Introduction

NOTE: For Specifications with illustrations, make reference to SPECIFICATIONS for 3408 & 3408B INDUSTRIAL AND MARINE ENGINES, Form No. SENR7380. If the Specifications in Form SENR7380 are not the same as in the Systems Operation and the Testing and Adjusting, look at the printing date on the back cover of each book. Use the Specifications given in the book with the latest date.

Engine Design

CYLINDER, VALVE AND INJECTION PUMP LOCATION

Bore ... 137.2 mm (5.40 in.)

Stroke ... 152.4 mm (6.00 in.)

Number and Arrangement of Cylinders ... V-8

Firing Order (Injection Sequence) ... 1, 8, 4, 3, 6, 5, 7, 2

Rotation of Crankshaft (when seen from flywheel end) ... counterclockwise

Rotation of Fuel Pump Camshaft (when seen from pump drive end) ... counterclockwise

NOTE: Front end of engine is opposite to flywheel end. Left side and right side of engine are as seen from flywheel end. No. 1 cylinder is the front cylinder on the left side. No. 2 cylinder is the front cylinder of the right side.

Fuel System

This engine has a pressure type fuel system. There is one injection pump and one injection valve for each cylinder. The injection pumps are in injection pump housing (4) on the top of the engine. The injection valves are in the precombustion chambers or adapters (for engines with direct injection) under the valve covers.

Fuel is pulled from fuel tank (6) through primary fuel filter (8) by fuel transfer pump (9). The transfer pump sends fuel through main fuel filter (11) to the manifold of the fuel injection pump housing.

Fuel in the manifold of the injection pump housing is the supply for the injection pumps. Some of the fuel in the manifold is constantly sent through an orifice in the tee or fitting that connects the return line to the manifold. The orifice controls the pressure in the manifold and the amount of fuel that returns to the tank. The constant flow of fuel back to the tank removes air from the system.

FUEL SYSTEM SCHEMATIC
1. Fuel inlet line for the injection pump housing. 2. Damper. 3. Adapter with orifice. 4. Injection pump housing. 5. Fuel return line. 6. Fuel tank. 7. Fuel supply lines. 8. Primary fuel filter. 9. Fuel transfer pump. 10. Fuel priming pump. 11. Main fuel filter.

LOCATION OF FUEL SYSTEM COMPONENTS
1. Fuel inlet line for the injection pump housing. 2. Damper. 3. Adapter with orifice. 4. Injection pump housing. 5. Fuel return line. 7. Fuel supply line. 9. Fuel transfer pump. 12. Nut for a fuel injection line at the injection pump. 13. Fuel manifold across the injection pump housing. 14. Adapter through the valve cover base. 15. Governor.

There is a surge damper (2) in the system to reduce shock loads on the fuel filter caused by high pressure from the injection pumps. On later engines, damper (2) is installed on the outlet side of fuel manifold (13). On earlier engines, damper (2) is installed on the inlet side of fuel manifold (13).

The injection pumps are in time with the engine. They send fuel to the injection valves under high pressure. When the fuel pressure at the injection valve is high enough the valve opens and sends fuel into the precombustion chamber or directly into the cylinder on direct injection engines.

Fuel transfer pump (9) has a bypass valve and a pressure relief valve. The bypass valve makes it possible for the priming pump to send fuel through the transfer pump. The pressure relief valve controls the maximum pressure of the fuel. When the pressure gets too high the valve opens and some of the fuel goes back to the inlet side of the pump.

When there is air on the inlet side of the fuel system use priming pump (10). Operation of the priming pump fills the system with fuel. This forces the air back into the tank.

Air can be removed from the fuel injection lines by loosening a fuel injection line nut (one at a time) at the valve cover base adapter. On PC Engines use the priming pump to remove the air. On DI Engines use the starter motor to turn the engine until fuel without air flows from the loosen nut. Tighten the nuts after air has been removed.

NOTE: Because of the check assemblies in the injection pump outlets for the DI engine, the priming pump will not give enough pressure to remove air from the fuel injection lines.

LOCATION OF FUEL SYSTEM COMPONENTS
1. Fuel inlet line to injection pump housing. 5. Fuel return line to tank. 7. Fuel supply line. 10. Fuel priming pump. 11. Main fuel filters. 16. Junction block. 17. Fuel outlet line from transfer pump and inlet line to main filters.

Fuel Injection Pump

CROSS SECTION OF THE FUEL INJECTION PUMP HOUSING
1. Fuel manifold. 2. Inlet passage. 3. Check valve. 4. Pressure relief passage. 5. Pump plunger. 6. Spring. 7. Gear. 8. Fuel rack (left). 9. Lifter. 10. Link. 11. Lever. 12. Camshaft.

The rotation of the cams on the camshaft (12) cause lifters (9) and pump plungers (5) to move up and down. The stroke of each pump plunger is always the same. The force of springs (6) hold lifters (9) against the cams of the camshaft.

The pump housing is a "V" shape (similar to the engine cylinder block), with four pumps on each side.

When the pump plunger is down, fuel from fuel manifold (1) goes through inlet passage (2) and fills the chamber above pump plunger (5). As the plunger moves up it closes the inlet passage.

The pressure of the fuel in the chamber above the plunger increases until it is high enough to cause check valve (3) to open. Fuel under high pressure flows out of the check valve through the fuel line to the injection valve until the inlet passage opens into pressure relief passage (4) in the plunger. The pressure in the chamber decreases and check valve (3) closes.

The longer the inlet passage is closed the larger the amount of fuel which will be forced through check valve (3). The period for which the inlet passage is closed is controlled by the pressure relief passage. The design of the passage makes it possible to change the inlet passage closed time by rotation of the plunger. When the governor moves fuel racks (8) they move gears (7) that are fastened to plungers (5). This causes a rotation of the plungers.

The governor is connected to the left rack. The spring load on lever (11) removes the play between the racks and link (10). The fuel racks are connected by link (10). They move in opposite directions (when one rack moves in, the other rack moves out).

Fuel Injection Valves (On Earlier Engines)

The fuel injection valves are installed in the precombustion chambers in engines equipped with precombustion chambers. An adapter takes the place of the precombustion chamber in engines equipped with direct injection. The precombustion chambers or adapters are installed in the cylinder heads.

Fuel, under high pressure from the injection pumps, is sent through the injection lines to the injection valves. The injection valves change the fuel to a fine spray for good combustion in the cylinders. The injection valves will not open until the fuel in the injection lines reaches a very high pressure. The valves then open quickly to release the fuel directly into the engine cylinder through orifices in the tip of each nozzle.

Fuel Injection Nozzles (On Later DI Engines)

The fuel injection nozzle is installed in an adapter in the cylinder head and is extended into the combustion chamber. The fuel injection pump sends fuel with high pressure to the fuel injection nozzle where the fuel is made into a fine spray for good combustion.

FUEL INJECTION NOZZLE
1. Carbon dam. 2. Seal. 3. Passage. 4. Filter screen. 5. Inlet passage. 6. Orifice. 7. Valve. 8. Diameter. 9. Spring.

Seal (2) goes against the nozzle adapter and prevents leakage of compression from the cylinder. Carbon dam (1) keeps carbon out of the bore in the nozzle adapter.

Fuel with high pressure from the fuel injection pump goes into inlet passage (5). Fuel then goes through filter screen (4) and into passage (3) to the area below diameter (8) of valve (7). When the pressure of the fuel that pushes against diameter (8) becomes greater than the force of spring (9), valve (7) lifts up. This occurs when the fuel pressure goes above the Valve Opening Pressure of the fuel injection nozzle. When valve (7) lifts, the tip of the valve comes off of the nozzle seat and the fuel will go through the six small orifices (6) into the combustion chamber.

The injection of fuel continues until the pressure of fuel against diameter (8) becomes less than the force of spring (9). With less pressure against diameter (8), spring (9) pushes valve (7) against the nozzle seat and stops the flow of fuel to the combustion chamber.

The fuel injection nozzle can not be disassembled and no adjustments can be made.

Hydra-Mechanical Governors

The governor controls the amount of fuel needed to keep a desired engine rpm over the complete engine speed range. The governor automatically makes up for variable engine loads to maintain a constant engine rpm.

The earlier and later governor operate the same. The earlier governors have two levers (13) and the later governors have a one piece lever (13). The shutoff solenoid and fuel ratio control have been moved from the injection pump housing to the governor housing on the later governors.

