALLA TION

While the original compressor installation is usually completed by the vehicle manufacturer, conditions of operation and maintenance may require additional consideration. The following presents base guidelines.

DISCHARGE LINE

The discharge line allows the air, water-vapor and oil-vapor mixture to cool between the compressor and air dryer or reservoir. The typical size of a vehicle's discharge line, (see column 2 of T able A in the Troubleshooting section) assumes a compressor with a normal (less than 25%) duty cycle, operating in a temperate climate. See Bendix and/or other air dryer manufacturer guidelines as needed.

The discharge line must maintain a constant slope down from the compressor to the air dryer inlet fitting or reservoir to avoid low points where ice may form and block the flow . If, instead, ice blockages occur at the air dryer or reservoir 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. Shorter discharge line lengths or insulation may be required in cold climates.

While not all compressors and charging systems are equipped with a discharge line safety valve this component is recommended. The discharge line safety valve is installed in the cylinder head (Tu-Flo® 550/750) or close to the compressor discharge port and protects against over pressurizing the compressor in the event of a discharge line freezeup.

HOLE

DISCHARGE LINE TEMPERA TURE

When the temperature of the compressed air that enters the air dryer is within the normal range, the air dryer can remove most of the charging system oil. If the temperature of the compressed air is above the normal range, oil as oilvapor is able to pass through the air dryer and into the air system. Larger diameter discharge lines and/or longer discharge line lengths can help reduce the temperature.

THREAD

FIGURE 3B - DISCHARGE LINE SAFETY VALVE

TO RESERVOIR

INLET VALVE

DISCHARGE

VALVE

PISTON

TO GOVERNOR

STROKE

FIGURE 4 - INTAKE

TO RESERVOIR

DISCHARGE

VALVE

PISTON

STROKE

FIGURE 5 - COMPRESSION

DISCHARGE

VALVE

PISTON

INLET VALVE

TO GOVERNOR

TO RESERVOIR

INLET VALVE

UNLOADER

PLUNGER

INTAKE

STRAINER

UNLOADER

PLUNGER

INTAKE

STRAINER

UNLOADER

PLUNGER

INTAKE

STRAINER

The air dryer contains a filter that collects oil droplets, and a desiccant bed that removes almost all of the remaining water vapor. The compressed air is then passed to the air brake service (supply) reservoir. The oil droplets and the water collected are automatically purged when the governor reaches its "cut-out" setting.

For vehicles with accessories that are sensitive to small amounts of oil, we recommend installation of a Bendix PuraGuard® QC™ oil coalescing filter, designed to minimize the amount of oil present.

Lubrication

Since all Tu-Flo® 501 compressors are connected to the engine’s pressurized oil system, a continuous flow of oil is provided to the compressor, which is eventually returned to the engine.

Oil is fed into the compressor in various ways, for example: through the rear end cover, the drive end of the crankshaft or through the front flange adapter. An oil passage in the crankshaft conducts pressurized oil to the precision sleeve main bearings and to the connecting rod bearings. Splash lubrication of the cylinder bores, connecting rod wrist pin bushings, and the ball type main bearings, on some models, is obtained as oil is forced out around the crankshaft journals by engine oil pressure.

Check the exterior of the compressor for the presence of oil seepage and refer to the TROUBLESHOOTING section for appropriate tests and corrective action.

Cooling

Air flowing through the engine compartment from the action of the engine’s fan and the movement of the vehicle assists in cooling the crankcase. Coolant flowing from the engine’s cooling system through connecting lines enters the head and passes through the head’s water jacket and back to the engine. Proper cooling is important in maintaining discharge air temperatures below the maximum 400°F recommended.

STROKE

FIGURE 6 - UNLOADING

TO GOVERNOR

POLYURETHANE SPONGE STRAINER EVERY 5000 MILES OR 150 OPERATING HOURS

Remove and wash all of the parts. The strainer element should be cleaned or replaced. If the element is cleaned, it should be washed in a commercial solvent or a detergent and water solution. The element should be saturated in clean engine oil, then squeezed dry before replacing it in the strainer. Be sure to replace the air strainer gasket if the entire air strainer is removed from the compressor intake.

DRY ELEMENT-PLEATED PAPER AIR STRAINER

FIGURE 7 - POLYURETHANE SPONGE STRAINER

FIGURE 8 - P APER AIR STRAINER DRY ELEMENT -PLEA TED

EVERY 20,000 MILES OR 800 OPERATING HOURS

Remove the spring clips from either side of mounting baffle and remove the cover. Replace the pleated p aper filter and remount the cleaned cover making sure the filter is in position. Be sure to replace the air strainer gasket if the entire air strainer is removed from the compressor intake.

(NOTE: Some compressors are fitted with compressor

intake adapters which allow the compressor intake to be connected to the engine air cleaner.)

In this case, the compressor receives a supply of clean air from the engine air cleaner. When the engine air filter is changed, the compressor intake adapter should be checked. If it is loose, remove the intake adapter , clean the strainer plate, if applicable, and replace the intake adapter gasket, and reinstall the adapter securely . Check line connections both at the compressor intake adapter and at the engine air cleaner. Inspect the connecting line for ruptures and replace it if necessary.

EVERY 6 MONTHS, 1800 OPERATING HOURS OR AFTER EACH 50,000 MILES

FIGURE 9 - COMPRESSOR INT AKE ADAPTER

PREVENTIVE MAINTENANCE

Regularly scheduled maintenance is the single most important factor in maintaining the air brake charging system. Refer to T able A in the Troubleshooting section for a guide to various considerations that must be given to the maintenance of the compressor and other related charging system components.

Every month, 300 operating hours or after each 10,000 miles, depending on the operating conditions, experience and the type of strainer used, service the air strainer.

Remove the discharge head fittings and inspect the compressor discharge port and discharge line for excessive carbon deposits. If excessive buildup is noted in either , the discharge line must be cleaned or replaced and the compressor checked more thoroughly, paying special attention to the air induction system, oil supply and return system, and proper cooling. If necessary , repair or replace the compressor. Check for proper belt and pulley alignment and belt tension. Adjust if necessary, paying special attention not to over tighten the belt tension. Check for noisy compressor operation, which could indicate a worn drive gear coupling or a loose pulley. Adjust and/or replace as necessary. Check all compressor mounting bolts and retighten evenly if necessary . Check for leakage and proper unloader mechanism operation. Replace if defective in any way.

EVERY 24 MONTHS, 7200 OPERATING HOURS OR AFTER EACH 200,000 MILES

Perform a thorough inspection as indicated below and depending upon the results of this inspection or experience, disassemble the compressor, clean and inspect all parts thoroughly, repair or replace all worn or damaged parts using only genuine Bendix replacements or replace the compressor with a genuine Bendix remanufactured unit.

IMPORTANT - Should it be necessary to drain the engine cooling system to prevent damage from freezing, the cylinder head of the compressor must also be drained.

GENERAL SERVICE CHECKS

Inspection

It is of the utmost importance that the compressor receives a clean supply of air. The air strainer must be properly installed and kept clean. If the compressor intake is connected to the engine air cleaner, supercharger, etc., these connections must be properly installed and maintained. Check the compressor mountings to be sure they are secure. Check the drive for proper alignment, belt tension, etc.

Inspect the oil supply and return lines. Be sure these lines are properly installed and that the compressor is getting the proper supply of oil, and just as important, that the oil is returning to the engine. Check the coolant lines to and from the compressor and see that the cooling fins on the crankcase are not clogged with dirt, grease, etc. Check the unloader mechanism for proper and prompt operation.

FIGURE 10 - TU-FLO® 501 AIR COMPRESSOR (THRU DRIVE) EXPLODED VIEW

to the nearest authorized Bendix Distributor for a factory remanufactured compressor. If this is not possible, the compressor can be repaired using genuine Bendix replacement parts, in which case, the following information should prove helpful.

REMOVING AND DISASSEMBLY

Removing

Operating T ests

Vehicles manufactured after the effective date of FMVSS 121, with the minimum required reservoir volume, must have a compressor capable of raising air system pressure from 85-100 P.S.I. in 25 seconds or less. This test is performed with the engine operating at maximum governed speed. The vehicle manufacturer must certify this performance on new vehicles with appropriate allowances for air systems with greater than the minimum required reservoir volume.

Air Leakage T est s

Leakage past the discharge valves can be detected by removing the discharge line, applying shop air back through the discharge port and listening for escaping air. Also, the discharge valves and the unloader pistons can be checked for leakage by building up the air system until the governor cuts out, then stopping the engine. With the engine stopped, listen for escaping air at the compressor intake. To pinpoint leakage if noted, apply a small quantity of oil around the unloader pistons. If there is no noticeable leakage at the unloader pistons, the discharge valves may be leaking. If the compressor does not function as described above, or leakage is excessive, it is recommended that it be returned

These instructions are general and are intended to be a guide, in some cases additional preparations and precautions are necessary. Chock the wheels of the vehicle and drain the air pressure from all the reservoirs in the system. Drain the engine cooling system and the cylinder head of the compressor. Disconnect all air, water and oil lines leading to and from the compressor. Remove the drive gear(s) or pulley from the compressor crankshaft using a gear puller. Inspect the pulley or gear and associated part s for visible wear or damage. Since these parts are precision fitted, they must be replaced if they are worn or damaged.

