AIR COMPRESSORS TU-FLO 300, 400, 500, 501, 600, 700 & 1000 C Caterpillar

Tu-Flo 300 Compressor

Usage:

Important! Please Read

When working on or around air brake systems and components, the following precautions should be observed:

1. Always block vehicle wheels. Stop engine when working under a vehicle. Depleting vehicle air system pressure may cause vehicle to roll. Keep hands away from chamber push rods and slack adjusters; they may apply as system pressure drops.

2. Never connect or disconnect a hose or line containing air pressure. It may whip as air escapes. Never remove a component or pipe plug unless you are certain all system pressure has been depleted.

3. Never exceed recommended air pressure and always wear safety glasses when working with air pressure. Never look into air jets or direct them at anyone.

4. Never attempt to disassemble a component until you have read and understand recommended procedures. Some components contain powerful springs and injury can result if not properly disassembled. Use only proper tools and observe all precautions pertaining to use of those tools.

Description And Operation

Fig. 1-Piping Diagram Showing a Compressor in an Air Brake System

General

The Tu-Flo 300 Compressor is primarily used in air over hydraulic brake systems (Figure 1). Another use for this type compressor is in air supply systems for service trucks used for inflating tires, cleaning, driving tools, etc.

Description

Figures 2 and 3

Fig. 4-Compressor Oiling Systems

Tu-Flo 300 Compressors are single stage, reciprocating piston types. Their rated capacity in piston displacement when running at 1250 RPM is 4 cubic feet per minute. They are designed for vertical mounting and are fitted for belt drive only. Only air cooled type Tu-Flo 300 Compressors are made.

Tu-Flo 300 Compressors have automatic type inlet valves. Their unloading mechanisms are located in the cylinder block and they have no external moving parts.

Tu-Flo 300 Compressors are either engine (Figure 2) or self-lubricated (Figure 3). If engine lubricated, they receive their oil supply for lubrication from the engines on which they are mounted. Self-lubricated compressors contain their own oil supply and pumping system. The method of lubricating the moving parts is the same in either type (Figure 4). Oil is forced through an oil passage in the crankshaft and out at each connecting rod journal. As the crankshaft turns, the oil that is forced out at the journals is splashed against the cylinder bores and crankshaft bearings.

Die cast aluminum connecting rods and cast iron pistons are used in the Tu-Flo 300 Compressor. The wrist pins are lubricated by oil dripping from a drip-boss on the piston into a catch-funnel at the top of the connecting rod and through a drilled passage to the wrist pin and its bushing.

A name plate is attached to the crankcase of all Tu-Flo 300 Compressors. It shows the piece number, compressor type, and a serial number. The nameplate with a black background indicates a new compressor; if the background is red it indicates that the compressor is a factory reconditioned unit. The piece number identifies the compressor and it is the number used when reference is made to a particular unit. The serial number and type are additional information.

Operation

The air compressor runs whenever the engine runs, but it only compresses air when the governor is cut in. The governor starts or stops the compression by acting in conjunction with the compressor unloader mechanism located in the cylinder block. When the desired maximum and minimum system pressures are reached the governor either unloads or loads the compressor.

Intake And Compression (Loaded) Figures 5 and 6

Fig. 5-Intake of Air

Fig. 6-Compression of Air

During the down stroke of the piston a slight vacuum is created above the piston. Air from the outside then moves the inlet valve off its seat and is drawn into the cylinder bore above the piston. As the piston starts its upward stroke, the air that was drawn in on the down stroke starts to compress and returns the inlet valve to its seat. The air above the piston is further compressed until it overcomes the discharge valve spring and system air pressure to move the discharge valve off its seat. With the discharge valve open, the compressed air is forced through the discharge line to the reservoir.

As the piston reaches the top of its stroke and starts down, the discharge valve spring returns the discharge valve to its seat. This prevents the compressed air from returning to the cylinder bore as the intake and compression cycle is repeated.

Non-Compression (Unloaded) Figure 7

Fig. 7-Compressor Unloading Mechanism

When reservoir air pressure reaches the high pressure setting of the governor, it passes through the governor and into the cavity beneath the unloader pistons in the compressor cylinder block. The unloader pistons lift and the plungers move up and hold the inlet valves off their seats.

With the inlet valves held off their seats by the unloader pistons and plungers, air is merely forced back and forth between the two cylinders. As reservoir air is used and the pressure drops to the low pressure setting of the governor, the governor closes and exhausts the air from beneath the unloader pistons. The unloader spring forces the saddle, pistons and plungers down and the inlet valves again seat. Compression is then resumed.