When the engine is operating, the balance between the centrifugal force of the governor weights and the force of the governor control on the governor spring, controls the movement of a valve and indirectly, the fuel rack. The valve directs pressure oil to either side of a rack positioning piston. Depending on the position of the valve, the rack is moved to increase and decrease the fuel to the engine to compensate for load variation.

HYDRA-MECHANICAL GOVERNOR WITH DASHPOT
1. Collar. 2. Collar bolt. 3. Dashpot chamber. 4. Dashpot piston. 5. Lever assembly. 6. Dashpot spring. 7. Governor spring. 8. Governor weights. 9. Valve. 10. Cylinder. 11. Drive assembly. 12. Pin. 13. Lever.

The governor has governor weights (8) driven by the engine through the drive assembly (11). The governor has a governor spring (7), valve (9) and a piston. The valve and piston are connected to one fuel rack through pin (12) and lever (13).

The governor control, is connected to the governor control lever and controls only the compression of governor spring (7). Compression of the spring always pushes down to give more fuel to the engine. The centrifugal force (rotation) of governor weights (8) always pulls up to get a reduction of fuel to the engine. When these two forces are in balance, the engine runs at the desired rpm (governed rpm).

The governor oil pump on top of the fuel injection pump housing sends engine oil under pressure to governor cylinder (10) through passage (18) around sleeve (19).

GOVERNOR IN INCREASED LOAD POSITION
7. Governor spring. 8. Governor weights. 9. Valve. 10. Cylinder. 12. Pin. 14. Oil drain passage for piston. 15. Upper oil passage in piston. 16. Piston. 17. Lower oil passage in piston. 18. Oil passage in cylinder. 19. Sleeve.

When the load on the engine increases, the engine rpm decreases and the rotation of governor weights (8) will get slower. The governor weights will move toward each other. Governor spring (7) moves valve (9) to open the oil passages in piston (16) and close oil drain passage (14). This lets the oil flow from passage (17), around valve (9), and through passage (15) to fill the chamber above piston (16). This pressure oil pushes piston (16) and pin (12) down to give more fuel to the engine. Engine rpm increases until the rotation of the governor weights is fast enough to be in balance with the force of the governor spring.

When there is a reduction in load on the engine, there will be an increase in engine rpm and the rotation of governor weights (8) will get faster. This will move valve (9) up. This stops oil flow from passage (17) and oil pressure above piston (16) goes out around valve (9) through the top of piston (16). Now, the pressure between sleeve (19) and piston (16) pushes the piston and pin (12) up. This causes a reduction in the amount of fuel to the engine. Engine rpm decreases until the centrifugal force (rotation) of the governor weights is in balance with the force of the governor spring. When these two forces are in balance, the engine will run at the desired rpm (governed rpm).

GOVERNOR IN DECREASED LOAD POSITION
7. Governor spring. 8. Governor weights. 9. Valve. 10. Cylinder. 12. Pin. 14. Oil drain passage for piston. 15. Upper oil passage in piston. 16. Piston. 17. Lower oil passage in piston. 18. Oil passage in cylinder. 19. Sleeve.

When the engine rpm is at LOW IDLE, a spring loaded plunger in lever assembly (5) is in contact with a shoulder on the adjustment screw for low idle. To stop the engine, move the switch to the "OFF" position. This will cause the shutoff solenoid to move the spring loaded plunger over the shoulder on the low idle adjustment screw and move the fuel racks to the fuel shutoff position. With no fuel to the engine cylinders, the engine will stop. On later engines, to stop the engine manually, turn the shutoff lever on the governor housing to the shutoff position. On earlier engines, to stop the engine manually, pull back on the governor control.

Oil from the governor pump gives lubrication to the governor weight support (with gear), thrust bearing (under the governor spring), and drive gear bearing. The other parts of the governor get lubrication from "splash-lubrication" (oil thrown by other parts). Oil from the governor runs down into the housing for the fuel injection pumps.

Some engines need a governor that has better control over the engine speed range than a standard hydra-mechanical governor gives. A piston (4) and spring (6) around bolt (2), plus an oil reservoir in the shutoff housing (adapter), and two adjustment screws (20 and 21) are added to the basic hydra-mechanical governor. These parts control the flow of oil into and out of dashpot chamber (3) above piston (4), through internal oil passages. With correct oil flow into and out of dashpot chamber (3), the lower governor spring seat moves with more precision and the governor gives better control of the engine speed.

SIDE VIEW OF GOVERNOR
20. Adjustment screw for dashpot. 21. Adjustment screw for supply oil to reservoir.

The oil for the dashpot action comes from the engine lubrication system. Adjustment screw (21) controls the oil flow from the lubrication system into the reservoir, which has an overflow outlet back to the mechanical area of the governor. On earlier engines, adjustment screw (21) is located on top of the governor housing. Too much oil flow to the reservoir will fill the governor with oil and decrease engine performance. Too little oil flow does not give enough oil to reservoir. Now the governor will hunt (increase and decrease engine speed constantly) as air gets into dashpot chamber (3) and lets piston (4) and the lower governor spring seat move faster.

Dashpot adjustment screw (20) causes a restriction to oil flow into and out of dashpot chamber (3). Too much oil flow lets the lower governor spring seat move faster, and the governor will hunt. Too little oil flow will cause slow governor action.

Automatic Timing Advance Unit

The automatic timing advance unit is installed on the front of the camshaft (6) for the fuel injection pump and is gear driven through the timing gears. The drive gear (5) for the fuel injection pump is connected to the camshaft (6) through a system of weights (2), springs (3), slides (4) and a flange (1). Each one of the two slides (4) is held on the gear (5) by a pin. The two weights (2) can move in guides inside the flange (1) and over the slides (4), but the notch for the slide in each weight is at an angle with the guides for the weight in the flange. As centrifugal force (rotation) moves the weights away from the center, against springs (3), the guides in the flange and the slides on the gear make the flange turn a little in relation to the gear. Since the flange is connected to the camshaft for the fuel injection pump, the fuel injection timing is also changed.

There is no adjustment for the timing advance unit.

AUTOMATIC TIMING ADVANCE UNIT
1. Flange. 2. Weight. 3. Springs. 4. Slide. 5. Drive gear. 6. Camshaft.

Fuel Ratio Control

FUEL RATIO CONTROL (Engine Stopped)
1. Inlet air chamber. 2. Valve. 3. Diaphragm assembly. 4. Oil drains. 5. Pressure oil chamber. 6. Large oil passages. 7. Oil inlet. 8. Small oil passages. 9. Oil outlet. 10. Fuel rack linkage. 11. Valve.

With the engine stopped, valve (11) is in the fully extended position. The movement of fuel rack linkage (10) is not limited by valve (11).

When the engine is started oil flows through oil inlet (7) into pressure oil chamber (5). From chamber (5) the oil flows through large oil passages (6), inside valve (11), and out small oil passages (8) to oil outlet (9).

A hose assembly connects inlet air chamber (1) to the inlet air system. As the inlet air pressure increases it causes diaphragm assembly (3) to move down. Valve (2), that is part of the diaphragm assembly, closes large and small oil passages (6 and 8). When these passages are closed oil pressure increases in chamber (5). This increase in oil pressure moves valve (11) up. The control is now ready for operation.

FUEL RATIO CONTROL (Ready for operation)
1. Inlet air chamber. 2. Valve. 5. Pressure oil chamber. 6. Large oil passages. 8. Small oil passages. 11. Valve.

When the governor control is moved to increase fuel to the engine, valve (11) limits the movement of fuel rack linkage (10) in the "Fuel On" direction. The oil in chamber (5) acts as a restriction to the movement of valve (11) until inlet air pressure increases.

As the inlet air pressure increases, valve (2) moves down and lets oil from chamber (5) drain through large oil passages (6) and out through oil drains (4). This lets valve (11) move down so fuel rack linkage (10) can move gradually to increase fuel to the engine. The control is designed not to let the fuel increase until the air pressure in the inlet manifold is high enough for complete combustion. It prevents large amounts of exhaust smoke caused by an air-fuel mixture with too much fuel.

The control movements take a very short time. No change in engine acceleration (rate at which speed increases) can be felt.

FUEL RATIO CONTROL (Increase in inlet air pressure)
2. Valve. 4. Oil drains. 5. Pressure oil chamber. 10. Fuel rack linkage. 11. Valve.