DISASSEMBLY

General

Remove road dirt and grease from the exterior of the compressor with a cleaning solvent. Before the compressor is disassembled, the following items should be marked to show their relationship when the compressor is assembled. Mark both the front and rear end cover in relation to the crankcase. Mark the drive end of the crankshaft in relation to the front end cover and the crankcase. Mark the cylinder head in relation to the crankcase. Mark the base plate or base adapter in relation to the crankcase.

A convenient method to indicate the above relationship is to use a metal scribe to mark the parts with numbers or lines. Do not use a marking method that can be wiped off or obliterated during rebuilding, such as chalk. Remove all compressor attachments such as governors, air strainers or inlet fittings, discharge fittings and pipe plugs.

Cylinder Head

Remove the six cylinder head cap screws and tap the head with a soft mallet to break the gasket seal. Remove the inlet valve springs from the head and inlet valves from their guides in the crankcase. Remove inlet valve guides from around the inlet valve seats on the crankcase taking care not to damage seats. Scrape off any gasket material from the cylinder head and crankcase. Unscrew the discharge valve seats from the head and remove the discharge valves and springs. Inspect the discharge valve seats for nicks, cracks, and excessive wear and replace if necessary .

The discharge valve stops should be inspected for wear and replaced if excessive peening has occurred. To determine if excessive peening has occurred, measure the discharge valve travel. Discharge valve travel must not exceed .057 inches. T o remove the discharge valve stop s, support the machined surface of the cylinder head on an arbor press bed and gently press the stops from the top of the head and out the bottom. Be sure to allow sufficient clearance for the stops between the press bed and the bottom of the cylinder head. The valve stop bores in the cylinder head must be inspected for excessive scoring. A new head body must be used if scoring is excessive. Discard the inlet valves and springs, the discharge valves and springs and the discharge valve seats if defective.

Crankcase Base Plate or Adapter

Remove the cap screws securing the base plate or base adapter. T ap with soft mallet to break the gasket seal. Scrape off any gasket material from crankcase and plate or adapter .

Connecting Rod Assemblies

(Note: Before removing the connecting rods, mark each

connecting rod and its cap. Each connecting rod is matched to its own cap for proper bearing fit, and these parts must not be interchanged.)

Straighten the prongs of the connecting rod bolt lock strap and remove the bolts and bearing caps. Push the piston with the connecting rods attached out the top of the cylinders of the crankcase. Replace the bearing caps on their respective connecting rods. Remove the piston rings from the pistons. If the pistons are to be removed from the connecting rods, remove the wrist pin lock wires or teflon plugs and press the wrist pins from the pistons and connecting rods.

If the pistons are removed from the rod, inspect the bronze wrist pin bushing. Press out and replace the bushing if it is excessively worn. (See inspection of Parts) Discard the piston rings and the connecting rod journal bearings. Discard the wrist pin bushings if they were removed.

Crankcase

Remove the key or keys from the crankshaft and any burrs from the crankshaft where the key or keys were removed.

(Note: Through Drive Compressors may have a crankshaft

key at both ends.)

Remove the four cap screws securing front or drive-end end cover or flange adapter. Remove the end cover , taking care not to damage the crankshaft oil seal or front main bearing, if any. Remove both of the small seal rings from the crankcase, and the o-ring from around the front end cover. Remove the four cap screws securing the rear end cover and remove the rear end cover taking care not to damage the rear main bearing, if any . Remove both of the small seal rings from the crankcase and the o-ring from around the end cover. If the compressor has ball type main bearings, press the crankshaft and ball bearings from the crankcase, then press the ball bearings from the crankshaft. Remove the unloader spring, spring saddle, and spring seat from the inlet cavity of the crankcase, using long nose pliers. Remove the unloader plungers and guides. Cover the inlet cavity with a shop rag and apply air pressure to the governor mounting pad unloader port to blow the unloader pistons out of their bores and into the inlet cavity .

CLEANING OF P ARTS

General

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

Cylinder Head

Remove all the carbon deposits from the discharge cavities and all the rust and scale from the cooling cavities of the cylinder head body . Scrape all the foreign matter from the body surfaces and use shop air pressure to blow the dirt particles from all the cavities.

Crankcase

Clean the carbon and dirt from the inlet and unloader passages. Use shop air pressure to blow the carbon and dirt deposits from the unloader passages.

Oil Passages

Thoroughly clean all oil passages through the crankshaft, crankcase, end covers, and base plate or base adapter. Inspect the passages with a wire to be sure. Blow the loosened foreign matter out with air pressure.

OIL P ASSING

All reciprocating compressors currently manufactured will pass a minimal amount of oil. Air dryers will remove the majority of oil prior to entrance into the air brake system.

For particularly oil sensitive systems the Bendix

PuraGuard QC™ oil coalescing filter can be used in conjunction with a Bendix air dryer.

If compressor oil passing is suspected, refer to the TROUBLESHOOTING section and TABLE A for the symptoms and corrective action to be taken. In addition, Bendix has developed the "Bendix Air System Inspection Cup" or BASIC test to help substantiate suspected excessive oil passing. The steps to be followed when using the BASIC test are presented in APPENDIX A at the end of the TROUBLESHOOTING section.

INSPECTION OF PARTS

Cylinder Head Body

Inspect the cylinder head for cracks or damage. 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 body. If leakage is detected, replace the head.

End Covers

Check for cracks and external damage. If the crankshaft main bearings are installed in the end cover, check for excessive wear and flat spots and replace them if necessary . If the compressor has an oil seal in the end cover, it should be removed by pressing it out of the end cover.

Crankcase

Check all crankcase surfaces for cracks and damage. On compressors where ball bearing main bearings are used the difference between the O.D. of the outer race and the I.D. of the crankcase hole should be .0000 in. to .0015 in. loose. This is to maintain the correct press fit. The crankcase must be replaced if the fit is too loose.

On compressors fitted with precision, sleeve main bearings, the difference between the O.D. of the crankshaft journal and the main bearing I.D. must not exceed .0065 in. If the clearance is greater than .0065 in., the end cover or main bearing must be replaced.

Check the unloader bore bushings to be sure they are not worn, rusted, or damaged. If these bushings are to be replaced, they can be removed by running a 1/8 in. pipe thread tap into the bushing, and inserting a 1/8 in. pipe threaded rod and pulling the bushing straight up and out. Do not use an easy-out for removing these bushings. If the inlet valve seats are worn or damaged, so they cannot be reclaimed by facing, they should be replaced. Cylinder bores should be checked with inside micrometers or calipers. (Fig. 1 1). Cylinder bores which are scored or out of round by more than .001 in. or tapered more than .002 in. should be rebored or honed oversize. Oversized pistons and piston rings are available in .010 in., .020 in. and .030 in. oversizes. Cylinder bores must be smooth, straight, and round. Clearance between the cast iron pistons and cylinder bores should be between .002 in. minimum and .004 in. maximum.

PISTON RING OIL RING

PISTON RING

.002” .004”

CORRECT GAP CLEARANCE

WITH RINGS IN CYLINDER

OIL RING

EXPANDER RING

FIGURE 12 - CORRECT GROOVE CLEARANCE

.001” .003”

Pistons

Check the pistons for scores, cracks, or enlarged ring grooves; replace the pistons if any of these conditions are found. Measure each piston with a micrometer in relation to the cylinder bore diameter to be sure the diametral clearance is between .002 in. minimum and .004 in. maximum.

.002” .010”

FIGURE 1 1 - MEASURING CYLINDER BORES

Check the fit of the wrist pins to the pistons and connecting rod bushings. The wrist pin should be a light press fit in the piston. If the wrist pin is a loose fit, the piston and pin assembly should be replaced. Check the fit of the wrist pin in the connecting rod bushing by rocking the piston. This clearance should not exceed .0007 in. Replace the wrist pin bushings if excessive clearance is found. Wrist pin bushings should be reamed to between .5314 in. and .5317 in. after being pressed into the connecting rods.

Check the fit of the piston rings in the piston ring grooves. Check the ring gap with the rings installed in the cylinder bores. Refer to Fig. 12 for correct gap and groove clearances.

Crankshaft

Check the crankshaft threads, keyways, tapered ends and all machined and ground surfaces for wear, scores, or damage. Standard crankshaft journals are 1.1250 in. to

1.1242 in. in diameter. If the crankshaft journals are excessively scored or worn or out of round and cannot be reground, the crankshaft must be replaced. Connecting rod bearing inserts are available in .010 in., .020 in. and .030 in. undersizes for compressors with reground crankshafts. Main bearing journals must be maintained so the ball bearings are a snug fit or so that no more than .0065 in. clearance exists between the precision sleeve main bearing and the main bearing journals on the crankshaft. In crankshafts fitted with oil seal rings, the oil seal ring groove or grooves must not be worn. The ring groove walls must have a good finish and they must be square. Check to be sure the oil passages are open through the crankshaft.

Connecting Rod Bearings

Used bearing inserts must be replaced. Connecting rod caps are not interchangeable. The locking slots of the connecting rod and cap should be positioned adjacent to each other. Clearance between the connecting journal and the connecting rod bearing must not be less than .0003 in. or more than .0021 in. after rebuilding.

