Usage:
Introduction
A Ring.
B Bolt.
1 Thrust rings.
2 Retainer.
3 Thrust bearing.
4 Retainer.
5 Compressor cover.
6 Clamps.
7 Oil cavity vent passage.
8 Shaft.
9 Nozzle.
10 Sleeve.
11 Turbine back plate.
12 Shims.
13 Wear washer.
14 Nut.
15 Turbine housing.
16 Compressor impeller.
17 Turbine wheel.
18 Piston ring seals.
19 Piston ring seals.
20 Oil deflector.
21 Compressor back plate.
22 Seal.
23 Bearing housing.
24 Oil drain hole.
25 Bearings.
26 Oil thrower.
TURBOCHARGER
The turbocharger is designed to increase the diesel engine power output. The turbocharger absorbs energy from the diesel exhaust gases, and uses this energy to drive the compressor impeller (16) for supercharging the diesel engine.
The turbocharger is comprised of a turbine wheel (17) and a compressor impeller (16) on a rotating shaft (8), a bearing housing (23), a turbine housing (15), compressor cover (5), and a compressor back plate (21).
The turbine wheel is located in the turbine housing and is permanently secured to one end of the shaft. The impeller is secured to the other end of the shaft by a nut (14) to form an integral rotating assembly. To assure reliability and freedom from vibration, all parts of the rotating assembly have been carefully dynamically balanced.
The bearing housing (23) encloses and supports the rotating assembly and contains the oil inlet hole and oil outlet hole. The turbine housing and compressor cover are mounted to the bearing housing and secured in position by the clamps (6).
NOTE: Some models secure the compressor cover to the bearing housing by means of a ring (A) and bolts (B) rather than the clamp (6).
A tube, one end of which is connected to the crankcase, is connected to the oil cavity vent passage (7). Venting this area promotes the draining of the oil from the bearing housing, and therefore away from the seals, thus reducing the work-load imposed on the seals.
NOTE: Some earlier engines have a breather connected to the passage (7) instead of the vent tube.
The rotating assembly is supported by two full floating pressure lubricated bearings (25) located in the bearing housing. Filtered engine oil is supplied to the bearings through passages in the housing in sufficient quantity to lubricate the shaft bearings (25) and thrust bearing (3). This oil also aids in the removal of excessive heat. Oil returns from the turbocharger to the crankcase through an external tube at (24). Thrust loads are absorbed by the stationary thrust bearing (3) and the rotating thrust rings (1). The oil deflector (20) contains and routes the oil thrown from the shaft and thrust rings back to the drain opening (24).
Piston rings (18) and (19) on either end of the shaft prevent oil from escaping the bearing housing.
The turbine housing, besides housing the turbine wheel, acts as a chamber for the exhaust gases from the diesel engine. The gases are directed through the turbine housing and into contact with the turbine blades by the nozzle (9). Different nozzles are used for different engine applications. For the correct nozzle, see the Rack Setting Charts.
Shims (12) are located between the impeller (16) and the sleeve (10) making it possible to adjust the impeller-to-cover clearance.
The turbocharger is mounted on the exhaust outlet of the diesel engine exhaust manifold. The exhaust gases from the diesel engine pass through the turbine end of the turbocharger before they are discharged into the atmosphere. This flow of exhaust gases through the turbine wheel provides the energy to operate the turbocharger.
During operation, the turbocharger responds to the engine load demands by reacting to the flow of exhaust gases and the corresponding demand of the engine for air.
The exhaust gases enter the turbine housing (15) at the exhaust inlet opening and are directed through the vanes of the nozzle (9) into contact with the blades of the turbine wheel (17). The exhaust provides the driving force to turn the turbine wheel and the impeller (16).
The turbocharger should always be handled carefully to avoid damage to any of its components.
Altitude Operation
The maximum turbocharger speed is determined by the rack setting, the high idle speed setting, the pressure ratio control setting, on engines so equipped, and the altitude at which the engine is operated. The rack setting has been set to permit the engine to be operated at the altitude given on the warning plate on the instrument panel or valve cover. The high idle speed setting is not the same for all altitudes. If the high idle speed or the rack setting is greater than specified for the altitude at which the engine is operated, serious damage to engine or turbocharger parts may result.
The maximum altitude at which the engine can be operated is specified on the altitude warning plate located on the valve cover or instrument panel. The governor housing and turbocharger are sealed to prevent serious engine damage or personal injury due to operation of the engine with incorrect settings or turbocharger nozzle. Changes to the turbocharger, rack setting, or high idle speed should be made only by a Caterpillar dealer serviceman.