Preventive Maintenance

Fig. 8-Oil Level

If the compressor is a self-lubricated type, its oil level should be checked at the same time the engine oil level is checked. The oil level should be kept from overflow out of the crankcase to the bottom of the dipstick (Figure 8). The oil should be changed at same time as engine oil or often enough to keep it non-abrasive and non-corrosive.

Every 100 Operating Hours Or After Each 5,000 Miles

Fig. 9-Exploded View of Compressor Air Strainer

Depending on operating conditions and experience, the compressor air strainer should be serviced (Figure 9). Remove and wash all parts and clean or replace element. If the element is cleaned it should be washed in gasoline, methyl alcohol, carbon tetrachloride, or soap and water. Before replacing the element it should be saturated in clean oil, then squeezed dry.

Check compressor drive alignment and belt tension. Also note that all mounting bolts are tightened securely.

Every 350 Operating Hours Or After 10,000 Miles

If compressor is self-lubricated type the oil should be drained, the crankcase flushed then filled with clean oil. The same SAE grade oil as is generally used in engines should be used in the compressor.

Every 1000 Operating Hours Or After Each 35,000 Miles

Remove cylinder head cover and check for presence of excessive carbon deposits. Also check discharge line for restriction due to carbon deposits. If restrictions are found in either of these checks, the cylinder head or discharge line should be cleaned or replaced.

The crankcase breather of self-lubricated type compressor should be serviced. It can be flushed with a good cleaning solvent and dried.

Every 3000 Operating Hours Or After Each 100,000 Miles

Depending upon operating conditions and experience, the compressor should be disassembled, cleaned and all parts inspected. All damaged or worn parts should be replaced or the complete compressor should be replaced with a factory reconditioned repair exchange unit.

Service Checks

It is of the utmost importance that the compressor is taking in clean air. The air strainer must be properly installed and kept clean.

Check compressor mounting to be sure it is secure. The drive should be checked for alignment, and proper belt tension.

If the compressor is engine lubricated its oil supply and return lines must be inspected to see that the compressor is getting the proper supply of oil and that the oil is returning to engine unrestricted.

Check to make sure the engine fan blast is flowing by the compressor unrestricted.

Compressor unloading mechanism should be checked for proper operation.

Operating Tests

Because of the many different types of air systems using the Tu-Flo 300 Compressor on different types of vehicles, it is difficult to set up a specific series of tests to determine the serviceability of the compressor on the vehicle. The best guide is familiarization with the vehicle and its air system. Should the compressor fail to maintain adequate air pressure in the system, it usually denotes loss of efficiency due to wear, provided leakage in the air system is not excessive. Oil passing is another sign of wear.

Air Leakage Tests

The discharge valves and the unloader pistons can be checked for leakage by first building up the air system until the governor cuts out, then stopping the engine. With the engine stopped, carefully listen for escaping air at the intake to pin-point leakage, if noted, squirt a little oil around the unloader pistons. If there is no noticeable leakage at the pistons, the discharge valves may be leaking.

Another method of checking the discharge valves is to disconnect the discharge line and apply shop air back through the discharge port.

If the compressor does not function as described above, or leakage is excessive, it is recommended that it be returned to the nearest Bendix-Westinghouse authorized distributor for a factory rebuilt compressor under the repair exchange plan. If this is not possible, the compressor can be repaired with genuine Bendix-Westinghouse parts in which case the following information should prove helpful.

Removing And Installing

These instructions are general and in some cases additional precautions must be taken.

Block vehicle to hold by means other than air brakes.

Drain air brake system.

Disconnect all air and oil lines to and from compressor.

Remove compressor mounting bolts, and compressor from engine.

Use a gear puller to remove the pulley from the compressor crankshaft.

Installation Engine Lubricated Types

Clean oil supply line. Before connecting the supply line run the engine briefly to make sure oil is flowing freely through the line.

Clean the oil return line or oil return passages in the bracket; these passages must unrestricted.

Prelubricate compressor cylinder walls and bearings with clean engine oil.

Always use a new mounting gasket.

Self-Lubricated Type

Fill compressor crankcase with clean engine oil before installing and operating compressor. Refer to "Tabulated Data" Section for proper amount of oil to be used.

All Types

Inspect pulley and associated parts for wear or damage. The pulley must be a tapered interference fit on the compressor crankshaft. Replace pulley if worn or damaged.

Install the pulley on the crankshaft making sure it does not ride on the key. Install crankshaft nut securely and lock with cotter pin.

Be sure the air cleaner is clean and properly installed.

Clean or replace any damaged or restricted air lines before connecting them to compressor.