FIGURE 13 - DISCHARGE VAL VE, V AL VE STOP AND SEAT

FIGURE 14 - INLET VALVE AND SEA T

Inlet Valves and Seats

Inlet valves and springs should be replaced, if the inlet valve seats show signs of slight nicks or scratches. They can be redressed with a fine piece of emery cloth or by lapping with a lapping stone, grinding compound and grinding tool. If the seats are damaged to the extent that they cannot be reclaimed, they must be replaced. The dimension from the top of the cylinder block to the inlet valve seat should not exceed .1 13 in. nor be less than .101 in.

REPAIRS

Discharge Valves, Valve Stops and Seats

If the discharge valve seats merely show signs of slight wear , they can be dressed by using a lapping stone, grinding compound and grinding tool. If the discharge valve stops are to be replaced, an application of a sealer is required, such as “Locktite Retaining Compound #75.” Be sure that the press fit between the discharge valve stop outside diameter and the valve stop bore in the cylinder head is a minimum of .0008 in. and a maximum of .0028 in. If this fit can not be maintained, a new cylinder head body must be used. Be sure to completely support the outside top of the cylinder head casting, while pressing in the replacement stops. Install the new discharge valve springs and valves. Screw in the discharge valve seats. Discharge valve travel should be between .041 in. to .057 in.

T o test for leakage by the discharge valves, apply 100 pounds of air pressure through the cylinder head discharge port and apply a soap solution to the discharge valves and seats. A slight leakage in the form of soap bubbles is permissible. If excessive leakage is found, leave the air pressure applied and with the use of a fibre or hardwood dowel and a hammer, tap the discharge valves off their seats several times. This will help the valves to seat and should reduce the leakage. With the air pressure still applied at the discharge port of the cylinder head, check for leakage around the discharge valve stops exposed on the top of the cylinder head casting. No leakage is permitted.

ASSEMBLY

General Note: All torques specified in this manual are assembly torques and can be expected to fall off after

assembly is accomplished. Do not retorque after initial assembly torques fall.

T o convert inch pounds of torque to foot pounds of torque, divide inch pounds by 12.

inch pounds ÷ 12 = foot pounds

T o convert foot pounds of torque to inch pounds of torque, multiply foot pounds by 12.

foot pounds x 12 = inch pounds

Installing the Crankshaft Cautionary Note:

All flange mounted compressors must be assembled without a gasket between the crankcase and flange adapter and some compressors do not require gaskets on the end cover . Install the new crankcase gaskets only where they were removed during disassembly. In service failure of the compressor will occur if gaskets are used in disregard of the preceding.

If the compressor uses a ball type main bearing, press the ball bearing onto the correct end of the crankshaft. Position the ball bearing and the crankshaft in the crankcase, making sure the drive end of the crankshaft is positioned in the crankcase as marked before disassembly . Carefully press the crankshaft and ball bearing into the crankcase using an arbor press.

In the case of compressors with a front ball bearing, place two small seal rings in the counter-sunk holes at the front of the crankcase, as well as an end cover gasket. Install the front end cover in the proper position as marked before disassembly , taking care not to damage the new oil seal.

In the case of compressors with a rear ball bearing, place two small seal rings in the counter-bore at the rear of the crankcase. In one case a gasket is used and in another a large o-ring is placed in the counterbore at the rear of the crankcase. These are in addition to the seal rings. Install the rear end cover in the proper position as marked before disassembly. Since June, 1978, the two small seal rings have been increased slightly in cross section and a retaining ring added, as shown in Figure 15.

SEAL RING

OLD

O-RING RETAINER

SEAL RING

Secure the flange adapter, front or rear end cover to the crankcase by tightening the four cap screws. See note below for torque.

Note: For cast iron flange adapters, torque the four 7/16

in. cap screws to 38-45 foot pounds. For die cast aluminum end covers, torque the four 7/16 in. cap screws to 25-30 foot pounds. All end covers using 5/16 in. cap screws or stud and nuts are torqued to 15-18 foot pounds. For through drive compressors with a cast iron end cover, torque the four 7/16 in. cap screws to 25-30 foot pounds.

Pistons and Connecting Rods

If new wrist pin bushings are to be used, they should be pressed into the connecting rods so that the oil hole in the bushing lines up with the one in the rod. The new bushings should then be reamed or honed to provide between .0001 in. (.00254 mm) and .0006 in. (.01524 mm) clearance on the wrist pin. Position the connecting rod in the piston and press in the wrist pin.

Pistons installed in compressors manufactured prior to November, 1976, will have the wrist pin secured in the piston by a lock wire extending through matching holes in wrist pin and piston boss, anchored in a hole in the side wall of the piston. If the original pistons are used the wrist pin must be pressed in so the hole in the wrist pin aligns with that of the piston and secure same by inserting the new lockwire through the hole in piston and wrist pin and lock the wire by snapping the short 90° section into the lockwire hole in the bottom of the piston.

Compressors built after November, 1976, will have the wrist pin secured by Teflon buttons in either end of the wrist pin, allowing the wrist pin to float. The Teflon buttons pc. no. 292392 may be used with either new or old wrist pins. The later design pistons have two rings above the wrist pin and one below. Install the piston rings in the correct location with the ring pipmarks up. Stagger the position of the ring gaps. Pre-lubricate the piston, piston rings, wrist pins and connecting rod.

NEW

FIGURE 15

In the case of compressors with a sleeve bearing either front or rear, place the two small seal rings in the counter-sunk holes in the crankcase. Caution: An end cover gasket must not be used. Place the o-ring seal in the groove around the flange adapter or the end cover, and af fix the thrust washer. Install the flange adapter or end cover in the proper position as marked before disassembly , taking care not to damage the sleeve bearing.

Unloader

A new unloader kit should used when rebuilding. (Figure

14). (Piece Number 279615). The unloader pistons in the kit are pre-lubricated with a special lubricant piece number 239379 and need no additional lubrication. Install the unloader pistons in their bores being careful not to cut the o-rings. Position the unloader plungers in their guides and slip them in and over the tops of the pistons. Install the unloader spring seat in the crankcase inlet cavity; a small hole is drilled in the crankcase for this purpose. Position the saddle between the unloader piston guides, so its forks are centered on the guides. Install the unloader spring, making sure it seats over the spring seats both in the crankcase and on the saddle.

Position and install the inlet valve guides, then drop the inlet valves in their guides. The inlet valves should be a loose sliding fit in the guides.

During this test, the compressor should be checked for gasket leakage and noisy operation, as well as unloader operation and leakage.

INSPECTION OF REBUILT UNIT

Check to be sure that covers, plugs, or masking tape are used to protect all ports if compressor is not to be installed immediately . Fit the end of all crankshaf ts with keys, nut s, and cotter pins as required and then protect the ends against damage by wrapping with masking tape or friction tape. The open bottom of a vertical engine lubricated compressors should be protected against the entrance of dirt during handling or storage, by installing a temporary cover over the base.

COMPRESSOR TROUBLESHOOTING

FIGURE 16 - UNLOADER MECHANISM

Cylinder Head

Install the inlet valve springs in the cylinder head by applying a turning motion to the spring after it is in the head. The turning motion should dig the spring wire into the spring seat in the bottom of the spring bore in the head. Should this procedure fail after repeated attempts, use a very small quantity of grease to hold them in place, just enough to keep the springs from failing out. Place the cylinder head gasket on the cylinder block. Carefully align the cylinder head assembly on the block and install the cap screws, tightening them evenly to a torque of 25-30 foot pounds.

Base Plate or Base Adapter

Position the base plate or base adapter gasket on the crankcase and install the base plate or base adapter as marked before disassembly. Tighten the six cap screws securing the cast iron base adapter evenly to a torque of 38-45 foot pounds, and 12-16 foot pounds for base plate or aluminum cover.

T esting 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 efficiency or build-up test can be run which is not too difficult. An engine lubricated compressor must be connected to an oil supply line of at least 15 P.S.I. 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 connecting line. With the compressor operating at 2100 R.P .M., the time required to raise the reservoir(s) pressure from 85 P.S.I. to 100 P.S.I. should not exceed 7 seconds.

IMPORTANT: The troubleshooting cont ained in this section considers the compressor as an integrated component of the overall air brake charging system and assumes that an air dryer is in use. The troubleshooting presented will cover not only the compressor itself, but also other charging system devices as they relate to the compressor.

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 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 an AD-IS™ air dryer system or a dryer reservoir module, 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

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.

T ABULA TED DA T A

Number of cylinders 2 Bore size 2.625 in. Stroke 1.50 in. Piston displacement at 1250 RPM 12 cu. ft. Piston displacement per revolution 16.5 cu. in. Maximum recommended RPM

(naturally aspirated) 3000 Minimum coolant flow at maximum RPM 2.5 gal./min. Horsepower required at 3000 RPM

against 100 PSI head pressure 4.9 H.P. Recommended minimum discharge 5/8 in. OD

line size Copper Tube Recommended minimum oil return

line size 5/8 in. OD Tubing Recommended minimum oil supply

line size 1/4 in. OD Tubing Recommended minimum unloader

line size 1/4 in. OD Tubing Recommended minimum inlet cavity line

size (when compressor is

connected to engine air cleaner) 5/8 in. ID

minimum

Recommended minimum coolant line

size 1/2 in. OD Tubing Recommended maximum inlet air

temperature 250°F Recommended maximum discharge

air temperature 400°F Minimum pressure required to unload 60 PSI

This troubleshooting guide obsoletes and supersedes all previous published

troubleshooting information relative to Bendix air compressors.