The engine can be operated at a lower altitude than specified on the warning plate without danger of engine damage, but with slightly less than maximum performance. When operated at a higher altitude, the rack setting and high idle speed setting must be changed only by a Caterpillar dealer serviceman. After making any changes, the new altitude limit should be stamped on the altitude warning plate.
Also, the new high idle, full load speed, and rack setting should be stamped on the governor warning plate. Reseal the governor housing for continued protection.
Sealing Of The Turbocharger
The turbocharger is sealed at the factory as shown at (1). Factory installed seals are identified by the letters CT CO. Dealer's sealing tool, will impress the letters DLR on the seals.
TURBOCHARGER FACTORY SEAL
1-Seal.
Checking Bearing Clearance
A quick check of bearing condition can be made without disassembling the turbocharger. This can be done by inspecting the compressor impeller, turbine wheel, turbine housing and compressor cover. If there is no indication of either the impeller rubbing the compressor cover or the turbine wheel rubbing the turbine housing, the bearing clearances are generally satisfactory.
A more reliable check of bearing condition can be made only when the turbocharger is disassembled and the bearings, shaft journal and housing bore diameters can actually be measured. See the SPECIFICATIONS for these diameters.
While the turbocharger is disassembled, carefully check the back surfaces of the compressor impeller and turbine wheel for signs of contact with the cover or housing. Contact in these areas would indicate a worn thrust bearing or thrust rings.
Checking Turbocharger Shaft End Clearance
See the SPECIFICATIONS for normal and permissible shaft end clearance (axial movement). End clearance is checked with a dial indicator, either on or off the engine. If permissible clearance is exceeded, recondition the turbocharger.
Disassembly Of The Turbocharger
Compressor Cover and Turbine Housing Removal and Installation
1. Cover all turbocharger openings and wash the exterior thoroughly with nonflammable fluid before disassembly.
2. Mark compressor cover (1), turbine housing (6) and bearing housing (2), prior to disassembly, to insure correct positioning upon assembly.
NOTE: On some models, clamp (3) is replaced by ring (A) which fits into a groove in compressor cover (1) and is secured to bearing housing (2) by bolts. It is necessary on these models, to remove the bolts and ring prior to removing the compressor cover. Upon assembly it will also be necessary to cement the side of a new gasket (B) to the bearing housing. Tighten the bolts to the torque value in the SPECIFICATIONS.
PREPARING TO REMOVE COMPRESSOR COVER AND TURBINE HOUSING
A-Ring. B-Gasket. 1-Compressor cover. 2-Bearing housing. 3-Clamp. 4-Seal. 5-Clamp. 6-Turbine housing.
| NOTICE |
|---|
Use caution when removing the turbine housing. Turbine nozzle (8) is a loose fit on turbine back plate (7). |
3. Lift nozzle (8) from turbine back plate (7).
REMOVING NOZZLE
2-Bearing housing. 7-Turbine back plate. 8-Nozzle.
4. Before installing the compressor cover and turbine housing, see the topic CLEANING AND INSPECTION.
5. Complete the assembly. Turn the impeller by hand to be certain there is no rubbing or binding within the turbocharger.
Rotating Parts
Before disassembly of the rotating assembly, measure the shaft end clearance as previously described. If the clearance is excessive, or if either the turbine wheel or impeller has rubbed against the housing or cover, the bearings and/or thrust bearing and thrust rings must be replaced. Bent impeller blades require replacement of the entire rotating assembly. Turbine blades, which are noticeably bent also require replacement of the rotating assembly.
Bearing failure can damage the shaft journals and/or thrust bearing or rings. Excessive wear or roughness renders the shaft unsuitable for reuse. If the shaft journals measure less than the specified diameter, a new rotating assembly should be installed. Visual inspection and experience are the only ways to determine when the roughness of the shaft prohibits reusing the rotating assembly. New bearings will not correct excessive wear on the thrust bearing or thrust rings.
Installing new bearings does not eliminate the necessity of inspecting and cleaning the rotating parts.
1. Assemble fixture adapter (2) to fixture (4). Place bearing housing (1), containing the rotating parts, on the fixture adapter with the turbine wheel down as illustrated.