Install and tighten compressor mounting bolts.

Align compressor drive.

Connect belt and adjust its tension.

After installation, run the compressor, check and correct any oil or air leaks. Also check for noisy operation.

Disassembly

Clean road dirt and grease from compressor exterior using a good cleaning solvent.

Before disassembling the complete compressor the relationship of several sub-parts should be marked so the compressor can be assembled properly:

The cylinder block in relation to the crankcase,

The cylinder head in relation to the block,

The oil filler plug in relation to the crankcase, if self-lubricated type.

Cylinder Head Figure 10

Remove cap screws and lift off cylinder head cover.

Scrape off cylinder head cover gasket.

Remove discharge valve guides, springs, and discharge valve.

Fig. 10-Exploded View of Cylinder Head

Remove cylinder head body cap screws, then body. It may be necessary to tap cylinder head body with a raw-hide or similar hammer to free it.

Remove inlet valve springs, guides and inlet valve from top of block.

Crankcase Base - Self-Lubricated Type

Remove crankcase base cap screws, then base.

Remove oil pressure check valve from crankcase base.

The oil pump cylinder should not be removed from the base unless it is worn or damaged.

Oil Pump Rod - Self Lubricated Type Figure 11

Fig. 11-Exploded View of Crankcase

Bend back prongs of oil pump rod bolt lockwasher; remove bolts, lockwasher, oil pump rod, and its cap. Reassemble oil pump rod cap to the rod to protect rod bearing.

Remove oil relief valve seat from piston end of oil pump rod. Also remove oil relief ball valve and spring.

Removing And Disassembling Pistons And Connecting Rods

Straighten prongs of connecting rod bolt lockwashers and remove bolts, lockwashers, and bearing caps.

Push pistons with connecting rods attached up and out the top of the cylinder block.

Replace bearing caps on their respective connecting rods.

Remove piston rings from pistons.

If pistons are to be removed from connecting rods, remove wrist pin lock wires and press wrist pins from piston and connecting rods.

Crankcase

Remove cap screws securing end cover at drive end of crankshaft.

Remove end cover with oil seal. Remove or scrape off end cover gasket.

If oil seal needs replacing, it should be removed from end cover.

Remove cap screws that hold opposite end cover to crankcase; remove end cover and its gasket.

Press the crankshaft and ball bearing from the crankcase, then press bearing from crankshaft.

Cylinder Block - Figure 12

Fig. 12-Exploded View of Cylinder Block

If compressor is fitted with an air strainer, inlet fitting or governor, remove same.

Remove cap screws securing cylinder block to crankcase; separate crankcase and cylinder block and scrape off gasket.

Remove unloader spring, spring saddle, and spring seat from cylinder block.

Connect shop air to unloader port and slowly apply air pressure to lift up unloader pistons, guides and plungers. Remove unloader guides and plungers, then unloader pistons.

Inlet valve seats can be removed but only if they are worn or damaged and are being replaced.

Cleaning And Inspection Of Parts Cleaning

All parts should be cleaned thoroughly in a good cleaning solvent before inspection.

Cylinder Head Assembly

Remove any carbon deposits that may have collected on the head discharge cavities or on the cylinder head cover.

The discharge valves, if they are only slightly worn or grooved, can be reclaimed by lapping them on fine crocus cloth (Figure 13), but it is recommended that new valves be used.

Fig. 13-Cleaning Discharge and Intake Valves

Cylinder Block

Clean carbon and dirt from intake and unloader passages. Use air to blow out unloader passages.

Like the discharge valves, the inlet valves can be reclaimed by lapping them on fine crocus cloth, if they are only slightly worn, but it is suggested that new inlet valves be used.

Compressor Oil Passages

Thoroughly clean out oil passages through the crankshaft, connecting rod tops, crankcase, end cover, and base plate. If necessary inspect these passages with a wire, then blow foreign matter out with air pressure.

The crankcase breather of the self-lubricated type should be cleaned thoroughly.

Inspection Of Parts Cylinder Head

Inspect body for cracks or other damage. Discharge valve stops on cylinder cover should not be peened. If the stops are peened excessively, the cylinder head cover should be replaced.

If the discharge valve seats are worn excessively so that there is no longer enough metal left to reclaim them by lapping, the seats or a complete cylinder head body should be replaced.

It is recommended that used discharge valve springs, discharge valve guides and the discharge valve be replaced.

Crankcase And End Covers

Check for cracks or broken lugs in crankcase and end covers. Also check their oil passages to make sure they are open and clean.

Crankcase bearing bore should be checked with cylinder block installed on crankcase. Check fit of ball bearing in its bore. It should be a snug press fit.