Advanced Troubleshooting Guide

for Air Brake Compressors

The guide consists of an introduction to air brake charging system components, a table showing recommended vehicle maintenance schedules, and a troubleshooting symptom and remedy section with tests to diagnose most charging system problems.

Symptom Page Number

Air

Air brake charging system:

Slow build (9.0) . . . . . . . . . . . . . . . . . 21 - 22

Doesn’t build air (10.0) . . . . . . . . . . . . . . . 23

Air dryer:

Doesn’t purge (14.0) . . . . . . . . . . . . . . . . . 24

Safety valve releases air (12.0). . . . . . . . . 24

Compressor:

Constantly cycles (15.0) . . . . . . . . . . . . . . 24

Leaks air (16.0) . . . . . . . . . . . . . . . . . . . . . 25

Safety valve releases air (11.0). . . . . . . . . 23

Noisy (18.0) . . . . . . . . . . . . . . . . . . . . . . . . 25

Reservoir:

Safety valve releases air (13.0). . . . . . . . . 24

INDEX

Symptom Page Number

Coolant

Compressor leaks coolant (17.0) . . . . . . . . . . 25

Engine

Oil consumption (6.0) . . . . . . . . . . . . . . . . . . . 21

Oil

Oil Test Card results (1.0) . . . . . . . . . . . . . . . . 16

Oil is present:

On the outside of the compressor (2.0). . . 17 At the air dryer purge/exhaust

or surrounding area (3.0) . . . . . . . . . . . 17

In the supply reservoir (4.0). . . . . . . . 18 - 20

At the valves (5.0) . . . . . . . . . . . . . . . . . . . 20

At air dryer cartridge (7.0) . . . . . . . . . . . . . 21

In the ping tank or compressor

discharge aftercooler (8.0) . . . . . . . . . . 21

Test Procedures

(1) Oil Leakage at Head Gasket . . .26

(2) System Leakage . . . . . . . . . . . .26

(3) Compressor Discharge and

Air Dryer Inlet Temperature . . . . 26

(4) Governor Malfunction . . . . . . . .27

(5) Governor Control Line . . . . . . . . 27

(6) Compressor Unloader . . . . . . . .27

BASIC Test Information . . . . . . 29-31

Maintenance & Usage Guidelines

Maintenance Schedule and Usage Guidelines (Table A) . . 15

*This guide is only for vehicles that use desiccant air dryers.

Introduction to the Air Brake Charging System

Powered by the vehicle engine, the air compressor builds the air pressure for the air brake system. The air compressor is typically cooled by the engine coolant system and lubricated by the engine oil supply.

The compressor's unloader mechanism and governor (along with a synchro valve for the Bendix® DuraFlo 596 air compressor) control the brake system air pressure between a preset maximum and minimum pressure level by monitoring the pressure in the service (or “supply”) reservoir. When the air pressure becomes greater than that of the preset “cut-out”, the governor controls the unloader mechanism of the compressor to stop the compressor from building air and also causes the air dryer to purge. As the service reservoir air pressure drops to the “cut-in” setting of the governor, the governor returns the compressor back to building air and the air dryer to air drying mode.

As the atmospheric air is compressed, all the water vapor originally in the air is carried along into the air system, as well as a small amount of the lubricating oil as vapor.

The duty cycle is the ratio of time the compressor spends building air to the 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. The discharge line allows the air, water-vapor and oil-vapor mixture to cool between the compressor and

air dryer. The typical size of a vehicle's discharge line, (see column 2 of Table A on page 15) assumes a compressor with a normal (less than 25%) duty cycle, operating in a temperate climate. See Bendix and/or other air dryer manufacturer guidelines as needed.

™

When the temperature of the compressed air that enters the air dryer is within the normal range, the air dryer can remove most of the charging system oil. If the temperature of the compressed air is above the normal range, oil as oil-vapor is able to pass through the air dryer and into the air system. Larger diameter discharge lines and/or longer discharge line lengths can help reduce the temperature.

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 (see pages 32-34). Shorter discharge line lengths or insulation may be required in cold climates.

For vehicles with accessories that are sensitive to small amounts of oil, we recommended installation of a Bendix® PuraGuard® system filter, designed to minimize the amount of oil present.

Discharge Line

Optional “Ping” Tank

Compressor

The Air Brake Charging System supplies the

compressed air for the braking system as well as other air accessories for the vehicle. The system usually

Air Dryer

Governor

(Governor plus Synchro valve

for the Bendix

DuraFlo™ 596

Compressor)

consists of an air compressor, governor, discharge line, air dryer, and service reservoir.

Optional Bendix® PuraGuard System Filter or PuraGuard

QC™ Oil Coalescing Filter

™

Service Reservoir

(Supply Reservoir)

Reservoir Drain

Table A: Maintenance Schedule and Usage Guidelines

Regularly scheduled maintenance is the single most import ant factor in maintaining the air brake charging system.

Vehicle Used for:

Low Air Use

Compressor with less than 15% duty cycle

e.g. Line haul single trailer

w/o air suspension, air over

hydraulic brakes.

Compressor with up to 25% duty cycle

e.g. Line haul single trailer

with air suspension,

school bus.

High Air Use

Compressor with up to 25% duty cycle

e.g. Double/triple trailer, open

highway coach/RV, (most)

pick-up & delivery , yard or

terminal jockey, of f-highway,

construction, loggers, concrete

mixer, dump truck, fire truck.

Compressor with up to 25% duty cycle

e.g. City transit bus, refuse,

bulk unloaders, low boys,

urban region coach, central

tire inflation.

Column 1

Typical Discharge mended mended Reservoir

No. of Spec'd Cartridge Drain at Regular

Axles Replacement

Compressors Line Air Dryer Reservoir Oil Content s

less

550 air compressor

less

Tu-Flo

air compressor

™

Bendix

BA-921

Bendix

less

750 air compressor

Tu-Flo

air compressor

Bendix

596

™

, or DuraFlo

™

less

BA-922

Column 2 Column 3 Column 4 Column 5

Recom- Recom- Acceptable

I.D.

1/2 in.

For oil carry-over

control

Length

6 ft.

suggested

upgrades:

5/8 in. 9 ft.

9 ft.1/2 in.

For oil carry-over

control

suggested

upgrades:

Every 3

Years

Schedule2Drain Interval

Recom-

mended

Every

Month -

Max of

every 90

days

5/8 in. 12 ft.

1/2 in.

12 ft.

Every 2

For oil carry-over

control

suggested

upgrades:

5/8 in. 15 ft.

Years

BASIC test acceptable

5/8 in.

Every

Month

12 ft.

per month.

Every

For oil carry-over

suggested

control

upgrades:

Year

3/4 in. 15 ft.

BASIC test acceptable

range:

3 oil units

per month.

See

appendix

For the BASIC

Test Kit:

Order

Bendix

P/N

5013711

range:

5 oil units

See

appendix

Bendix

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 T o 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: T o 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 Bendix compressors, unloader service is

recommended every 250,000 miles.

Tu-Flo® 550 and 750

Air Brake Charging System Troubleshooting

How to use this guide:

Find the symptom(s) that you see, then move to the right to find the possible causes (“What it may indicate”) and remedies (“What you should do”). Review the warranty policy before performing any intrusive compressor maintenance. Unloader or cylinder head gasket replacement and resealing of the bottom cover plate are usually permitted under warranty . Follow all standard safety procedures when performing any maintenance.

Look for:

Normal - Charging system is working within normal range.

Check - Charging system needs further investigation.

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.

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 an AD-IS reservoir module, be sure to drain the purge reservoir.

™

air dryer system or a dryer

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 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.

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 (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.

replacement parts, components

Symptom: What it may indicate: What you should do:

1.0 Oil Test Card Results

Not a valid test.

Bendix

BASIC Test

Discontinue using this test.

Do not use this card test to diagnose compressor "oil passing" issues. They are subjective and error prone. Use only the Bendix Air System Inspection Cup (BASIC) test and the methods described in this guide for advanced troubleshooting.

The Bendix® BASIC test should be the definitive method for judging excessive oil fouling/oil passing. (See Appendix A, on

page 29 for a flowchart and expanded explanation of the checklist used when conducting the BASIC test.)

Symptom: What it may indicate: What you should do:

2.0 Oil on the Outside of the Compressor

2.1 Oil leaking at compressor / engine connections:

2.2 Oil leaking from compressor:

Engine and/or other accessories leaking onto compressor.

(a)Leak at the front or rear (fuel

pump, etc.) mounting flange.

(b)Leak at air inlet fitting.

(c)Leak at air discharge fitting.

(d)Loose/broken oil line fittings.

(a)Excessive leak at head gasket. (b)Leak at bottom cover plate.