FIXTURE
2. Before removing the impeller, make sure the alignment marks on the impeller and the shaft are visible, since all rotating parts are rematched during reassembly to maintain the previously established dynamic balance of the unit.
NOTE: Later rotating parts are balanced and no alignment is necessary.
3. Remove the nut. The rotating assembly can be held stationary by using wrench (3).
FIXTURE ADAPTER
WRENCH
| NOTICE |
|---|
Take care to prevent any distortion of the blades. |
REMOVING NUT
1-Bearing housing. 2-Fixture adapter. 3-Wrench. 4-Fixture.
SUPPORTING SCREW
4. Thread supporting screw (5) into the base of the fixture to contain the turbine wheel and shaft when pressed from the impeller. Leave a space between the end of the screw and the turbine wheel equal to or slightly greater than the thickness of the impeller. This will allow an unobstructed pressing action on the shaft and still prevent the turbine wheel from being damaged by striking against the fixture base.
5. Using a press and a pin, press the shaft and turbine wheel from the impeller hub as shown.
PRESSING SHAFT AND TURBINE WHEEL FROM IMPELLER
5-Supporting screw.
6. Remove the impeller and the shims from beneath the impeller.
7. Back off screw (5) and remove bearing housing from the fixture to allow the removal of the turbine wheel and shaft.
8. Measure the shaft journal diameters and inspect the journals for roughness. If the journal diameters are less than specified, the rotating assembly must be replaced. See the SPECIFICATIONS for correct dimensions.
9. Inspect the piston ring-type seals and measure the thickness. Measure the width of the seal grooves. See the SPECIFICATIONS.
Bearing Housing
REMOVING TURBINE BACK PLATE
1-Back plate. 2-Snap ring. 3-Bolts (five).
1. Separate bearing housing (4) from compressor back plate (6) and remove O-ring seal (5).
SEPARATING HOUSING AND PLATE
4-Bearing housing. 5-O-ring seal. 6-Compressor back plate.
DISASSEMBLING COMPRESSOR BACK PLATE
6-Compressor back plate. 7-Piston ring-type seals. 8-Sleeve.
OIL DEFLECTOR REMOVAL
4-Bearing housing. 9-Bolts. 10-Oil deflector.
2. Inspect piston ring-type seals (7) and measure the thickness. Measure the width of the seal groove. See the SPECIFICATIONS.
THRUST BEARING REMOVAL
11-Oil retainer. 12-Thrust ring. 13-Thrust bearing. 14-Spacer. 15-Thrust r ring. 16-Oil retainer.
3. Remove the outboard snap ring, wear washer, bearing (17) and inboard snap ring (19) from bearing housing (4).
NOTE: When assembling, position the wear washer between bearing (17) and outboard snap ring.
BEARING REMOVAL
4-Bearing housing. 17-Bearing. 18-Bearing. 19-Inboard snap ring. 20-Snap ring.
4. Inspect and measure thrust rings (12) and (15), thrust bearing (13), the bore in bearing housing (4), the wear washer and bearings (17) and (18). See the SPECIFICATIONS.
NOTE: When bearings (17) and (18) do not measure up to SPECIFICATIONS, install new bearings. Bearings can be serviceable even though the plating is worn off.
5. Replace any worn or damaged parts.
Cleaning And Inspection
Inspect rotating parts for binding and damage caused by rubbing on adjacent parts. Replace any damaged parts if any of these symptoms are present.
Wash all parts with cleaning solvent and dry thoroughly. Use wood to clean the carbon and deposits from the turbine housing and the nozzle.
The turbine wheel must be cleaned with a good cleaning solvent in order to dissolve the carbon. The amount of soaking depends on the amount and type of deposits on the wheel. When hard carbon deposits are formed, soaking in solvent-type cleaner for an hour or more is required. The loosened particles must all be scraped off with a stiff brush or a specially shaped piece of wood and, if necessary, the whole process repeated. If the wheel is covered with soot only, washing with a stiff brush and cleaning solvent and then rinsing with clean water will be sufficient.
| NOTICE |
|---|
The rotating components must be thoroughly cleaned in order to maintain the critical balance of the unit. Do not use a wire brush or wheel. |
Assembling Turbocharger
Before assembling, be certain all parts are thoroughly clean. Extreme care must be taken to keep out dirt and foreign material.
Bearing Housing
Install snap rings (4), wear washer (1) and bearings (3) in bearing housing (2).