Check rear sleeve bearing for scores or damage. It should be a tight press in the crankcase.

Check oil seal of drive end cover for lip wear and flexibility. Replace seal if necessary.

Cylinder Block

Check for cracks or broken lugs on cylinder block.

Check unloader piston bores to be sure they are clean and free of rust.

Check inlet valves. If they are slightly worn or grooved they can be reclaimed by lapping them on a fine piece of crocus cloth, but it is recommended that they be replaced. If the inlet valve seats are worn or damaged excessively and cannot be reclaimed, they should be replaced.

Cylinder Bores

Cylinder bores should not be scored, or be out of round by more than 0.0002", or be tapered more than 0.0003".

The bores must be smooth, straight and round.

Clearance between pistons and cylinder bores should be between .002" minimum and .004" maximum.

Pistons

Check pistons for scores, cracks, or enlarged ring grooves. Replace pistons if any of these conditions are found.

Wrist Pins

Check fit of wrist pins in pistons and in connecting rod bushings; they should be a light press fit. If the wrist pins are loose and worn the wrist pins and pistons should be replaced.

Clearance of the wrist pin in the connecting rod bushing should not exceed 0.0015".

Used wrist pin lock wires should be replaced.

Piston Rings

Check fit of piston rings in piston ring grooves.

Check ring gap with rings installed in cylinder bore. Refer to (Figure 14) for correct gap and groove clearance.

Fig. 14-Location of Piston Ring Groove Clearance

Crankshaft

Check crankshaft screw threads, keyways, tapered ends, and all machined and ground surfaces for wear, scores, cracks, or other damage.

Check oil passages of crankshaft to be sure they are open and clean.

Connecting Rod Bearing

Check fit of connecting rod bearing on crankshaft journals. Worn connecting rods should be replaced.

Connecting rod caps are not interchangeable so they should not be mixed.

The locking slots of the connecting rod and its cap should be positioned adjacent to each other.

Clearance between the connecting rod journals and connecting rod bearings should not be less than 0.0003" or more than 0.0021".

Main Bearings

Check for wear or flat spots on ball bearing and replace if these conditions are found. The rear sleeve bearing should be checked for scores and wear.

Unloader Mechanism

Used unloader parts should be replaced with unloader kit piece number 265013. The new unloader pistons should be a free sliding fit in the unloader piston bores of the cylinder block.

Parts Special To Self-Lubricated Type Compressors

Check fit of oil pump piston in the base plate oil pump bushing to be sure it is a free sliding fit. If excessive clearance is found the oil pump piston and rod, its bushing, or both, should be replaced.

The oil pump relief ball valve seat should be checked for excessive wear. The ball valve should be checked also. If either show excessive wear the oil pump rod should be replaced.

Check the base plate for cracks or other damages, be sure its oil passages are clear and clean.

A new oil pressure check valve should be installed properly in the base plate.

Repairs Discharge Valve And Seats

Fig. 15-Seating Discharge Valve with Dowel

If discharge valve seats merely show signs of slight wear, they can be dressed by using a lapping stone, grinding compound, and lapping tool. New discharge valves and discharge valve springs should be used.

To test for leakage by the discharge valves, apply about 100 pounds of air pressure through the discharge port and check for leakage at the discharge valves and seats. If excessive leakage is found, leave the air pressure applied and with a fibre or hardwood dowel and hammer, tap the discharge valves off their seats several times. (Figure 15). This will coin the valves on their seats and reduce any leakage.

With the air pressure still applied, check for leakage at the cylinder head cover.

Inlet Valves And Seats

Like the case of the discharge valve seats, the inlet seats can be dressed if they show signs of wear. If seats are beyond repair they should be replaced.

It is suggested that new inlet valves and inlet valve spring be used.

Assembly Cylinder Block

Prior to assembly lubricate unloader pistons and piston bores with B-W lubricant, piece number 239379 (dimethyl polysiloxane BW-328-M). If new prelubricated pistons are used, no additional lubricant is necessary.

Install unloader pistons in their bores with caution against cutting the grommets or distorting the back-up rings.

Position unloader plungers in their guides and slip them in over the tops of the pistons.

Install unloader spring seat in the cylinder block.

Position unloader saddle between 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 block and on the saddle.

Position cylinder block gasket and block on crankcase according to markings made prior to disassembly. Install cap screws with lockwashers and tighten block to crankcase.

Installing Crankshaft

Press ball bearing on the crankshaft.

Position ball bearing and crankshaft in crankcase, making sure they are in correct alignment, then carefully press them into the crankcase using an arbor press.