(c)Leak at internal rear flange gasket.

Find the source and repair. Return the vehicle to service.

ð Repair or replace as necessary. If the

mounting bolt torques are low, replace the gasket.

ð Replace the fitting gasket. Inspect inlet

hose and replace as necessary.

ð Replace gasket or fitting as necessary to

ensure good seal.

ð Inspect and repair as necessary.

ð Go to Test 1 on page 26. ð Reseal bottom cover plate using RTV

silicone sealant.

ð Replace compressor.

(a)

3.0 Oil at air dryer purge/exhaust or surrounding area

(d)Leak through crankcase. (e)(If unable to tell source of leak.)

Head gasket and rear

flange gasket

(c)

Air brake charging system functioning normally.

locations.

ð Replace compressor. ð Clean compressor and check periodically.

(c)

ð Air dryers remove water and oil from the

air brake charging system. Check that regular maintenance is being performed. Return the vehicle to service. An optional kit (Bendix piece number 5011327 for the Bendix® AD-IS™ or AD-IP air dryers, or 5003838 for the Bendix AD-9™ air dryer) is available to redirect the air dryer exhaust.

™

Symptom: What it may indicate: What you should do:

4.0 Oil in Supply or Service Reservoir (air dryer installed)

(If a maintained Bendix PuraGuard® system filter or Bendix QC™ oil coalescing filter is installed, call 1-800-AIR-BRAKE (1-800-247-2725) and speak to a Tech Team member.)

See Table A, on page 15, for maintenance schedule information.

PuraGuard

Maintenance

(a)If air brake charging system

maintenance has not been

performed.

That is, reservoir(s) have not been drained per the schedule in Table A on p age 15, Column 4 and/or the air dryer maintenance has not been performed as in Column 3.

(b)If the vehicle maintenance has

been performed as recommended in Table A on page 15, some oil in the reservoirs is normal.

(a)

Drain

all air tanks (reservoirs) into the Bendix® BASIC test cup. (Bendix kit P/N 5013711).

ð Drain all air tanks and check vehicle at next

service interval using the Bendix

BASIC test. See Table A on page 15, column 3 and 4, for recommended service schedule.

ð Drain all air tanks into Bendix® BASIC test

cup (Bendix Air System Inspection Cup). If less than one unit of reservoir contents is found, the vehicle can be returned to service. Note: If more than one oil unit

of water (or a cloudy emulsion mixture) is present, change the vehicle's air dryer, check for air system leakage (T est 2, on page 26), stop inspection and check again at the next service interval. See the BASIC test kit for full details.

If less than one "oil unit" of water (or water/ cloudy emulsion mixture) is present, use the BASIC cup chart on the label of the cup to determine if the amount of oil found is within the acceptable level. ðIf within the normal range, return the vehicle to service. For vehicles with accessories that are sensitive to small amounts of oil, consider a Bendix PuraGuard® QC™ oil coalescing filter. ð If outside the normal range go to Symptom 4.0(c). Also see the Table A on page 15, column 3 for recommended air dryer cartridge replacement schedule.

Duty cycle too high

(c)Air brake system leakage. (d)Compressor may be undersized for

the application.

The duty cycle is the ratio of time the compressor spends building air to total engine running time. Air compressors are designed to build air (to "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.

ð Go to

Test 2 on page 26.

ð See Table A, column 1, on page 15 for

recommended compressor sizes. ð If the compressor is "too small" for the vehicle's role (for example, where a vehicle's use has changed or service conditions exceed the original vehicle or engine OE spec's) then upgrade the compressor. Note: The cost s incurred (e.g. installing a larger capacity compressor, etc.) are not covered under original compressor warranty. ð If the compressor is correct for the vehicle, go to Symptom 4.0 (e).

Symptom: What it may indicate: What you should do:

4.0 Oil in Supply or Service Reservoir* (air dryer installed) (continued)

(e)

(g)

Testing the temperature at the discharge fitting.

(g)

Kinked discharge line shown.

Temperature

(e) Air compressor discharge and/or

air dryer inlet temperature too high.

(f) Insufficient coolant flow.

(f)

Inspecting the coolant hoses.

(g) Restricted discharge line.

ð Check temperature as outlined in Test 3

on page 26. If temperatures are normal go to 4.0(h).

ð Inspect coolant line. Replace as necessary

(I.D. is 1/2").

ð Inspect the coolant lines for kinks and

restrictions and fittings for restrictions. Replace as necessary.

ð Verify coolant lines go from engine block

to compressor and back to the water pump. Repair as necessary.

ð If discharge line is restricted or more than

1/16" carbon build up is found, replace the discharge line. See Table A, column 2, on page 15 for recommended size. Replace as necessary.

ð 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 (Appendix B). Shorter discharge line lengths or insulation may be required in cold climates.

(h)

Other

(h)Restricted air inlet (not enough air

to compressor).

ð 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.

ð Check the engine air filter and service if

Partly collapsed inlet line shown.

*If a maintained Bendix filter is installed, call 1-800-AIR-BRAKE (1-800-247-2725) and speak to a Tech Team member.

PuraGuard® system filter or Bendix® PuraGuard® QC™ oil coalescing

necessary (if possible, check the air filter usage indicator).

Symptom: What it may indicate: What you should do:

4.0 Oil in Supply or Service Reservoir* (air dryer installed)

Other (cont.)

(i) Poorly filtered inlet air (poor air

quality to compressor).

(continued)

(j) Governor malfunction or setting. (k) Compressor malfunction.

Crankcase Flooding Consider installing a compressor bottom drain kit

(where available) in cases of chronic oil passing where all other operating conditions have been investigated. Bendix compressors are designed to have a 'dry' sump and the presence of excess oil in the crankcase can lead to oil carryover.

Inspect the engine air cleaner.

ð Check for leaking, damaged or defective

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.

ð Go to Test 4 on page 27. ð If you found excessive oil present in the

service reservoir in step 4.0 (b) above and you did not find any issues in steps 4.0 (c) through 4.0 (j) above, the compressor may be passing oil. Replace compressor. If still under warranty, follow normal warranty process. Note: After replacing a compressor, residual oil may take a considerable period of time to be flushed from the air brake system.

*If a maintained Bendix filter is installed, call 1-800-AIR-BRAKE (1-800-247-2725) and speak to a Tech Team member.

5.0 Oil present at valves (e.g. at

PuraGuard® system filter or Bendix® PuraGuard® QC™ oil coalescing

Air brake system valves are required to tolerate a light coating of oil.

ð A small amount of oil does not affect SAE

J2024** compliant valves.

exhaust, or seen during servicing).

ð 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 Bendix BASIC test cup (see also column 5 of T able A on page 15). Return the vehicle to service.

For oil-sensitive systems, see page 14.

** SAE J2024 outlines tests all air brake system pneumatic

components need to be able to pass, including minimum levels of tolerance to contamination.

Genuine Bendix valves are all SAE J2024 compliant.

Symptom: What it may indicate: What you should do:

6.0 Excessive oil consumption in engine.

7.0 Oil present at air dryer cartridge during maintenance.

8.0 Oil in ping tank or compressor discharge aftercooler.

9.0 Air brake charging system seems slow to build pressure.

A problem with engine or other engine accessory.

The engine service manual has more information.

Air brake charging system is functioning normally.

Oil shown leaking from an air dryer cartridge.

Air brake charging system is functioning normally.

(a)Air brake charging system

functioning normally.

ð See engine service manual.

ð 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 by the BASIC T est (see also column 5 of Table A on page 15). Replace the air dryer cartridge as needed and return the vehicle to service.

ð Follow vehicle O.E. maintenance

recommendation for these components.

ð Using dash gauges, verify that the

compressor builds air system pressure from 85-100 psi in 40 seconds or less with engine at full governed rpm. Return the

vehicle to service. (b)Air brake system leakage. (c)Compressor may be undersized for

the application.

(d) Compressor unloader mechanism

malfunction.

(e)Damaged compressor head

gasket.

ð Go to Test 2 on page 26. ð See Table A, column 1, on page 15 for

some typical compressor applications. If

the compressor is "too small" for the

vehicle's role, for example, where a

vehicle's use has changed, then upgrade

the compressor. Note: The costs incurred

(e.g. installing a larger capacity

compressor, etc.) are not covered under

original compressor warranty.

ð Go to Test 6 on page 27.

ð An air leak at the head gasket may indicate

a downstream restriction such as a

freeze-up or carbon blockage and/or could

indicate a defective or missing safety

valve. Find blockage (go to 9.0(f) for

details.) and then replace the compressor.

Do not re-use the safety valve without

testing. See Symptom 12.0(a).

Symptom: What it may indicate: What you should do:

9.0 Air brake charging system seems slow to build pressure. (continued)

Dash gauges.

(f) Restricted discharge line.

(f)

Kinked discharge line shown.

ð If discharge line is restricted:

ð By more than 1/16" carbon build up, replace the discharge line (see Table A, column 2, on page 15 for recommended size) and go to Test 3 on page 26. ð By other restrictions (e.g. kinks). Replace the discharge line. See Table A, column 2, on page 15 for recommended size. Retest for air build. Return vehicle to service or, if problem persist s, go to 9.0(a).