Later bearing (3) at the compressor end of the housing (2) has grooves in the bore of the bearing.
| NOTICE |
|---|
Exercise extreme care during installation of snap rings (4) to prevent scratching the bearing housing bore. Each snap ring must be installed with the flat side facing the bearing for which it is acting as a retainer. Lubricate the bearings prior to installation. |
Install back plate (5) on bearing housing (2) and secure in place with snap ring (6).
BEARING INSTALLATION
1-Wear washer. 2-Bearing housing. 3-Bearings. 4-Snap rings.
NOTE: Beveled-type snap ring (6) must be installed with the flat side toward the back plate. Make certain the ring is secure in the groove.
BACK PLATE INSTALLATION
2-Bearing housing. 5-Back plate. 6-Snap ring.
Rotating Parts
1. Lubricate the piston ring-type seal grooves and, with the aid of fabricated ring expander sleeve (1), install the two piston ring-type seals on the shaft.
DETAIL FOR FABRICATING RING EXPANDER SLEEVE
2. Remove the sleeve and rotate the rings until the gaps are 180° apart.
INSTALLING PISTON RING SEAL
1-Ring expander sleeve.
3. Center the ring seals on the shaft with the gaps 180° apart and insert the shaft into the turbine end of the bearing housing. If the rings do not enter the housing easily, remove the shaft and re-center the rings.
4. Place bearing housing (2) and shaft (3) on the fixture (4), with the aid of fixture adapter (5), and support the shaft with support screw (6).
SHAFT INSTALLATION
2-Bearing housing. 3-Shaft. 4-Fixture. 5-Fixture adapter. 6-Support screw.
5. Install oil retainer (10), thrust ring (9), spacer (8) and thrust bearing (7).
NOTE: The bolt holes in the oil retainer and thrust bearing are staggered to eliminate the possibility of installing these items incorrectly.
INSTALLING THRUST BEARING
7-Thrust bearing. 8-Spacer. 9-Thrust ring. 10-Oil retainer.
6. Install thrust ring (12) and oil retainer (11).
INSTALLING OIL RETAINER
11-Oil retainer. 12-Thrust ring.
7. Install oil deflector (17) and bolts (16). Bend the locks to secure the bolts in place.
8. Slip sleeve (15) over the shaft so the end containing the piston ring-type seal groove faces away from the bearing housing.
9. If sleeve (15) has an interference fit on the shaft, heat the sleeve in oil at 250° F. for a few minutes to facilitate installation. Allow sleeve to cool before tightening the impeller retaining nut.
NOTE: If the piston ring-type seals were removed from the sleeve (15), it will be necessary to install them again upon installation of the sleeve. If the rings were not removed, the sleeve and rings can be installed as a unit.
10. Lubricate the rings and rotate them until their gaps are 180° apart.
INSTALLING COMPRESSOR BACK PLATE
13-Compressor back plate. 14-O-ring seal. 15-Sleeve. 16-Bolts (three). 17-Oil deflector.
11. Install O-ring seal (14) in the groove provided in compressor back plate (13) and place the back plate over the shaft, carefully lowering it to the assembled position. Tighten the bolts securing the back plate in this position. See the SPECIFICATIONS.
| NOTICE |
|---|
Use care to prevent ring breakage when seating ring seals in the compressor back plate bore. Do not force the rings into the bore. |
SPACER BLOCK
12. Place the approximate amount of shims needed on the shaft. Install spacer block (19) and nut (18). Tighten the nut to the specified torque.
13. Using a thickness gauge (20) on each side of the spacer block as illustrated, check the impeller-to-compressor back plate clearance. Measure with the block pushed toward the impeller end. This clearance is regulated by the shims under the impeller; add or remove shims as required. See the SPECIFICATIONS for correct clearance.
CHECKING IMPELLER TO HOUSING CLEARANCE
18-Nut. 19-Spacer block. 20-Thickness gauges.
14. Remove nut (18) and spacer block (19).
15. Carefully install the impeller on the shaft.
NOTE: Make certain the support screw pushes the shaft firmly toward the impeller end during this operation. Also make certain the impeller bottoms on the shaft.
16. Install a new nut and tighten to the torque value specified in the SPECIFICATIONS.
INSTALLING NUT
17. Recheck the impeller-to-back plate clearance by placing the appropriate thickness gauge under the impeller wheel. Also check again for proper end clearance.
18. Make a final inspection to determine if any blades have been accidentally damaged or bent during the assembly operation.
19. Install the nozzle, turbine housing and compressor cover.