Woodward PSG Governors

SCHEMATIC OF PSG GOVERNOR
1. Return spring. 2. Output shaft. 3. Output shaft lever. 4. Strut assembly. 5. Speeder spring. 6. Power piston. 7. Flyweights. 8. Needle valve. 9. Thrust bearing. 10. Pilot valve compensating land. 11. Buffer piston. 12. Pilot valve. 13. Pilot valve bushing. 14. Control ports. A. Chamber. B. Chamber.

Introduction

The Woodward PSG (Pressure compensated Simple Governor) can operate as an isochronous or a speed droop type governor. It uses engine lubrication oil, increased to a pressure of 1200 kPa (175 psi) by a gear type pump inside the governor, to give hydra/mechanical speed control.

Pilot Valve Operation

A gear on the rear of the fuel injection pump camshaft drives a vertical pinion shaft. The pinion shaft turns pilot valve bushing (13) counterclockwise, as seen from the drive unit end of the governor. The pilot valve bushing is connected to a spring driven ballhead. Flyweights (7) are fastened to the ballhead by pivot pins. The centrifugal force caused by the rotation of the ballhead causes the flyweights to pivot out. This action of the flyweights changes the centrifugal force to axial force against speeder spring (5). There is a thrust bearing (9) between the toes of the flyweights and the seat for the speeder spring. Pilot valve (12) is fastened to the seat for the speeder spring. Movement of the pilot valve is controlled by the action of the flyweights against the force of the speeder spring.

The engine is at the governed (desired) rpm when the axial force of the flyweights is the same as the force of compression in the speeder spring. The flyweights will be in the position shown. Control ports (14) will be closed by the pilot valve.

Fuel Increase

When the force of compression in the speeder spring increases (operator increases desired rpm) or the axial force of the flyweights decreases (load on the engine increases) the pilot valve will move in the direction of the drive unit. This opens control ports (14). Pressure oil flows through a passage in the base to chamber (B). The increased pressure in chamber (B) causes power piston (6) to move. The power piston pushes strut assembly (4), which is connected to output shaft lever (3). The action of the output shaft lever causes clockwise rotation of output shaft (2). This moves the fuel control linkage (15) in the FUEL ON direction.

PSG GOVERNOR INSTALLED
2. Output shaft. 15. Fuel control linkage.

As the power piston moves in the direction of return spring (1) the volume of chamber (A) increases. The pressure in chamber (A) decreases. This pulls the oil from the chamber inside the power piston, above buffer piston (11) into chamber (A). As the oil moves out from above buffer piston (11) to fill chamber (A), the buffer piston moves up in the bore of the power piston. Chambers (A and B) are connected respectively to the chambers above and below the pilot valve compensating land (10). The pressure difference felt by the pilot valve compensating land adds to the axial force of the flyweights to move the pilot valve up and close the control ports. When the flow of pressure oil to chamber (B) stops, so does the movement of the fuel control linkage.

Fuel Decrease

When the force of compression in the speeder spring decreases (operator decreases desired rpm) or the axial force of the flyweights increases (load on the engine decreases) the pilot valve will move in the direction of speeder spring (5). This opens control ports (14). Oil from chamber (B) and pressure oil from the pump will dump through the end of the pilot valve bushing. The decreased pressure in chamber (B) will let the power piston move in the direction of the drive unit. Return spring (1) pushes against strut assembly (4). This moves output shaft lever (3). The action of the output shaft lever causes counterclockwise rotation of output shaft (2). This moves fuel control linkage (15) in the FUEL OFF direction.

EARLIER PSG GOVERNOR
6. Power piston. 8. Needle valve. 10. Pilot valve compensating land. 11. Buffer piston. 14. Control ports. A. Chamber. B. Chamber.

As power piston (6) moves in the direction of the drive unit the volume of chamber (A) decreases. This pushes the oil in chamber (A) into the chamber above buffer piston (11). As the oil from chamber (A) flows into the power piston, it moves the buffer piston down in the bore of the power piston. The pressure at chamber (A) is more than the pressure at chamber (B). Chambers (A and B) are connected respectively to chambers above and below the pilot valve compensating land (10). The pressure difference felt by the pilot valve compensating lands adds to the force of the speeder spring to move the pilot valve down and close the control ports. When the flow of oil from chamber (B) stops, so does the movement of the fuel control linkage.

Hunting

There is a moment between the time the fuel control linkage stops its movement and the time the engine actually stops its increases or decrease of rpm. During this moment there is a change in two forces on the pilot valve, the pressure difference at the pilot valve compensating land and the axial force of the flyweights.

The axial force of the flyweights changes until the engine stops its increase or decrease of rpm. The pressure difference at the pilot valve compensating land changes until the buffer piston returns to its original position. A needle valve (8) in a passage between chambers (A and B) controls the rate at which the pressure difference changes. The pressure difference makes compensation for the change in the axial force of the flyweights until the engine stops its increase or decrease of rpm. If the force on the pilot valve compensating land plus the axial force of the flyweights is not the same as the force of the speeder spring, the pilot valve will move. This movement is known as hunting (movement of the pilot valve that is not the result of a change in load or desired rpm of the engine).

The governor will hunt each time the engine actually stops its increase or decrease of rpm at any other rpm than that desired. The governor will hunt more after a rapid or large change of load or desired rpm than after a gradual or small change.

PSG GOVERNOR INSTALLED (Typical Example)
8. Needle valve.

Speed Adjustment

Speed adjustments are made by a 24V DC reversible synchronizing motor (2). The motor is controlled by a switch (1) that can be put in a remote location.

3 WIRE SYNCHRONIZING MOTOR SHOWN
1. Switch. 2. Motor.

The synchronizing motor drives clutch assembly (3). The clutch assembly protects the motor if it is run against the adjustment stops.

When the clutch assembly is turned clockwise it pushes link assembly (4) down. The force of compression in speeder spring (5) is increased. This causes pilot valve (6) to move down; see PILOT VALVE OPERATION. The engine will increase speed, then get stability at a new desired rpm.

PSG GOVERNOR
2. Synchronizing motor. 3. Clutch assembly. 4. Link assembly. 5. Speeder spring. 6. Pilot valve.

When the clutch assembly is turned counterclockwise the link assembly moves up. The force of compression in the speeder spring is decreased. This causes the pilot valve to move up. The engine will decrease speed, then get stability at a new desired rpm.

NOTE: The clutch assembly can be turned manually if necessary.

Speed Droop

Speed droop is the difference between no load rpm and full load rpm. This difference in rpm divided by the full load rpm and multiplied by 100 is the percent of speed droop.

PSG GOVERNOR
1. Pivot pin. 2. Bracket for droop adjustment screw. 3. Output shafts.

The speed droop of the PSG governor can be adjusted. The governor is isochronous when it is adjusted so that the no load and full load rpm is the same. Speed droop permits load division between two or more engines that drive generators connected in parallel or generators connected to a single shaft.

Speed droop adjustment on PSG governors is made by movement of pivot pin (1). When the pivot pin is put in alignment with the output shafts, movement of the output shaft lever will not change the force of the speeder spring. When the force of the speeder spring is kept constant, the desired rpm will be kept constant. See PILOT VALVE OPERATION. When the pivot pin is moved out of alignment with the output shafts, movement of the output shaft lever will change the force of the speeder spring proportional to the load on the engine. When the force of the speeder spring is changed, the desired rpm of the engine will change.

An adjustment lever outside the governor connected to pivot pin (1) by link (4) is used to make an adjustment of the speed droop.

LATER PSG GOVERNOR
1. Pivot pin. 4. Link.

Air Inlet And Exhaust System

The air inlet and exhaust system components are: air cleaner, turbocharger, aftercooler (if so equipped), inlet manifold (passages inside the cylinder block), cylinder head, valves and valve system components, and exhaust manifold.

AIR INLET AND EXHAUST SYSTEM
1. Exhaust manifold. 2. Inlet manifold and aftercooler. 3. Engine cylinder. 4. Air inlet. 5. Turbocharger compressor wheel. 6. Turbocharger turbine wheel. 7. Exhaust outlet.

Clean inlet air from the air cleaner is pulled through the air inlet (4) of the turbocharger by the turning compressor wheels (5). The compressor wheel causes a compression of the air. The air then goes to the aftercooler (if so equipped), and then to the inlet manifold (2) of the engine. When the intake valves open, the air goes into the engine cylinder (3) and is mixed with the fuel for combustion. When the exhaust valves open, the exhaust gases go out of the engine cylinder and into the exhaust manifold (1). From the exhaust manifold, the exhaust gases go through the blades of the turbine wheel (6). This causes the turbine wheel and compressor wheel to turn. The exhaust gases then go out the exhaust outlet (7) of the turbocharger.