ð The discharge line must maintain a

(g)

Partly collapsed inlet line shown.

(g)Restricted air inlet (not enough air

to compressor).

(h)Poorly filtered inlet air (poor air

quality to compressor).

(i) Compressor malfunction.

ð Check compressor air inlet line for

restrictions, brittleness, soft or sagging hose conditions etc. Repair as necessary . Refer to vehicle manufacturer’s guidelines for inlet line size.

ð Check the engine air filter and service if

necessary (if possible, check the air filter usage indicator).

ð Check for leaking, damaged or defective

ð Replace the compressor only after making

certain that none of the preceding conditions, 9.0 (a) through 9.0 (h), exist.

Symptom: What it may indicate: What you should do:

10.0 Air charging system doesn’t build air.

* Note: For the Bendix® DuraFlo™ 596 air compressor, not only the governor, but also the SV-1™ synchro valve used would need to be tested. See Bulletin TCH-001-048.

11.0 Compressor safety valve releases air (Compressor builds too much air).

(a) Governor malfunction*. (b) Restricted discharge line. (c) Air dryer heater malfunction:

exhaust port frozen open.

(d) Compressor malfunction.

(a) Restricted discharge line.

Damaged discharge line shown.

ð Go to Test 4 on page 27. ð See 9.0(f). ð Replace air dryer heater.

ð Replace the compressor only after making

certain the preceding conditions do not exist.

ð If discharge line is restricted:

ð 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 B ul l e t in s TCH08-21 and TCH-08-22 (Appendix B). Shorter discharge line lengths or insulation may be required in cold climates.

(b)Downstream air brake system

check valves or lines may be blocked or damaged.

(c)Air dryer lines incorrectly installed.

(d) Compressor safety valve

malfunction.

(e) Compressor unloader mechanism

malfunction.

(f) Governor malfunction.

ð Inspect air lines and verify check valves

are operating properly.

ð Ensure discharge line is installed into the

inlet of the air dryer and delivery is routed to the service reservoir.

ð Verify relief pressure is 250 psi. Replace

if defective.

ð Go to Test 6 on page 27.

ð Go to Test 4 on page 27.

Symptom: What it may indicate: What you should do:

12.0 Air dryer safety valve releases air.

Air dryer safety valve

Technician removes governor.

13.0 Reservoir safety valve releases air

(a) Restriction between air dryer and

reservoir.

(b)Air dryer safety valve malfunction.

(c)Air dryer maintenance not

performed.

(d)Air dryer malfunction.

(e) Improper governor control line

installation to the reservoir.

(f) Governor malfunction.

(a)Reservoir safety valve malfunction.

(b) Governor malfunction.

ð Inspect delivery lines to reservoir for

restrictions and repair as needed.

ð Verify relief pressure is at vehicle or

component manufacturer specifications. Replace if defective.

ð See Maintenance Schedule and Usage

Guidelines (Table A, column 3, on page

15).

ð Verify operation of air dryer. Follow vehicle

O.E. maintenance recommendations and component Service Data information.

ð Go to Test 5 on page 27.

ð Go to Test 4 on page 27.

ð Verify relief pressure is at vehicle or

component manufacturer's specifications (typically 150 psi). Replace if defective.

ð Go to Test 4 on page 27.

14.0 Air dryer doesn’t purge. (Never hear exhaust from air dryer.)

15.0 Compressor constantly cycles (compressor remains unloaded for a very short time.)

(c)Compressor unloader mechanism

malfunction.

(a)Air dryer malfunction.

(b) Governor malfunction. (c)Air brake system leakage. (d)Improper governor control line

installation to the reservoir.

(a)Air brake charging system

maintenance not performed.

(b) Compressor unloader mechanism

malfunction.

check valve malfunction.

ð Go to Test 6 on page 27.

ð Verify operation of air dryer. Follow vehicle

O.E. maintenance recommendations.

ð Go to Test 4 on page 27. ð Go to Test 2 on page 26. ð Go to Test 5 on page 27.

ð Available reservoir capacity may be

reduced by build up of water etc. Drain and perform routine maintenance per Table A, columns 3 & 4, on page 15.

ð Go to Test 6 on page 27.

ð Verify operation of air dryer. Follow vehicle

O.E. maintenance recommendations and component Service Data information.

(d)Air brake system leakage.

ð Go to Test 2 on page 26.

Symptom: What it may indicate: What you should do:

16.0 Compressor leaks air

Testing for leaks with soap solution.

17.0 Compressor leaks coolant

(a)Compressor leaks air at

connections or ports.

(b) Compressor unloader mechanism

malfunction.

(c)Damaged compressor head

gasket.

Head

gasket

location

(a)Improperly installed plugs or

coolant line fittings.

ð Check for leaking, damaged or defective

compressor fittings, gaskets, etc. Repair

or replace as necessary.

ð Go to Test 6 on page 27.

ð An air leak at the head gasket may indicate

a downstream restriction such as a freeze-

up or carbon blockage and/or could

indicate a defective or missing safety

valve. Find blockage (go to 9.0(f) for

details.) and then replace the compressor .

Do not re-use the safety valve without

testing. See Symptom 12.0(a).

ð Inspect for loose or over-torqued fittings.

Reseal and tighten loose fittings and plugs as necessary. If overtorqued fittings and plugs have cracked ports in the head, replace the compressor.

18.0 Noisy compressor (Multi-cylinder compressors only)

This guide attempts to cover most compressor system problems. Here are some rare sources of problems not covered in this guide:

• Turbocharger leakage. Lubricating oil from leaking turbocharger seals can enter the air compressor intake and give misleading symptoms.

(b)Damaged compressor head

gasket.

(c)Porous compressor head casting.

(a) Damaged compressor.

Other Miscellaneous Areas to Consider

• Where a compressor does not have a safety valve installed, if a partial or complete discharge line blockage has occurred, damage can occur to the connecting rod bearings. Damage of this kind may not be detected and could lead to compressor problems at a later date.

ð An air leak at the head gasket may indicate

a downstream restriction such as a freezeup or carbon blockage and/or could indicate a defective or missing safety valve. Find blockage (go to 9.0(f) for details.) and then replace the compressor . Do not re-use the safety valve without testing. See Symptom 12.0(a).

ð If casting porosity is detected, replace the

compressor.

ð Replace the compressor.

Test s

Test 1: Excessive Oil Leakage at the

Head Gasket

Exterior leaks at the head gasket are not a sign that oil is being passed into the air charging system. Oil weepage at the head gasket does not prevent the compressor from building air.

Observe the amount of weepage from the head gasket. If the oil is only around the cylinder head area, it is acceptable (return the vehicle to service), but, if the oil weepage extends down to the nameplate area of the compressor, the gasket can be replaced.

Test 2: Air Brake System and Accessory Leakage

LOOK

FOR

WEEPAGE

Inspect for air leaks when working on a vehicle and repair them promptly. Park the vehicle on level ground and chock wheels. Build system pressure to governor cut-out and allow the pressure to stabilize for one minute. Step 1: Observe the dash gauges for two additional minutes without the service brakes applied. Step 2: Apply the service brakes and allow the pressure to stabilize. Continue holding for two minutes (you may use a block of wood to hold the

Test 3: Air Compressor Discharge

Temperature and Air Dryer Inlet

Temperature*

Caution: The temperatures used in this test are not normal vehicle conditions. Above normal temperatures can cause oil (as vapor) to pass through the air dryer into the air brake system.

This test is run with the engine at normal operating temperature, with engine at max. rpm. If available, a dyno may be used.

1. Allow the compressor to build the air system pressure to governor cut-in.

2. Pump the brakes to bring the dash gauge pressure to 90 psi.

3. Allow the compressor to build pressure from 95 to 105 psi gauge pressure and maintain this pressure range by cycling the brakes for

five (5) minutes.

pedal in position.) Observe the dash gauges. If you see any noticeable decrease of the dash air gauge readings (i.e. more than 4 psi, plus two psi for each additional trailer) during either two minute test, rep air the leaks and repeat this test to confirm that they have been repaired. Air leaks can also be found in the charging system, parking brakes, and/or other components - inspect and repair as necessary.

(* Note that only vehicles that have passed Test 2

would be candidates for this test.)

4. Then, while maintaining max rpm and pressure range, measure and record the surface temperature of the fittings:

ð at the compressor discharge port. (T1). ð at the air dryer inlet fitting. (T2).

Use a touch probe thermocouple for measuring the temperature.

5. See table below.

6. Retest before returning the vehicle to service.

T1 T2

Compressor Air Dryer

Discharge Inlet

Fitting Fitting

under under Temperatures are within

360°F 200°F normal range for this test, check

other symptoms. Go to 4.0 (h).

under over This could indicate a discharge

360°F 200°F line problem (e.g. restriction).

Call 1-800-AIR-BRAKE (1-800-247-2725) and speak with our Tech Team.

Action

Discharge Line

over __ Compressor is running hot.

360°F Check coolant 4(f) and/or

discharge line 4(g).