Position and install the rear end cover gasket and end cover with lockwashers and cap screws.

If the front end cover requires an oil seal which was removed on disassembly, a new seal should be pressed into the end cover.

Position a new end cover gasket and carefully install the end cover over the crankshaft and on to the crankcase avoiding damage to the seal.

Secure end cover with cap screw and lockwashers.

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 0.0003" and 0.0008" clearance on the wrist pin.

Position connecting rod in piston and press in wrist pin so that lock wire hole in the pin aligns with that of the piston. Install new lock wires through pistons and wrist pins and lock same by snapping short end into lock wire holes at the piston skirt.

Install piston ring in correct location with pip-marks up. Stagger the position of the ring gaps.

Prelubricate piston, piston rings, wrist pins and connecting rod bearings with clean oil before installing them in the cylinder block.

Remove connecting rod bolts and bearing cap from one connecting rod.

Turn crankshaft so one of its connecting rod journals is in the bottom dead center position. Insert the connecting rod with piston through the top of this cylinder using a piston ring sleeve compresser. Position and attach the related bearing cap to the connecting rod. Follow with the lockwasher and connecting rod bolts. Tighten the connecting rod bolts evenly and then bend up the corners of the lockwasher to lock and hold the bolts.

Install the second connecting rod with piston in the same manner.

Install inlet valve seats if they have been removed. Position and install inlet valve guides then drop inlet valves into their guides. They should be a loose sliding fit between the valve and guide.

Cylinder Head Assembly

If previously removed, the discharge valve seats should be installed in the cylinder head body.

Turn the cylinder head body over and stick the inlet valve spring in the body. It may be necessary to use a small amount of grease to hold the springs in place.

Position the cylinder head gasket and cylinder head body on the cylinder block.

Install cap screws with lockwashers and connect head body to cylinder block.

Install discharge valve guides in proper place in cylinder head. To open sides of the guides should face the discharge port.

Drop discharge valves in the guides and check to be sure they are a loose sliding fit.

Position discharge valve spring on top discharge valves.

Install cylinder head cover making sure discharge valve stops are correctly positioned inside the discharge valve springs.

Install cylinder head cover cap screws and tighten evenly and securely.

Base Plate - Self Lubricated Type Compressors

Position oil relief valve spring and relief ball valve in oil pump piston. Install and tighten relief valve seat until bottomed.

Install oil pump piston bushing in base plate if it was removed on disassembly. Check fit of piston in base plate bushing; the piston must be a medium sliding fit.

Install new oil pressure check valve in base plate properly with check valve and seat down in the plate and the check valve stop pin visible at the top of the plate.

Install oil pump piston and rod on crankshaft. This fit must be the same as specified for connecting rod bearings on crankshaft.

Position base plate gasket on crankcase.

Position base plate assembly on the bottom of the crankcase being sure the oil pump piston engages the oil pump bushing in the base plate and secure plate to crankcase with cap screws and lockwashers.

Install oil dip stick plug in crankcase.

Air Strainer

Assemble the strainer. Use a new strainer gasket and install the strainer on the cylinder block.

Governor - Figure 16

If compressor is type with governor attached, install a new or rebuilt governor to the compressor with the governor mounting bracket. This bracket is secured to the compressor with the cylinder head and block cap screws.

Connect the unloader port of the compressor to the governor unloader port with tubing and fittings.

Fig. 16-Compressor with Governor Attached

Inspection Of Rebuilt Unit

Use covers, plugs, or masking tape to protect all ports if compressor is not to be installed immediately.

Fit the crankshaft end with key, nut, and cotter pin and then protect the end against damage by wrapping with masking or friction tape.

The open bottom of engine lubricated compressors should be protected against the entrance of dirt during handling or storage, by installing a temporary cover over the open base.

Testing Rebuilt Compressor

To properly test a compressor under operating conditions, an elaborate test rack to accommodate 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 simple compressor efficiency and build up test can be run. Before the test is performed, the crankcase of self-lubricated type compressor should be filled with clean lubricating oil. An engine lubricated compressor must be connected to an oil supply line of at least 15 pounds pressure during the test and an oil return must be connected to keep the crankcase drained. The compressor when tested should be less strainer.

To the discharge port of the compressor connect a reservoir or reservoirs whose volume plus the volume of the connecting line equals 1300 cubic inches. Run the compressor between 1700 and 1750 RPM's. Elapsed time that the Tu-Flo 300 type compressor takes to build up from 0 to 100 psi should not exceed 85 seconds.

During this test the compressor should be checked for oil leakage and for noisy operation.