AIR INLET AND EXHAUST SYSTEM
1. Exhaust manifold. 2. Aftercooler. 4. Air inlet. 7. Exhaust outlet. 8. Turbocharger.

AIR FLOW SCHEMATIC (Engines With Aftercooler)
1. Exhaust manifold. 2. Aftercooler. 4. Air inlet. 7. Exhaust outlet. 8. Turbocharger.

AIR FLOW SCHEMATIC (Engines Without Aftercooler)
1. Exhaust manifold. 2. Elbow to inlet manifold. 4. Air inlet. 7. Exhaust outlet. 8. Turbocharger.

Aftercooler

Some engines have an aftercooler (3) installed above the inlet manifold.

AIR INLET SYSTEM
1. Air inlet to turbo. 2. Compressed air from turbocharger. 3. Aftercooler. 4. Elbow on front bonnet of oil cooler.

The aftercooler lowers the temperature of the inlet air that comes from the compressor outlet of the turbocharger to approximately 93° C (200° F). This cooler air then goes into the engine cylinders.

Coolant for the aftercooler comes from the front bonnet (4) on the oil cooler.

Turbocharger

The turbocharger is installed at the rear of the engine on a cross pipe between the two exhaust manifolds. All the exhaust gases from the engine go through the turbocharger.

The exhaust gases go through the blades of turbine wheel (6). This causes the turbine wheel and compressor wheel (5) to turn, which causes a compression of the inlet air.

TURBOCHARGER (Industrial Engine)
1. Exhaust manifolds. 2. Oil drain line. 3. Oil supply line. 4. Air inlet. 7. Exhaust outlet. 20. Air outlet. 21. Turbocharger.

TURBOCHARGER (Marine Engine)
1. Exhaust manifolds (watercooled). 2. Oil drain line. 3. Oil supply line. 4. Air inlet. 7. Exhaust outlet. 21. Turbocharger (water cooled). 22. Water outlet lines. 23. Water inlet line (from rear oil cooler bonnet).

When the load on the engine is increased, more fuel is put into the engine. This makes more exhaust gases and will cause the turbine and compressor wheels of the turbocharger to turn faster. As the turbocharger turns faster, it gives more inlet air and makes it possible for the engine to burn more fuel and will give the engine more power.

Maximum rpm of the turbocharger is controlled by the rack setting, the high idle speed setting and the height above sea level at which the engine is operated.

TURBOCHARGER (Typical Example)
4. Air inlet. 5. Compressor wheel. 6. Turbine wheel. 7. Exhaust outlet. 8. Compressor housing. 9. Thrust bearing. 10. Sleeve. 11. Lubrication inlet port. 12. Turbine housing. 13. Sleeve. 14. Sleeve. 15. Oil deflector. 16. Bearing. 17. Oil outlet port. 18. Bearing. 19. Exhaust inlet. 20. Air outlet.

Bearings (16 and 18) for the turbocharger use engine oil under pressure for lubrication. The oil comes in through the oil inlet port (11) and goes through passages in the center section for lubrication of the bearings. Oil from the turbocharger goes out through the oil outlet port (17) in the bottom of the center section and goes back to the engine lubricating system.

The fuel rack adjustment is done at the factory for a specific engine application. The governor housing is sealed to prevent changes to the adjustment of the rack and the high idle speed setting.

Valves And Valve System Components

VALVE SYSTEM COMPONENTS
1. Intake bridge. 2. Intake rocker arm. 3. Push rod. 4. Rotocoil assemblies. 5. Valve spring. 6. Valve guide. 7. Intake valves. 8. Lifter. 9. Camshaft.

The valves and valve system components control the flow of inlet air and exhaust gases into and out of the cylinder during engine operation.

The intake and exhaust valves are opened and closed by movement of these components: crankshaft, camshaft, lifters, push rods, rocker arms, bridges, and valve springs. Rotation of the crankshaft causes rotation of the camshaft. The camshaft gear is timed to, and driven by, a gear on the front of the crankshaft. As camshaft (9) turns, the cams of the camshaft also turn and cause lifters (8) to go up and down. This movement makes push rods (3) move rocker arms (2). Movement of the rocker arms will make intake and exhaust bridges (1 and 11) move up and down on dowels mounted in the cylinder head.

These bridges let one rocker arm operate two valves (intake or exhaust) for each cylinder. There are two intake and two exhaust valves in each cylinder. Movement of the bridges will make the intake and exhaust valves in the cylinder head open and close according to the firing order (injection sequence) of the engine. One valve spring (5) for each valve helps to hold the valves in the closed position.

VALVE SYSTEM COMPONENTS
1. Intake bridge. 2. Intake rocker arm. 7. Intake valves. 10. Exhaust rocker arm. 11. Exhaust bridge. 12. Exhaust valves.

Rotocoil assemblies (4) cause the valves to have rotation while the engine is running. This rotation of the valves keeps the deposit of carbon on the valves to a minimum and gives the valves longer service life.

Lubrication System

Oil Flow Through The Oil Cooler And Oil Filters

With the engine warm (normal operation), oil is pulled from oil pan (6) through a bell assembly and pipe to oil pump (5). The oil pump sends oil through a pipe to a passage in the cylinder block. The oil then goes through oil cooler bypass valve (4) into oil cooler (3). The oil goes out of the oil cooler through oil filters (7). The clean oil then goes through oil filter bypass valve (2), then into the oil manifold on the right side of the cylinder block.

SCHEMATIC OF OIL FLOW
1. To oil manifold. 2. Filter bypass valve. 3. Engine oil cooler. 4. Cooler bypass valve. 5. Oil pump. 6. Oil pan. 7. Oil filters.

When the engine is cold (starting condition), bypass valves (2 and 4) open because cold oil with high viscosity causes a restriction to the oil flow through oil cooler (3) and filters (7). When the bypass valves are open, oil flows directly through passages in the valve body to the oil manifold.

When the oil gets warm, the pressure difference at the bypass valves decreases and the bypass valves close. This gives normal oil flow through oil cooler (3) and oil fitlers (7).

The bypass valves will also open when there is a restriction in the oil cooler or oil filters. This action does not let an oil cooler or oil filter with a restriction prevent the lubrication of the engine.

There is also a bypass valve in engine oil pump (5). This bypass valve controls the pressure of the oil from the oil pump. The oil pump can put more oil into the system than is needed. When there is more oil than needed, the oil pressure goes up and the bypass valve will open. This lets the oil that is not needed to go back to the inlet oil passage of the oil pump.

Oil Flow In The Engine

The oil manifolds are cast into the sides of the cylinder block. Oil goes into manifold (16) from the bypass valve body. From manifold (16) oil is sent to manifold (12) through drilled passages in the cylinder block that connect main bearing bores (17) and camshaft bearing bores (9). Oil goes through holes in the bearings and gives them lubrication. Oil from the main bearings goes through holes drilled in the crankshaft to give lubrication to the connecting rod bearings. A small amount of oil from the oil manifolds goes through tubes (10) to make the pistons cooler.

Oil goes through grooves in the outside of the front and rear camshaft bearings to passages (7 and 8). The oil in these passages gives lubrication to the valve lifters and rocker arm shafts. Holes in the rocker arm shafts let the oil give lubrication to the valve system components in the cylinder head.

The fuel injection pumps and governor get oil from passage (5) in the cylinder block. Oil for the hydraulic operation of the hydra-mechanical governor comes from a small gear pump between the injection pump housing and the governor. This small pump also supplies oil pressure for the fuel ratio control. Oil for the fuel ratio is taken from the top of the governor on later engines, and from the top of the fuel injection pump housing on earlier engines. The automatic timing advance unit gets oil from the injection pump housing through passages in the injection pump camshaft.

The bearing of the idler gear on the front of the engine gets oil through a passage in the idler gear shaft that is connected to passage (14).

The bearing for the balancer gear at the rear of the engine gets oil through a passage in the balancer gear shaft that is connected to passage (2).

Tube assembly (11) gives oil to the turbocharger impeller shaft bearings. The oil goes out of the turbocharger through tube assembly (18) to the flywheel housing.

Oil that gives pressure lubrication to gear shafts and bearings then flows free to give lubrication to the gear teeth. After the oil for lubrication has done its work it flows free back to the oil pan.

SCHEMATIC OF OIL FLOW IN THE ENGINE
1. To air compressor. 2. To rear idler gear. 3. To rocker arm shaft. 4. To power take-off. 5. To fuel injection pump housing. 6. Rocker arm shaft. 7. To rocker arm shaft and valve lifters. 8. To valve lifters. 9. Bore for camshaft bearings. 10. Tube. 11. To turbocharger. 12. Oil manifold (left side). 13. To timing gear housing. 14. To front idler gear. 15. Oil supply line to manifold in cylinder block. 16. Oil manifold (right side). 17. Main bearing bores.

LUBRICATION SYSTEM COMPONENTS
11. Oil supply line to turbocharger. 18. Oil drain line from turbocharger. 19. Bypass valve for oil cooler. 20. Bypass valve for oil filters. 21. Oil cooler. 22. Tube for oil level gauge. 23. Oil inlet to cooler. 24. Oil outlet from oil cooler (inlet to filters). 25. Oil pan. 26. Oil filters. 27. Marine gear oil cooler or engine oil cooler bypass.

Cooling System

This engine has a pressure type cooling system. A pressure type cooling system gives two advantages. The first advantage is that the cooling system can have safe operation at a temperature that is higher than the normal boiling (steam) point of water. The second advantage is that this type system prevents cavitation (the sudden making of low pressure bubbles in liquids by mechanical forces) in the water pump. With this type system, it is more difficult for an air or steam pocket to be made in the cooling system.

Radiator Cooled System

In normal operation (engine warm), water pump (10) sends coolant through engine oil cooler (7) and then into the cylinder block. Coolant moves through the cylinder block to both cylinder heads, and then goes to the housings for the temperature regulators (3). The temperature regulators are open and most of the coolant goes through the outlets (4) to radiator (5). The coolant is made cooler as it moves through the radiator. When the coolant gets to the bottom of the radiator, it goes to water pump inlet (11).

COOLING SYSTEM COMPONENTS (Industrial Engine Shown)
1. Turbocharger. 2. Aftercooler. 3. Temperature regulator housing. 4. Outlet to radiator top. 6. Outlet bonnet of oil cooler. 7. Oil cooler. 8. Line to aftercooler. 9. Inlet bonnet of oil cooler. 10. Water pump. 11. Water pump inlet, from radiator bottom. 12. Radiator bypass lines.

EXAMPLE OF RADIATOR COOLED SYSTEM
1. Turbochargers. 2. Aftercooler. 3. Temperature regulator housings. 4. Outlet from temperature regulator housing to radiator top (one on each side off the engine front). 5. Radiator. 6. Outlet bonnet of oil cooler. 7. Engine oil cooler. 8. Line to aftercooler. 9. Inlet bonnet of oil cooler. 10. Water pump. 11. Water pump inlet, from radiator bottom. 12. Radiator bypass lines.

NOTE: The water temperature regulator is an important part of the cooling system. It divides coolant flow between radiator (5) and radiator bypass lines (12) as necessary to maintain the correct temperature. If the water temperature regulator is not installed in the system, there is no mechanical control, and most of the coolant will take the path of least resistance through the bypass. This will cause the engine to overheat in hot weather. In cold weather, even the small amount of coolant that goes through the radiator is too much, and the engine will not get to normal operation temperatures.

When the engine is cold, the water temperature regulator is closed, and the coolant is stopped from going to the radiator. The coolant goes from the temperature regulator housings (3) back to the water pump (10) through radiator bypass lines (12).

On engines with an aftercooler, part of the coolant flows to the engine oil cooler and part of the coolant flows through line (8) to the aftercooler. From the aftercooler, the coolant flows through the block, through the heads and back to the regulators.

On engines without an aftercooler, line (8) becomes an oil cooler bypass line, and it will connect to outlet bonnet (6) of the oil cooler. Part of the coolant will flow through engine oil cooler (7), and part will flow through bypass line (8). From outlet bonnet (6) all the coolant will flow into the cylinder block and then to both cylinder heads.

On some engine applications, water-cooled manifolds and a water-cooled turbocharger is used. With these engines, coolant taken from the rear oil cooler bonnet (6), flows to the bottom of the watercooled turbocharger. From the top of the turbocharger, part of the coolant flows through a line back to the water pump and part of the coolant flows through the manifolds back to the regulators.

Systems Without Radiators

Keel Cooled Systems

With this cooling system an expansion tank is used, but the coolant flow in the engine is the same as the radiator cooled system. The coolant flows through the engine and back to the expansion tank in a constant cycle. When the temperature becomes high enough to open the regulators, the coolant flow is directed out through connection (7) to the keel cooling system, then back to the expansion tank through connection (3). The engine coolant is cooled as it flows through the keel circuit (9) by the sea water flowing past the cooling pipes on the keel.

COOLING SYSTEM COMPONENTS (Marine Engine With Aftercooler)
1. Turbocharger. 3. Jacket water return connection (from either keel cooler or heat exchanger). 4. Vent lines. 5. Temperature regulator housings (both sides). 7. Jacket water outlet connection (to keel cooler or heat exchanger). 8. Water pump. 12. Marine gear oil cooler or engine oil cooler bypass line. 13. Engine oil cooler. 14. Water cooled manifolds. 15. Inlet line for water-cooled turbocharger. 16. Turbocharger water outlet line to water-cooled manifolds. 17. Turbocharger water outlet line to expansion tank. 18. Expansion tank. 19. Water pump inlet line from expansion tank. 20. Line to aftercooler.

EXAMPLE OF KEEL COOLED SYSTEM
1. Water cooled turbocharger. 2. Aftercooler. 3. Inlet connection for engine water return (either side). 4. Vent lines. 5. Water temperature regulator (both sides). 6. Connection for auxiliary tank. 7. Outlet connection for engine water. 8. Engine water pump. 9. Keel cooler. 10. Duplex filter. 11. Bypass filter. 12. Oil cooler bypass or marine gear cooler. 13. Oil cooler. 14. Water cooled exhaust manifold.

Heat Exchanger Cooled System

When the engine is cooled by the heat exchanger system, an extra (auxillary) water pump (6) is used to constantly pump filtered water from another source (either sea water or storage water) through the heat exchanger. When the engine reaches a temperature high enough to open the regulators, the water flow is directed around the heat exchanger core (10) and then back to the expansion tank. The cooled water in the expansion tank is then picked up by the engine water pump (8) and directed back through the engine.

EXAMPLE OF HEAT EXCHANGER COOLED SYSTEM
1. Water cooled turbocharger. 2. Aftercooler. 3. Inlet connection for engine water return (either side). 4. Vent lines. 5. Temperature regulator (both sides). 6. Auxiliary water pump. 7. Outlet connection for engine water (either side). 8. Engine water pump. 9. Duplex filter. 10. Heat exchanger. 11. Oil cooler bypass or marine gear cooler. 12. Engine oil cooler. 13. Water cooled exhaust manifold.

Coolant Conditioner

Some conditions of operation have been found to cause pitting (small holes in the metal surface) from corrosion or cavitation erosion (wear caused by air bubbles in the coolant) on the outer surface of the cylinders liners and the inner surface of the cylinder block next to the liners. The addition of a corrosion inhibitor (a chemical that gives a reduction of pitting) can keep this type of damage to a minimum.

The "spin-on" coolant conditioner elements, similar to the fuel filter and oil filter elements, fasten to a base that is mounted on the engine or is remote mounted. Coolant flows through lines from the water pump to the base and back to the air compressor. There is a constant flow of coolant through the element.

The element has a specific amount of inhibitor for acceptable cooling system protection. As coolant flows through the element, the corrosion inhibitor, which is a dry material, dissolves (goes into solution) and mixes to the correct concentration. Two basic types of elements are used for the cooling system, and they are called the "PRECHARGE" and the "MAINTENANCE" elements. Each type of element has a specific use and must be used correctly to get the necessary concentration for cooling system protection. The elements also contain a filter and should be left in the system so coolant flows through it after the conditioner material is disolved.

The "PRECHARGE" element has more than the normal amount of inhibitor, and is used when a system is first filled with new coolant (unless Dowtherm 209 Antifreeze is used). This element has to add enough inhibitor to bring the complete cooling system up to the correct concentration.

The "MAINTENANCE" elements have a normal amount of inhibitor and are installed at the first change interval and provide enough inhibitor to keep the corrosion protection at an acceptable level. After the first change period, only "MAINTENANCE" elements are installed at specified interval to give protection to the cooling system.

Basic Block

Cylinder Block, Liners And Heads

The cylinders in the left side of the block make an angle of 65° with the cylinders in the right side of the block. The main bearing caps are fastened to the block with two bolts per cap.

The cylinder liners can be removed for replacement. The top surface of the block is the seat for the cylinder liner flange. Engine coolant flows around the liners to keep them cool. Three O-ring seals around the bottom of the liner make a seal between the liner and the block. A filler band at the top of each liner forms a seal between the liner and the cylinder block.

A steel spacer plate is used between the cylinder head and block. A thin gasket with a rubber coating is used between the plate and the block to seal water and oil. A thick gasket of metal and asbestos is used between the plate and the head to seal combustion gases, water and oil.

The engine has a single, cast head on each side. Four vertical valves (two intake and two exhaust), controlled by a pushrod valve system, are used per each cylinder. The opening for the direct injection adapter or prechamber is located between the four valves. Series ports (passages) are used for both intake and exhaust valves.

The size of the pushrod openings through the head permits the removal of the valve lifters with the head installed.

Valve guides without shoulders are pressed into the cylinder head.

Pistons, Rings And Connecting Rods

The aluminum pistons have three rings; two compression rings and one oil ring. All rings are located above the piston pin bore. The two compression rings are of the KEYSTONE type, which have a tapered shape. The seat for the rings is an iron band that is cast into the piston. The action of the rings in the piston groove, which is also tapered, helps prevent seizure of the rings caused by too much carbon deposit. The oil ring is a standard (conventional) type. Oil returns to the crankcase through holes in the oil ring groove.

The piston for the direct injection engine has a cardioid design (special shape) on the top surface to help combustion efficiency. The piston pin is held in place by two snap rings that fit in grooves in the pin bore of the piston.

The piston for precombustion engines has a steel heat plug fastened to the top of the piston at the center.

The connecting rod has a taper on the pin bore end. This gives the rod and piston more strength in the areas with the most load.

Oil spray tubes, located on the cylinder block main webs, direct oil to cool and give lubrication to the piston components and cylinder walls.

Crankshaft

The crankshaft changes the combustion forces in the cylinder into usable rotating torque which powers the machine. Vibration, caused by combustion impacts along the crankshaft, is kept small by a vibration damper on the front of the crankshaft.

There is a gear at the front of the crankshaft to drive the timing gears and the oil pump. Lip seals and wear sleeves are used at both ends of the crankshaft for easy replacement and a reduction of maintenance cost. Pressure oil is supplied to all bearing surfaces through drilled holes in the crankshaft. The crankshaft is supported by five main bearings. A thrust plate at either side of the center main bearing controls the end play of the crankshaft.

Camshaft

The engine has a single camshaft that is driven at the front end. Five bearings support the camshaft. As the camshaft turns, each cam (lobe) (through the action of valve systems components) moves either two exhaust valves or two intake valves for each cylinder. The camshaft gear must be timed to the crankshaft gear. The relation of the cams (lobes) to the camshaft gear cause the valves in each cylinder to open and close at the correct time.

A gear on the rear of the camshaft is used to drive the balancer gear. Vibration, caused by the balance of the crankshaft, is kept small by the balancer gear.

Vibration Damper

The twisting of the crankshaft, due to the regular power impacts along its length, is called twisting (torsional) vibration. The fluid type vibration damper is installed on the front end of the crankshaft. It is used for reduction of torsional vibrations and stops the vibration from building up to amounts that cause damage.

Electrical System

The electrical system has three separate circuits: the charging circuit, the starting circuit and the low amperage circuit. Some of the electrical system components are used in more than one circuit. The battery (batteries), circuit breaker, ammeter, cables and wires from the battery are all common in each of the circuits.

The charging circuit is in operation when the engine is running. An alternator makes electricity for the charging circuit. A voltage regulator in the circuit controls the electrical output to keep the battery at full charge.

If the machine has a disconnect switch, the starting circuit can operate only after the disconnect switch is put in the ON position.

The starting circuit is in operation only when the start switch is activated.

On precombustion engines, the starting circuit has a glow plug for each cylinder of the diesel engine. Glow plugs are small heating units in the precombustion chambers. Glow plugs make ignition of the fuel easier when the engine is started in cold temperature.

The low amperage circuit and the charging circuit are both connected to the same side of the ammeter. The starting circuit connects to the opposite side of the ammeter.

Charging System Components

Alternator (Delco-Remy)

The alternator is driven by V-type belts from the crankshaft pulley. This alternator is a three phase, self-rectifying charging unit, and the regulator is part of the alternator.

This alternator design has no need for slip rings or brushes, and the only part that has movement is the rotor assembly. All conductors that carry current are stationary. The conductors are: the field winding, stator windings, six rectifying diodes and the regulator circuit components.

The rotor assembly has many magnetic poles like fingers with air space between each opposite pole. The poles have residual magnetism (like permanent magnets) that produce a small amount of magnet-like lines of force (magnetic field) between the poles. As the rotor assembly begins to turn between the field winding and the stator windings, a small amount of alternating current (AC) is produced in the stator windings from the small magnetic lines of force made by the residual magnetism of the poles. This AC current is changed to direct current (DC) when it passes through the diodes of the rectifier bridge. Most of this current goes to charge the battery and to supply the low amperage circuit, and the remainder is sent on to the field windings. The DC current flow through the field windings (wires around an iron core) now increases the strength of the magnetic lines of force. These stronger lines of force now increase the amount of AC current produced in the stator windings. The increased speed of the rotor assembly also increases the current and voltage output of the alternator.

The voltage regulator is a solid state (transistor, stationary parts) electronic switch. It feels the voltage in the system and switches on and off many times a second to control the field current (DC current to the field windings) for the alternator to make the needed voltage output.

DELCO-REMY ALTERNATOR
1. Regulator. 2. Roller bearing. 3. Stator winding. 4. Ball bearing. 5. Rectifier bridge. 6. Field winding. 7. Rotor assembly. 8. Fan.

Alternator (Bosch)

The alternator is driven by two V-type belts from the fan pulley. It is a 28 volt, 17 ampere unit with a capacitor which has no moving parts installed on the end opposite the pulley. The alternator is made up of a cover assembly on the drive end, rotor assembly, stator assembly, rectifier and heat removal assemblies, brush and holder assembly, cover assembly on the ring end, and capacitor assembly.

The rotor assembly has the field windings (wires around an iron core) which make magnet like lines of force when direct current (DC) flows through them. As the rotor turns, the magnet like lines of force are broken by the stator. This makes an alternating current (AC) in the stator. The rectifier has diodes which change the alternating current (AC) from the stator to direct current (DC). Most of the direct current (DC) goes to charge the battery and make a supply of direct current (DC) for the low amperage circuit. The remainder of the direct current (DC) is sent to the field windings through the brushes.

ALTERNATOR
1. Cover assembly. 2. Rectifier and heat removal assemblies. 3. Rotor assembly. 4. Stator assembly. 5. Cover assembly. 6. Fan. 7. Location to connect capacitor. 8. Brush and holder assembly. 9. Slip rings.

Alternator (Prestolite)

The alternator is driven by two V-type belts from the fan pulley. It is a 24 volt, 19 ampere unit with a regulator which has no moving parts (solid state) installed on the side opposite the pulley. The alternator is made up of a head assembly on the drive end, rotor assembly, stator assembly, rectifier and heat removal assemblies, brush and holder assembly, head assembly on the ring end and regulator.

The rotor assembly has the field windings (wires around an iron core) which make magnet like lines of force when direct current (DC) flows through them. As the rotor turns, the magnet like lines of force are broken by the stator. This makes an alternating current (AC) in the stator. The rectifier has diodes which change the alternating current (AC) from the stator to direct current (DC). Most of the direct current (DC) goes to charge the battery and make a supply of direct current (DC) for the low amperage circuit. The remainder of the direct current (DC) is sent to the field windings through the brushes.

PRESTOLITE ALTERNATOR
1. Brush assembly. 2. Stator. 3. Rotor. 4. Roller bearing. 5. Slip rings. 6. Ball bearing.

Alternator (Motorola)

The alternator is a three phase, self-rectifying charging unit that is driven by V-type belts. The only part of the alternator that has movement is the rotor assembly. Rotor assembly (4) is held in position by a ball bearing at each end of the rotor shaft.

The alternator is made up of a front frame at the drive end, rotor assembly (4), stator assembly (3), rectifier assembly, brushes and holder assembly (5), slip rings (1) and rear end frame. Fan (2) provides heat removal by the movement of air thru the alternator.

Rotor assembly (4) has field windings (wires around an iron core) that make magnetic lines of force when direct current (DC) flows thru them. As the rotor assembly turns, the magnetic lines of force are broken by stator assembly (3). This makes alternating current (AC) in the stator. The rectifier assembly diodes that change the alternating current (AC) from the stator to direct current (DC). Most of the DC current goes to charge the battery and make a supply for the low amperage circuit. The remainder of the DC current is sent to the field windings thru the brushes.

MOTOROLA ALTERNATOR
1. Slip rings. 2. Fan. 3. Stator assembly. 4. Rotor assembly. 5. Brush and holder assembly.

Alternator (Nippondenso)

The alternator is driven by a V-type belt from the crankshaft pulley. It is a 12 volt, 40 ampere unit with a regulator which has no moving parts (solid state). The only part in the alternator which has movement is rotor assembly (9). Rotor assembly (9) is held in position by a ball bearing at each end of rotor shaft (8).

The alternator is made up of a frame (3) on the drive end, rotor assembly (9), stator assembly (5), rectifier assembly (11), brushes (7) and holder assembly, slip rings (13), rear end frame (12) and regulator (6). Drive pulley (1) has a fan (2) for heat removal by the movement of air thru the alternator.

ALTERNATOR SCHEMATIC (WITH REGULATOR ATTACHED)
1. Pulley. 2. Fan. 3. Drive end frame. 4. Stator coils. 5. Stator assembly. 6. Regulator. 7. Brushes. 8. Rotor shaft. 9. Rotor assembly. 10. Field windings. 11. Rectifier assembly. 12. Rear end frame. 13. Slip rings.

Rotor assembly (9) has field windings (10) (wires around an iron core) which make magnetic lines of force when direct current (DC) flows through them. As the rotor turns, the magnetic lines of force are broken by stator assembly (5). This makes an alternating current (AC) in the stator. Rectifier assembly (11) has diodes which change the alternating current (AC) from the stator to direct current (DC). Most of the direct current (DC) goes to charge the battery and make a supply of direct current (DC) for the low amperage circuit. The remainder of the direct current (DC) is sent to field windings (10) through brushes (7).

Alternator Regulator (Bosch)

The voltage regulator is an electronic switch. It feels the voltage in the system and gives the necessary field current (current to the field windings of the alternator) for the alternator to make the needed voltage. The voltage regulator controls the field current to the alternator by switching on and off many times a second.

ALTERNATOR REGULATOR

Alternator Regulator (Prestolite)

The voltage regulator is a solid state (transistor, no moving parts) electronic switch. It feels the voltage in the system and gives the necessary field current (current to the field windings of the alternator) for the alternator to make the needed voltage. The voltage regulator controls the field current to the alternator by switching on and off many times a second.

Alternator Regulators (Nippondenso)

The regulator is fastened to the alternator by two different methods. One method fastens the regulator to the top, rear of alternator. With the other method the regulator is fastened separately by use of a wire and a connector that goes into the alternator.

The voltage regulator is a solid state (transistor, no moving parts) electronic switch. It feels the voltage in the system and gives the necessary field current (current to the field windings of the alternator) for the alternator to make the needed voltage. The voltage regulator controls the field current to the alternator by switching on and off many times a second. There is no voltage adjustment for this regulator.

Alternator Regulator (Motorola)

The voltage regulator is not fastened to the alternator, but is mounted separately and is connected to the alternator with wires. The regulator is a solid state (transistor, stationary parts) electronic switch. It feels the voltage in the system and switches on and off many times a second to control the field current (DC current to the field windings) for the alternator to make the needed voltage output. There is a voltage adjustment for this regulator to change the alternator output.

Starting System Components

Solenoid

A solenoid is a magnetic switch that does two basic operations:

a. Closes the high current starter motor circuit with a low current start switch circuit.

b. Engages the starter motor pinion with the ring gear.

TYPICAL SOLENOID SCHEMATIC

The solenoid switch is made of an electromagnet (one or two sets of windings) around a hollow cylinder. There is a plunger (core) with a spring load inside the cylinder that can move forward and backward. When the start switch is closed and electricity is sent thru the windings, a magnetic field is made that pulls the plunger forward in the cylinder. This moves the shift lever (connected to the rear of the plunger) to engage the pinion drive gear with the ring gear. The front end of the plunger then makes contact across the battery and motor terminals of the solenoid, and the starter motor begins to turn the flywheel of the engine.

When the start switch is opened, current no longer flows thru the windings. The spring now pushes the plunger back to the original position, and, at the same time, moves the pinion gear away from the flywheel.

When two sets of windings in the solenoid are used, they are called the hold-in winding and the pull-in winding. Both have the same number of turns around the cylinder, but the pull-in winding uses a larger diameter wire to produce a greater magnetic field. When the start switch is closed, part of the current flows from the battery thru the hold-in windings, and the rest flows thru the pull-in windings to motor terminal, then thru the motor to ground. When the solenoid is fully activated (connection across battery and motor terminal is complete), current is shut off thru the pull-in windings. Now only the smaller hold-in windings are in operation for the extended period of time it takes to start the engine. The solenoid will now take less current from the battery, and heat made by the solenoid will be kept at an acceptable level.

Starter Motor

The starter motor is used to turn the engine flywheel fast enough to get the engine to start running.

The starter motor has a solenoid. When the start switch is activated, the solenoid will move the starter pinion to engage it with the ring gear on the flywheel of the engine. The starter pinion will engage with the ring gear before the electric contacts in the solenoid close the circuit between the battery and the starter motor. When the circuit between the battery and the starter motor is complete, the pinion will turn the engine flywheel. A clutch gives protection for the starter motor so that the engine can not turn the starter motor too fast. When the start switch is released, the starter pinion will move away from the ring gear.

STARTER MOTOR CROSS SECTION
1. Field. 2. Solenoid. 3. Clutch. 4. Pinion. 5. Commutator. 6. Brush assembly. 7. Armature.

Magnetic Switch

A magnetic switch (relay) is used sometimes for the starter solenoid or glow plug circuit. Its operation electrically, is the same as the solenoid. Its function is to reduce the low current load on the start switch and control low current to the starter solenoid or high current to the glow plugs.

Other Components

Circuit Breaker

CIRCUIT BREAKER SCHEMATIC
1. Reset button. 2. Disc in open position. 3. Contacts. 4. Disc. 5. Battery circuit terminals.

The circuit breaker is a switch that opens the battery circuit if the current in the electrical system goes higher than the rating of the circuit breaker.

A heat activated metal disc with a contact point makes complete the electric current through the circuit breaker. If the current in the electrical system gets too high, it causes the metal disc to get hot. This heat causes a distortion of the metal disc which opens the contacts and breaks the circuit. A circuit breaker that is open can be reset (an adjustment to make the circuit complete again) after it becomes cool. Push the reset button to close the contacts and reset the circuit breaker.

Shutoff Solenoid

The rack shutoff solenoid, when activated, moves the shutoff lever in the governor housing which in turn moves the fuel rack to the fuel closed position. The solenoid is activated by a manual control switch.

Wiring Diagrams

Many types of electrical systems are available for these engines. Some charging systems use an alternator and a regulator in the wiring circuit. Others have the regulator inside the alternator. Some starting systems have one starter motor and others have two starter motors.

On precombustion engines, glow plugs are provided for low temperature starting conditions. Systems without glow plugs are usually used where ideal starting conditions exist or where an Automatic Start-Stop system is used.

A fuel pressure switch is used in all systems with an external regulator. The switch prevents current discharge (field excitation) to alternator from the battery when the engine is not in operation. In systems where the regulator is part of the alternator, the transistor circuit prevents current discharge to the alternator and the fuel pressure switch is not required.

All wiring schematics are usable with 12, 24, 30 or 32 volts unless the title gives a specific description.

NOTE: Automatic Start-Stop systems use different wiring diagrams. Make reference to the ATTACHMENTS section of this Service Manual.

The chart that follows gives the correct wire sizes and color codes.

Insulated Electrical Systems (Regulator Separate From Alternator)

CHARGING SYSTEM
1. Ammeter. 2. Regulator. 3. Battery. 4. Pressure switch. 5. Alternator.

CHARGING SYSTEM WITH GLOW PLUGS
1. Heat-Start switch. 2. Magnetic switch. 3. Glow plugs. 4. Ammeter. 5. Regulator. 6. Battery. 7. Pressure switch. 8. Alternator.

CHARGING SYSTEM WITH ELECTRIC STARTING MOTOR
1. Start switch. 2. Ammeter. 3. Regulator. 4. Starting motor. 5. Battery. 6. Pressure switch. 7. Alternator.

CHARGING SYSTEM WITH ELECTRIC STARTING MOTOR AND GLOW PLUGS
1. Magnetic switch. 2. Heat-Start switch. 3. Ammeter. 4. Glow plugs. 5. Regulator. 6. Battery. 7. Starting motor. 8. Pressure switch. 9. Alternator.

CHARGING SYSTEM WITH TWO ELECTRIC STARTING MOTORS
1. Magnetic switch. 2. Start switch. 3. Ammeter. 4. Regulator. 5. Battery. 6. Starting motor. 7. Pressure switch. 8. Alternator.

CHARGING SYSTEM WITH TWO ELECTRIC STARTING MOTORS AND GLOW PLUGS
1. Heat-Start switch. 2. Magnetic switch. 3. Glow plugs. 4. Ammeter. 5. Regulator. 6. Battery. 7. Starting motor. 8. Pressure switch. 9. Alternator.

CHARGING SYSTEM
1. Ammeter. 2. Alternator. 3. Battery.

CHARGING SYSTEM WITH GLOW PLUGS
1. Heat-Start switch. 2. Magnetic switch. 3. Glow plugs. 4. Ammeter. 5. Battery. 6. Alternator.

CHARGING SYSTEM WITH ELECTRIC STARTING MOTOR
1. Start switch. 2. Ammeter. 3. Alternator. 4. Battery. 5. Starting motor.

CHARGING SYSTEM WITH ELECTRIC STARTING MOTOR AND GLOW PLUGS
1. Heat-Start switch. 2. Magnetic switch. 3. Glow plugs. 4. Ammeter. 5. Battery. 6. Starting motor. 7. Alternator.

CHARGING SYSTEM WITH TWO ELECTRIC STARTING MOTORS
1. Magnetic switch. 2. Start switch. 3. Ammeter. 4. Battery. 5. Starting motors. 6. Alternator.

CHARGING SYSTEM WITH TWO ELECTRIC STARTING MOTORS AND GLOW PLUGS
1. Heat-Start switch. 2. Magnetic switch. 3. Glow plugs. 4. Ammeter. 5. Battery. 6. Starting motors. 7. Alternator.

Grounded Electrical Systems (Regulator Separate From Alternator)

CHARGING SYSTEM
1. Ammeter. 2. Regulator. 3. Battery. 4. Pressure switch. 5. Alternator.

CHARGING SYSTEM WITH GLOW PLUGS
1. Heat-Start switch. 2. Ammeter. 3. Glow plugs. 4. Regulator. 5. Battery. 6. Pressure switch. 7. Alternator.

CHARGING SYSTEM WITH ELECTRIC STARTING MOTOR
1. Start switch. 2. Ammeter. 3. Regulator. 4. Starting motor. 5. Battery. 6. Pressure switch. 7. Alternator.

CHARGING SYSTEM WITH ELECTRIC STARTING MOTOR AND GLOW PLUGS
1. Heat-Start switch. 2. Ammeter. 3. Glow plugs. 4. Regulator. 5. Battery. 6. Starting motor. 7. Pressure switch. 8. Alternator.

CHARGING SYSTEM WITH TWO ELECTRIC STARTING MOTORS
1. Magnetic switch. 2. Start switch. 3. Ammeter. 4. Regulator. 5. Battery. 6. Starting motor. 7. Pressure switch. 8. Alternator.

CHARGING SYSTEM WITH TWO ELECTRIC STARTING MOTORS AND GLOW PLUGS
1. Heat-Start switch. 2. Magnetic switch. 3. Glow plugs. 4. Ammeter. 5. Regulator. 6. Battery. 7. Starting motor. 8. Pressure switch. 9. Alternator.

CHARGING SYSTEM
1. Ammeter. 2. Alternator. 3. Battery.

CHARGING SYSTEM WITH GLOW PLUGS
1. Heat-Start switch. 2. Ammeter. 3. Glow plugs. 4. Battery. 5. Alternator.

CHARGING SYSTEM WITH ELECTRIC STARTING MOTOR
1. Start switch. 2. Ammeter. 3. Alternator. 4. Battery. 5. Starting motor.

CHARGING SYSTEM WITH ELECTRIC STARTING MOTOR AND GLOW PLUGS
1. Heat-Start switch. 2. Ammeter. 3. Glow plugs. 4. Battery. 5. Starting motor. 6. Alternator.

CHARGING SYSTEM WITH TWO ELECTRIC STARTING MOTORS
1. Magnetic switch. 2. Start switch. 3. Ammeter. 4. Battery. 5. Starting motors. 6. Alternator.

CHARGING SYSTEM WITH TWO ELECTRIC STARTING MOTORS AND GLOW PLUGS
1. Magnetic switch. 2. Heat-Start switch. 3. Ammeter. 4. Glow plugs. 5. Battery. 6. Starting motors. 7. Alternator.

Air Starting System

The air starting motor is used to turn the engine flywheel fast enough to get the engine running.

AIR STARTING SYSTEM (L.H. SHOWN)
1. Lubricator. 2. Relay valve. 3. Line. 4. Tee. 5. Starter control valve. 6. Hose. 7. Starting motor. 8. Deflector. 9. Line. 10. Drive housing. 11. Line.

The air starting motor can be mounted on either side of the engine. Air is normally contained in a storage tank and the volume of the tank will determine the length of time the engine flywheel can be turned. The storage tank must hold this volume of air at 1720 kPa (250 psi) when filled.

For engines which do not have heavy loads when starting, the regulator setting is approximately 690 kPa (100 psi). This setting gives a good relationship between cranking speeds fast enough for easy starting and the length of time the air starting motor can turn the engine flywheel before the air supply is gone.

If the engine has a heavy load which can not be disconnected during starting, the setting of the air pressure regulating valve needs to be higher in order to get high enough speed for easy starting.

The air consumption is directly related to speed; the air pressure is related to the effort necessary to turn the engine flywheel. The setting of the air pressure regulator can be up to 1030 kPa (150 psi), if necessary, to get the correct cranking speed for a heavily loaded engine. With the correct setting, the air starting motor can turn the heavily loaded engine as fast and as long as it can turn a lightly loaded engine.

Other air supplies can be used if they have the correct pressure and volume. For good life of the air starting motor, the supply should be free of dirt and water. A lubricator with SAE 10 nondetergent oil [for temperatures above 0°C (32°F)], or diesel fuel [for temperatures below 0°C (32°F)] should be used with the starting system. The maximum pressure for use in the air starting motor is 1030 kPa (150 psi). Higher pressures can cause problems.

AIR STARTING MOTOR (6N4147 SHOWN)
12. Vanes. 13. Rotor. 14. Pinion. 15. Gears. 16. Piston. 17. Spring.

Air for the starting motor comes from a separate air compressor system and is sent through a pressure regulator. From the pressure regulator, air goes through hose (6) to tee (4). The flow of air is then stopped by relay valve (2) until starter control valve (5) is activated. The starter control valve (5) is connected to the air supply line before relay valve (2) by line (3). When starter control valve (5) is activated, air is sent from the starter control valve through line (11) to drive housing (10) then to piston (16) for pinion (14). The air pressure on piston (16) puts spring (17) in compression and puts pinion (14) in engagement with the flywheel gear. When the pinion is in engagement, air then goes from drive housing (10), through line (9) to relay valve (2). This air activates relay valve (2) and lets the main air supply from tee (4) go through lubricator (1) and into starting motor (7).

The air with lubrication oil goes into the air motor. The pressure of the air pushes against vanes (12) in rotor (13). This turns the rotor which is connected by gears (15) to starter pinion (14) which turns the engine flywheel. The air then goes out of the starting motor through deflector (8) or an air silencer.

FLOW OF AIR THROUGH STARTING MOTOR (Seen from the pinion end of the motor) (Typical Example)

When the engine starts running the flywheel will start to turn faster than starter pinion (14). The pinion (14) retracts under this condition. This prevents damage to the motor, pinion (14) or flywheel gear.

When starter control valve (5) is released, the air pressure and flow to piston (16) behind starter pinion (14) is stopped, piston spring (17) retracts pinion (14). The relay valve (2) stops the flow of air to the air starting motor.