Tests (continued)

Test 4: Governor Malfunction

1. Inspect control lines to and from the governor for restrictions (e.g. collapsed or kinked). Repair as necessary.

2. Using a calibrated external gauge in the supply

Test 5: Governor Control Line

reservoir, service reservoir, or reservoir port of the D-2™ governor, verify cut-in and cutout pressures are within vehicle OEM specification.

3. If the governor is malfunctioning, replace it.

1. Ensure that the governor control line from the reservoir is located at or near the top of the reservoir. (This line, if located near the bottom of the reservoir, can become blocked or restricted by the reservoir contents e.g. water or ice.)

Test 6: Compressor Unloader Leakage

Bendix® Compressors: Park vehicle, chock

wheels, and follow all standard safety procedures. Remove the governor and install a fitting to the unloader port. Add a section of air hose (min 1ft long for a 1/2" diameter line) and a gauge to the fitting followed by a shut-off valve and an air source (shop air or small air tank). Open the shut

2. Perform proper reservoir drain intervals and air dryer cartridge maintenance per Maintenance Schedule and Usage Guidelines (Table A on page 15).

3. Return the vehicle to service.

off and charge the unloader port by allowing air pressure to enter the hose and unload the compressor. Shut off the air supply and observe the gauge. A steady reading indicates no leakage at the unloader port, but a falling reading shows that the unloader mechanism is leaking and needs to be serviced.

NOTES

Appendix A: Information about the BASIC Test Kit (Bendix P/N 5013711)

Service writer records info - including the number of days since all air tanks were ills out symptom

drained - and f

checklist. Technician inspects items.

START BASIC TEST

Park vehicle on ground.LEVEL

Chock wheels, drain air from system.

days

Bendix® Air System Inspection Cup

(BASIC) T est Information

Drain contents of air

tanks into

YES, this is a high air use vehicle.

Find the point on the label

where the number of oil units

High

meets the number of days*

since the vehicle's air tanks

were last drained.

Is the

point above

the HIGH Air Use

lineonthe

cup?

High

YES

ALL

BASIC cup

Is there less than one unit of liquid?

there more

than one unit of:

• water, or

• cloudy emulsion mixture?

NO, only oil.

Is this a

transit vehicle, bulk

unloader, or has more

than 5 axles?

Low

High

Low

YES

NO, this is a low air

use vehicle.

Find the point on the label

where the number of oil units

meets the number of days*

since the vehicle's air tanks

were last drained.

Is the

point above

the LOW Air Use

lineonthe

cup?

YES

Vehicle OK.

Return vehicle to

service.

Cloudy emulsion mixture

Is this vehicle being re-tested (after water, etc. was found

last time?)

Low

YES

Go to the

Advanced

Troubleshooting

Guide to find reason(s) for

presence of water

END TEST

Change air dryer

Test for air

leakage

END TEST

cartridge**

Use Test 2: Air Leakage

Re-test with the

BASIC Test after

30 days***

Test for air

leakage

Compressor

Use Test 2: Air Leakage

Does

the vehicle have

excessive air

leakage?

Was

the number of

days since last

draining known?

Replace the Compressor. If under warranty, follow standard procedures.

If, after a compressor was already replaced, the vehicle fails the BASIC test again, do not replace the compressor**** - use the Advanced Troubleshooting Guide to investigate the cause(s).

END TEST

YES

Repair leaks and

return vehicle to

service

NO (did not know

when last

drained)

YES, number of days was known (30 - 90 days)

Re-test with the

BASIC Test after

30 days***

END TEST

Vehicle OK.

Return vehicle to

service.

END TEST

* If the number of days since the air tanks were drained is unknown - use the 30 day line.

** Note: Typical air dryer cartridge replacement schedule is every 3 yrs/ 300K miles for low air use vehicles and every year/100K miles for high air use vehicles.

*** To get an accurate reading for the amount of oil collected during a 30 day period, ask the customer not to drain the air tanks before returning. (Note that 30-90 days is the recommended air tank drain schedule for vehicles equipped with a Bendix air dryer that are properly maintained.) If, in cold weather conditions, the 30 day air tank drain schedule is longer than the customer's usual draining interval, the customer must determine, based on its experience with the vehicle, whether to participate now, or wait for warmer weather. See the cold weather tips in Bulletins TCH-008-21 and TCH-008-22 (included on pages 32-34 of this document).

****Note: After replacing a compressor, residual oil may take a considerable period of time to be flushed from the air brake system.

Appendix A continued: Information about the BASIC Test Kit (Bendix P/N 5013711)

Filling in the Checklist for the Bendix® Air System Inspection Cup (BASIC) Test

Note: Follow all standard safety precautions. For vehicles using a desiccant air dryer.

The Service Writer fills out these fields with information gained from the customer

Number of Days Since Air Tanks Were Last Drained: ________ Date: ___________Vehicle #: ____________ Engine SN __________________________ Vehicle Used for: _______________Typical Load:________ (lbs.) No. of Axles: ____ (tractor) ____ (trailer) No. of Lift Axles: ____ Technician’s Name: ____________________

Checklist for Technician

Customer’s Complaint Have you confirmed complaint? (Please check all that apply)

“Relay valve q leaks oil / q malfunctions” . . . . . . . q no q yes*

The Service Writer also checks off any complaints that the customer makes to help the Technician in investigating.

“Dash valve q leaks oil / q malfunctions” . . . . . . . q no q yes*

q “Air dryer leaks oil” . . . . . . . . . . . . . . . . . . . . . . . q no q yes*

q “Governor malfunction” . . . . . . . . . . . . . . . . . . . . q no q yes*

q “Oil in gladhands” . . . . . . . . . . . . . . . . . . . . . . . . q no q yes*

how much oil did you find? ________________________________

q “Oil on ground or vehicle exterior” . . . . . . . . . . . q no q yes*

amount described: ______________________________________ q “Short air dryer cartridge life”

replaces every: ______________ q miles, q kms, or q months

q “Oil in air tanks” amount described:_______________________

We will measure amount currently found when we get to step B of the test.

q “Excessive engine oil loss” amount described: ______________

Is the engine leaking oil? . . . . . . . . . . . . . . . . . . . . . q no q yes*

Is the compressor leaking oil? . . . . . . . . . . . . . . . . . q no q yes*

q Other complaint: ______________________________________ q No customer complaint.

The Technician checks boxes for any of the complaints that can be confirmed.

Note: A confirmed com-

plaint above does NOT mean

that the compressor must be

replaced.

The full BASIC test below will

investigate the facts.

BASIC test starts here:

STEP A - Select one:

q This is a low air use vehicle: Line haul (single trailer) with 5 or less axles, or q This is a high air use vehicle: Garbage truck, transit bus, bulk unloader, or

line haul with 6 or more axles.

Then go to Step B.

The Technician selects the air use category for the vehicle. This decided which of the two acceptance lines on the cup will be used for the test below.

STEP B - Measure the Charging System Contents

1. Park and chock vehicle on level ground. Drain the air system by pumping the service brakes.

2. Completely drain ALL the air tanks into a single BASIC cup.

3. If there is less than one unit of contents total, end the test now and

return the vehicle to service. Vehicle passes.

4. If more than one oil unit of water (or a cloudy emulsion mixture)

is found:

(a) Change the vehicle’s air dryer cartridge

- see Footnote 1, (b) Conduct the 4 minute leakage test (Step D), (c) STOP the inspection, and check the vehicle

again after 30 days - see Footnote 2.

STOP + CK.

Oil

Units

Note for returning vehicles that are being retested after a water/cloudy emulsion mixture was found last time and the air dryer cartridge replaced: If more than one

oil unit of water or a cloudy emulsion mixture is found again, stop the BASIC test and consult the air dryer's Service Data sheet troubleshooting section.

Otherwise, go to Step C.

Footnote 1: Note: Typical air dryer cartridge replacement schedule is every 3 yrs/ 300K miles for low air use vehicles and every year/100K miles for

high air use vehicles. Footnote 2: To get an accurate reading for the amount of oil collected during a 30 day period, ask the customer not to drain the air tanks before

returning. (Note that 30-90 days is the recommended air tank drain schedule for vehicles equipped with a Bendix air dryer that are properly maintained.) If, in cold weather conditions, the 30 day air tank drain schedule is longer than the customer's usual draining interval, the customer must determine, based on its experience with the vehicle, whether to participate now, or wait for warmer weather. See the cold weather tips in Bulletins TCH-008-21 and TCH-008-22 (included in Appendix B of the advanced troubleshooting guide).

For an accurate test, the contents of all the air tanks on the vehicle should be used.

Appendix A continued: Information about the BASIC Test Kit (Bendix P/N 5013711)

Filling in the Checklist for the Bendix® Air System Inspection Cup (BASIC) Test

Note: Follow all standard safety precautions. For vehicles using a desiccant air dryer.

STEP C - How to Use the BASIC Test

The T echnician uses the chart (label) on the BASIC test cup to help decide the action to take, based on the amount of oil found. Use the lower acceptance line for low air use vehicles, and upper line for high air use vehicles (from Step A).

1. Record days since air tanks were last drained.

_________ days _________ units

If number of days is: 30-60 days (high air

use) or

30-90 days (low air use)

(if the number of days is unknown, or outside the

Otherwise . . .

limits above)

2. Record amount

if oil level is at or below

acceptance line for number

if oil level is above

acceptance line for number

of days è

if oil level is at or below

30-day acceptance line è

if oil level is above 30-day

acceptance line è

Acceptance

BASIC Test Example

An oil level of 4 units in a sixty-day period is within the acceptance area (at or below the line) for both low and high air use vehicles. Return the vehicle to service.

The Technician looks for the point where the number of days since the air tanks were drained meets the oil level. If it is at or below the (low or high use) acceptance line, the vehicle has passed the test. If the point is above the line we go to the leakage test.

STEP D - Air Brake System Leakage Test

Park the vehicle on level ground and chock wheels. Build system pressure to governor cut-out and allow the pressure to stabilize for one minute.

1: Observe the dash gauges for two additional minutes without the service brakes applied. 2: Apply service brakes for two minutes (allow pressure to stabilize) and observe the dash

gauges. If you see any noticeable decrease of the dash air gauge readings repair leaks. Repeat this test to confirm that air leaks have been repaired and return vehicle to service. Please repeat BASIC test at next service interval. Note: Air leaks can also be found in the charging system, parking brakes, and/or other components - inspect and repair as necessary.

Sixty days since last air

tank draining

of oil found:

of daysè

Lines

3. Action to take

System OK. Return to service.

System OK. Return to service. Stop inspection.

Test again after 30 days. See Footnote 2.

Decision point

Go to Step D

Oil

Level

Air leakage is the number one cause of compressors having to pump excessive amounts of air, in turn run too hot and pass oil vapor along into the system. Here the Technician conducts a four-minute test to see if leakage is a problem with the vehicle being tested.

STOP TEST

STOP + CK.

If no air leakage was detected, and if you are conducting

this test after completing Step C, go to Step E.

STEP E - If no air leakage was detected in Step D

Replace the compressor. Note: If the compressor is within warranty period,

please follow standard warranty procedures. Attach the completed checklist to warranty claim.

The Technician only reaches Step E if the amount of oil found, for the amount of time since the air tanks were last drained exceeds the acceptance level, AND the vehicle passes the four-minute leakage test (no noticeable leakage was detected).

Appendix B

T echnical Bulletin

Bulletin No.: TCH-008-021 Effective Date: 11/1/92 Page: 1 of 2

Subject: Air Brake System - Cold Weather Operation Tips

As the cold weather approaches, operators and fleets alike begin to look to their vehicles with an eye toward “winterization”, and particularly what can be done to guard against air system freeze-up. Here are some basic “Tips” for operation in the cold weather.

Engine Idling Avoid idling the engine for long periods of time! In addition to the fact that most engine

manufacturers warn that long idle times are detrimental to engine life, winter idling is a big factor in compressor discharge line freeze-up. Discharge line freeze-ups account for a significant number of compressor failures each year. The discharge line recommendations under “Discharge Lines” are important for all vehicles but are especially so when some periods of extended engine idling can not be avoided.

Discharge Lines

The discharge line should slope downward form the compressor discharge port without forming water traps, kinks, or restrictions. Cross-overs from one side of the frame rail to the other, if required, should occur as close as possible to the compressor. Fitting extensions must be avoided. Recommended discharge line lengths and inside diameters are dependent on the vehicle application and are as follows.

Typical P&D, School Bus and Line Haul

The maximum discharge line length is 16 feet. Length I.D. Min. Other Requirements

6.0-9.5 ft. ½ in. None

9.5-12 ft. ½ in. Last 3 feet, including fitting at the end of the discharge line, must be insulated with ½ inch thick closed cell polyethylene pipe insulation.

12-16 ft. 5/8 in. Last 3 feet, including fitting at the end of the

discharge line, must be insulated with ½ inch thick closed cell polyethylene pipe insulation.

If the discharge line length must be less than 6 feet or greater than 16 feet, contact your local Bendix representative.

Appendix B: Continued

Bulletin No.: TCH-008-021 Effective Date: 11/1/92 Page: 2 of 2

High Duty Cycle Vehicles (City Transit Coaches, Refuse Haulers, Etc.)

The maximum discharge line length is 16 feet. Length I.D. min. Other Requirements

10-16 ft. ½ in. None If the discharge line length must be less than 10 feet or greater than 16 feet, contact your local Bendix representative.

System Leakage

Check the air brake system for excessive air leakage using the Bendix “Dual System Air Brake Test and Check List” (BW1279). Excessive system leakage causes the compressor to “pump” more air and also more moisture into the brake system.

Reservoir Draining (System Without Air Dryer)

Routine reservoir draining is the most basic step (although not completely effective) in reducing the possibility of freeze-up. All reservoirs in a brake system can accumulate water and other contamination and must be drained! The best practice is to drain all reservoirs daily . When draining reservoirs; turn the ENGINE OFF and drain ALL AIR from the reservoir, better still, open the drain cocks on all reservoirs and leave them open over night to assure all contamination is drained (reference Service Data Sheet SD-04-400 for Bendix Reservoirs). If automatic drain valves are installed, check their operation before the weather turns cold (reference Service Data Sheet SD-03-2501 for Bendix DV-2™ Automatic Drain Valves). It should be noted that, while the need for daily reservoir draining is eliminated through the use of an automatic drain valve, periodic manual draining is still required.

Alcohol Evaporator or Injector Systems

Check for proper operation of these systems by monitoring alcohol consumption for a few days (Reference Service Data Sheet SD-08-2301 for the Bendix Alcohol Evaporator). Too little means the system is not receiving adequate protection and too much simply wastes alcohol. As a general guide, these systems should consume approximately 1 to 2 ounces of alcohol per hour of compressor loaded time (compressing air). City pick-up and delivery vehicles will operate with the compressors loaded (compressing air) more while compressors on highway vehicles will be loaded less. These figures are approximate and assume that air system leakage is within the limits of the Bendix “Dual System Air Brake Test and Check List” (BW1279). Last but not least, begin using alcohol several weeks prior to freezing weather to ensure that the system is completely protected. Use only methanol alcohol, such as Bendix “Air Guard”, in evaporators or injectors.

Air Dryers

Make certain air brake system leakage is within the limits stated in BW1279. Check the operation and function of the air dryer using the appropriate Service Data Sheet for the air dryer.

AD-9™ Air Dryer Service Data Sheet SD-08-2412 AD-4™ Air Dryer Service Data Sheet SD-08-2407 AD-2™ Air Dryer Service Data Sheet SD-08-2403 AD-IP™ Air Dryer Service Data Sheet SD-08-2414 AD-SP™ Air Dryer Service Data Sheet SD-08-2415 Trailer System-Guard™ Air Dryer Service Data Sheet SD-08-2416

Appendix B: Continued

T echnical Bulletin

Bulletin No.: TCH-008-022 Effective Date: 1/1/1994 Page: 1 of 1

Subject: Additional Cold Weather Operation Tip s for the Air Brake System

Last year we published Bulletin PRO-08-21 which provided some guidelines for “winterizing” a vehicle air brake system. Here are some additional suggestions for making cold weather vehicle operation just a little more bearable.

Thawing Frozen Air Lines

The old saying; “Prevention is the best medicine” truly applies here! Each year this activity accounts for an untold amount of unnecessary labor and component replacement. Here are some Do’s and Don’ts for prevention and thawing.

Do’s

1. Do maintain freeze prevention devices to prevent road calls. Don’t let evaporators or injectors run out of methanol alcohol or protection will be degraded. Check the air dryer for proper operation and change the desiccant when needed.

2. Do thaw out frozen air lines and valves by placing the vehicle in a warmed building. This is the only method for thawing that will not cause damage to the air system or its components.

3. Do use dummy hose couplings on the tractor and trailer.

4. Do check for sections of air line that could form water traps. Look for “drooping” lines.

Don’ts

1. Do not apply an open flame to air lines and valves. Beyond causing damage to the internal nonmetallic parts of valves and melting or burning non-metallic air lines. WARNING: THIS

PRACTICE IS UNSAFE AND CAN RESULT IN VEHICLE FIRE!

2. Do not introduce (pour) fluids into air brake lines or hose couplings (“glad hands”). Some fluids used can cause immediate and severe damage to rubber components. Even methanol alcohol, which is used in Alcohol Evaporators and Injectors, should not be poured into air lines. Fluids poured into the system wash lubricants out of valves, collect in brake chambers and valves and can cause malfunction. Loss of lubricant can affect valve operating characteristics, accelerate wear and cause premature replacement.

3. Do not park a vehicle outside after thawing its air system indoors. Condensation will form in the system and freeze again. Place the vehicle in operation when it is removed to the outdoors.

Supporting Air and Electrical Lines

Make certain tie wraps are replaced and support brackets are re-assembled if removed during routine maintenance. These items prevent the weight of ice and snow accumulations from breaking or disconnecting air lines and wires.

Automatic Drain Valves (System without Air Dryer)

As we stated last year, routine reservoir draining is the most basic step (although not completely effective) in reducing the possibility of freeze-up. While automatic drain valves relieve the operator of draining reservoirs on a daily basis, these valves MUST be routinely checked for proper operation. Don’t overlook them until they fail and a road call is required.

Bendix Commercial Vehicle Systems TU-FLO 501 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual