3406 INDUSTRIAL & MARINE ENGINES Caterpillar


Systems Operation

Usage:

Introduction

The specifications given in this book are on the basis of information available at the time the book was written. These specifications give the torques, operating pressure, measurements of new parts, adjustments and other items that will affect the service of the product.

When the words "use again" are in the description, the specification given can be used to determine if a part can be used again. If the part is equal to or within the specification given, use the part again.

When the word "permissible" is in the description, the specification given is the "maximum or minimum" tolerance permitted before adjustment, repair and/or new parts are needed.

A comparison can be made between the measurements of a worn part, and the specifications of a new part to find the amount of wear. A part that is worn can be safe to use if an estimate of the remainder of its service life is good. If a short service life is expected, replace the part.

NOTE: The specifications given for "use again" and "permissible" are intended for guidance only and Caterpillar Tractor Co. hereby expressly denies and excludes any representation, warranty or implied warranty of the reuse of any component.

NOTE: This engine uses bolts (3/8 inch size only) with washer heads in some locations. The washer head bolt does not need a plain washer, lockwasher or lockplate. Where these bolts are used on aluminum covers or housings, a plain washer is needed. If you are not sure a washer is used under a bolt head, use the Parts Book to see if a washer is needed.

Engine Design


CYLINDER AND VALVE LOCATION

Bore ... 5.40 in.(137.2 mm)

Stroke ... 6.50 in.(165.1 mm)

Number and Arrangement of Cylinders ... 6, In Line

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

No. 1 Cylinder Location ... Front

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

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

Fuel System


FUEL SYSTEM
1. Injection valve. 2. Anti-siphon block. 3. Injection pump housing. 4. Priming pump. 5. Plug. 6. Secondary filter. 7. Fuel line. 8. Return line to tank. 9. Fuel tank. 10. Primary filter. 11. Transfer pump.

This engine has a pressure type fuel system. There is a single injection pump and injection valve (1) for each cylinder. The injection pumps are in the pump housing (3) on the left side of the engine. The injection valves are in the precombustion chambers, under the valve cover.

The transfer pump (11) pulls fuel from the fuel tank (9) through the primary filter (10) and sends it through the base of the priming pump (4) and the secondary filter (6), through the anti-siphon block (2) and to the manifold of the injection pump housing. When priming pump (4) is not used, the position of fuel line (7) and plug (5) are reversed. The fuel in the manifold of the injection pump housing goes to the injection pumps. The injection pumps are in time with the engine and send fuel to the injection valves under high pressure.

Some of the fuel in the manifold is constantly sent back through the anti-siphon block (2) and through the return line (8) to the fuel tank to remove air from the system. Orifices in the anti-siphon block control the amount of fuel that goes back to the fuel tank.

The priming pump (4) is used to remove air from the fuel filter, fuel lines and components.

The transfer pump has a bypass valve and a check valve. The bypass valve (lower side) gives control to the pressure of the fuel. The extra fuel goes to the inlet of the pump.

Fuel Injection Pump Operation

Injection pump plungers (4) and lifters (8) are lifted by cams on camshaft (9) and always make a full stroke. The force of springs (5) hold the lifters (8) against the cams of the camshaft.

Fuel from fuel manifold (1) goes through inlet passage (2) in the barrel and then into the chamber above plunger (4). During injection, the camshaft cam moves plunger (4) up in the barrel. This movement will close inlet passage (2) and push the fuel out through the fuel lines to the injection valves.

The amount of fuel sent to the injection valves is controlled by turning plunger (4) in the barrel. When the governor moves fuel rack (7), the fuel rack moves gear (6) that is fastened to the bottom of plunger (4).


CROSS SECTION OF THE HOUSING FOR THE FUEL INJECTION PUMPS
1. Fuel manifold. 2. Inlet passage in pump barrel. 3. Check valve. 4. Pump plunger. 5. Spring. 6. Gear. 7. Fuel rack. 8. Lifter. 9. Camshaft.

Fuel Injection Valve

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 the correct fuel characteristic (spray pattern) for good combustion in the cylinders.

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.

Hydra-Mechanical Governor

The accelerator pedal, or governor control, is connected to the control lever on the engine governor. The governor controls the amount of fuel needed to keep the desired engine rpm.

The governor is driven by the engine and has governor weights (12), governor spring (5), valve (14) and piston (15). The valve and piston are connected to fuel rack (18). The pressure oil for the governor comes from the engine oil pump. Pressure oil goes through passage (17) and around sleeve (16). The accelerator pedal, or governor control, controls only the compression of governor spring (5). Compression of the spring always pushes to give more fuel to the engine. The centrifugal force (rotation) of governor weights (12) is always pulling 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).


HYDRA-MECHANICAL GOVERNOR (Typical Example Shown at Full Load Condition)
1. Collar. 2. Speed limiter plunger. 3. Lever assembly. 4. Seat. 5. Governor spring. 6. Thrust bearing. 7. Oil passage. 8. Drive gear (weight assembly). 9. Cylinder. 10. Bolt. 11. Spring seat. 12. Governor weights. 13. Spring. 14. Valve. 15. Piston. 16. Sleeve. 17. Oil passage. 18. Fuel rack.

Governor valve (14) is shown in the position when the force of the governor weights and the force of the governor spring are in balance.

When there is an increase in engine load, there will be a decrease in engine rpm and the rotation of governor weights (12) will get slower. (The governor weights will move toward each other.) Governor spring (5) moves valve (14) forward (toward the right in picture shown). When valve (14) moves forward, an oil passage around valve (14) opens to pressure oil. Oil now flows through passage (7) and fills the chamber behind piston (15) (the rear end of the valve stops oil flow through the rear of the cylinder, around the valve). This pressure oil pushes the piston and rack forward to give more fuel to the engine. Engine rpm goes up 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 engine load, there will be an increase in engine rpm and the rotation of governor weights (12) will get faster. This will move valve (14) backwards (toward the left in picture shown). This movement stops oil flow from the forward passage through piston (15) and allows the oil behind the piston to go out through a passage at the rear of the piston, around valve (14). Now, the pressure oil between sleeve (16) and piston (15) pushes the piston and fuel rack backwards. There is now a reduction in the amount of fuel to the engine. Engine rpm goes down 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).

When engine rpm is at LOW IDLE, a spring-loaded plunger in lever assembly (3) comes in contact with a shoulder on the adjustment screw for low idle. To stop the engine, pull back on the governor control. This will let the spring-loaded plunger move over the shoulder on the low idle adjusting screw and move the fuel rack to the fuel closed position. With no fuel to the engine cylinders, the engine will stop.

After the engine has stopped, spring (13) moves valve (14) and piston (15) to the full load position. This moves the rack to full travel position and gives full fuel flow through the fuel injection pump when starting the engine.

Oil from the engine gives lubrication to the governor weight bearing. The other parts of the governor get lubrication from "splash-lubrication" (oil thrown by other parts). Oil from the governor runs back into the housing for the fuel injection pumps.

In earlier engines, when the governor control is moved to fuel-on position to start the engine, plunger (2) of the speed limiter puts a restriction on the movement of lever assembly (3). After oil pressure of the engine gets to a safe level, plunger (2) of the speed limiter moves back (out of the way) and the governor control can be moved to increase engine rpm. Later engines do not have a speed limiter.

A small force from spring (13) moves fuel rack (18) to give a little more fuel for engine start. With the engine running, the rotation of governor weights (12) will put spring (13) in compression and cause fuel rack (18) to move back. (Spring (13) is extended only when the engine is stopped or at start.) When the engine is running, spring (13) is in compression.

Dashpot Governor

Hydra-mechanical governors for electric sets and some special applications have a piston (4) and spring (8) around bolt (2), plus an oil reservoir (10) and two adjustment screws (11 and 12). 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), lower spring seat (6) moves with more precision and the governor gives better control of the engine speed. These governors are called dashpot governors. Except for their dashpot (cushion) effect, they work the same as the standard hydra-mechanical governors.


CROSS SECTION OF DASHPOT GOVERNOR
1. Cover for idle adjustment screws. 2. Collar bolt. 3. Dashpot chamber. 4. Dashpot piston. 5. Governor control shaft. 6. Lower spring seat. 7. Governor shutoff shaft. 8. Dashpot spring. 9. Governor spring.


TOP VIEW OF DASHPOT GOVERNOR
1. Cover for idle adjustment screws. 2. Collar bolt. 5. Governor control shaft. 7. Governor shutoff shaft. 10. Dashpot reservoir. 11. Adjustment screw for dashpot. 12. Adjustment screw for supply oil to reservoir.

The oil for the dashpot action comes from the engine lubrication system. Adjustment screw (12) controls the oil flow from the lubrication system into reservoir (10), which has an overflow outlet back to the mechanical area of the governor. 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 (10). Now the governor will hunt (increase and decrease engine speed constantly) as air gets into dashpot chamber (3) and lets piston (4) and lower spring seat (6) move faster.

Dashpot adjustment screw (11) causes a restriction to oil flow into and out of dashpot chamber (3). Too much oil flow lets lower spring seat (6) move faster, and the governor will hunt. Too little oil flow will cause slow governor action.

Hydraulic Air-Fuel Ratio Control

The hydraulic air-fuel ratio control automatically controls the amount of travel of the rack in the fuel on direction until the air pressure in the inlet manifold is high enough to give complete combustion.


AIR-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.


AIR-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.


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

Automatic Timing Advance Unit

The automatic timing advance unit is installed on the front of the drive shaft (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 drive shaft for the fuel injection pump through a system of weights (2), springs (3), slides (4) and a flange (1). Two slides that are fastened to the flange fit into notches made on an angle in the weights. As centrifugal force (rotation) moves the weights outward against spring pressure, the movement of the notches in the weights causes the slides to make the flange turn through a small angle in relation to the gear. Since the flange is connected to the drive shaft for the fuel injection pump, the fuel injection timing is also changed. The automatic timing advance unit on earlier engines is held in place on the drive shaft (6) by one bolt. The automatic timing advance unit on later engines is held in place on the drive shaft (6) by four bolts.


AUTOMATIC TIMING ADVANCE UNIT (Earlier Engines)
1. Flange. 2. Weight. 3. Springs. 4. Slide. 5. Drive gear. 6. Drive shaft.

Different units are used for the "DI" engine and the "PC" engine. The "DI" unit advances the timing 21/4° between approximately low idle and 1100 rpm. The "PC" unit advances the timing 4° between approximately low idle and 1100 rpm. No adjustment can be made to these automatic timing advance units.


AUTOMATIC TIMING ADVANCE UNIT (Later Engines)
1. Flange. 2. Weight. 3. Springs. 4. Slide. 5. Drive gear. 6. Drive shaft.

Air Inlet And Exhaust System


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

The air inlet and exhaust system components are: air cleaner, inlet manifold, cylinder head, valves and valve system components, exhaust manifold, and turbocharger.

Clean inlet air from the air cleaner is pulled through the air inlet (6) of the turbocharger by the turning compressor wheel (4). The compressor wheel causes a compression of the air. The air then goes 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 (5). 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. 8. Aftercooler. 9. Turbocharger.

Aftercooler

Some engines have an aftercooler (1) installed in place of the inlet manifold.


AIR INLET SYSTEM
1. Aftercooler.

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

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

Turbocharger

The turbocharger (3) is installed on the center section or at the rear of the exhaust manifold (2). 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 into inlet manifold (1).


TURBOCHARGER
1. Inlet manifold. 2. Exhaust manifold. 3. Turbocharger.

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.


NOTICE

If the high idle rpm or the rack setting is higher than given in the RACK SETTING INFORMATION (for the height above sea level at which the engine is operated), there can be damage to engine or turbocharger parts.



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 lubrication system.

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

Valves And Valve System Components

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


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

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 holds 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


LUBRICATION SYSTEM COMPONENTS
1. Oil return line from turbocharger. 2. Oil supply line to turbocharger. 3. Oil manifold in cylinder block. 4. Oil cooler. 5. Oil filter. 6. Oil pan.

The lubrication system has the following components: oil pan, oil pump, oil cooler, oil filter, oil lines to and from the turbocharger and oil passages in the cylinder block.

Oil Flow Through The Oil Filter And Oil Cooler

With the engine warm (normal operation), oil comes from the oil pan (6) through the suction bell (9) to the oil pump (7). The oil pump sends warm oil to the oil cooler (10) and then to the oil filter (4). From the oil filter, oil is sent to the oil manifold (1) in the cylinder block and to the oil supply line (2) for the turbocharger. Oil from the turbocharger goes back through the oil return line (3) to the oil pan.

With the engine cold (starting conditions), oil comes from the oil pan (6) through the suction bell (9) to the oil pump (7). When the oil is cold, an oil pressure difference in bypass valves (5) and (8) will cause the bypass valves to open. These bypass valves give immediate lubrication to all components when cold oil with high viscosity causes a restriction to the oil flow through the oil cooler (10) and oil filter (4). The oil pump then sends the cold oil through the bypass valve (8) for the oil cooler and through the bypass valve (5) for the oil filter, to the oil manifold (1) in the cylinder block and to the supply line (2) for the turbocharger. Oil from the turbocharger goes back through the oil return line (3) to the oil pan.

When the oil gets warm, the pressure difference in the bypass valves decrease and the bypass valves close. Now there is a normal oil flow through the oil cooler and oil filter.


FLOW OF OIL (ENGINE WARM)
1. Oil manifold in cylinder block. 2. Oil supply line to turbocharger. 3. Oil return line from turbocharger. 4. Oil filter. 5. Bypass valve for the oil filter. 6. Oil pan. 7. Oil pump. 8. Bypass valve for the oil cooler. 9. Suction bell. 10. Oil cooler.


FLOW OF OIL (ENGINE COLD)
1. Oil manifold in cylinder block. 2. Oil supply line to turbocharger. 3. Oil return line from turbocharger. 4. Oil filter. 5. Bypass valve for the oil filter. 6. Oil pan. 7. Oil pump. 8. Bypass valve for the oil cooler. 9. Suction bell. 10. Oil cooler.

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

Oil Flow In The Engine

From the oil manifold (16) in the cylinder block, oil is sent through drilled passages in the cylinder block that connect the main bearings (15) and the camshaft bearings (13). Oil goes through drilled holes in the crankshaft to give lubrication to the connecting rod bearings. A small amount of oil is sent through oil jet tubes (14) to make the pistons cooler. Earlier engines do not have oil jet tubes (14). Those engines have orifices near the main bearings. A small amount of oil is sent through the orifices to make the pistons cooler. Oil goes through grooves in the bores for the front and rear camshaft bearings and then into passages (3) that connects the valve lifter bores (4). These passages give oil under pressure for the lubrication of the valve lifters.

Oil is sent through passages (12) and (10) to the mounting hole for the rear bracket (1) for the rocker arm shaft. Oil is also sent through passages (8) and (7) to the mounting hole for the front bracket (6) for the rocker arm shaft. Then oil goes up the mounting holes for the front and rear brackets for the rocker arm shaft and into the rocker arm shafts (2) and (5). Holes in the rocker arm shafts lets the oil give lubrication to the valve system components in the cylinder head.

The air compressor gets oil from passage (7) in the cylinder block, through passages in the timing gear housing and the accessory drive gear.

The idler gear gets oil from passage (9) in the cylinder block through a passage in the shaft for the idler gear installed on the front of the cylinder block.

The fuel injection pump and governor gets oil from passage (11) in the cylinder block. The automatic timing advance unit gets oil from the fuel injection pump through the drive shaft for the fuel injection pump.


OIL FLOW IN THE ENGINE
1. Bracket for the rocker arm shaft. 2. Rocker arm shaft. 3. Oil passage to valve lifters. 4. Valve lifter bore. 5. Rocker arm shaft. 6. Bracket for the rocker arm shaft. 7. Oil passage to head and accessory drive. 8. Oil passage to head. 9. Oil passage to idler gear shaft. 10. Oil passage to head. 11. Oil passage to the fuel injection pump and governor. 12. Oil passage to head. 13. Camshaft bearing. 14. Oil jet tubes. 15. Main bearing. 16. Oil manifold. 17. Oil passage from the oil pump to the oil cooler and filter. 18. Oil passage from the oil cooler and filter.

There is a pressure control valve in the oil pump. This valve controls the pressure of the oil coming 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 valve will open. This allows the oil that is not needed to go back to the inlet oil passage of the oil pump.

After the lubricating oil has done its work, it goes back to the engine oil pan.

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) the water pump (9) sends coolant through the oil cooler (12) and into the cylinder block (11). Coolant moves through the cylinder block into the cylinder head (5) and then goes to the housing for the temperature regulator (2). The temperature regulator is open and the coolant goes through the outlet hose (3) to the radiator (10). The coolant is made cooler as it moves through the radiator. When the coolant gets to the bottom of the radiator, it goes through the inlet hose (13) and into the water pump.

When the engine is cold, the water temperature regulator (2) is closed, and the coolant is stopped from going to the radiator. The coolant goes from the housing for the temperature regulator back to the water pump (9) through water elbow (8).

NOTE: The water temperature regulator (2) is an important part of the cooling system. If the water temperature regulator is not installed in the system, the coolant will not go through the radiator and overheating (engine runs too hot) will be the result.

On an engine with an aftercooler, a small amount of coolant comes out of the bonnet for the oil cooler and goes through tube (6) to the aftercooler (1). This coolant goes through the aftercooler and out elbow (7) and back into the cylinder block.


RADIATOR COOLED SYSTEM (ENGINE WARM)
1. Aftercooler. 2. Water temperature regulator. 3. Outlet hose. 4. Radiator cap. 5. Cylinder head. 6. Tube to aftercooler. 7. Elbow from aftercooler. 8. Water elbow. 9. Water pump. 10. Radiator. 11. Cylinder block. 12. Oil cooler. 13. Inlet hose.

Keel Cooled System


KEEL COOLED SYSTEM (ENGINE WARM)
1. Water cooled turbocharger. 2. Tube. 3. Elbow. 4. Aftercooler. 5. Water cooled exhaust manifold. 6. Cylinder head. 7. Outlet pipe. 8. Pipe. 9. Temperature regulator housing. 10. Pressure cap. 11. Expansion tank. 12. Tube. 13. Water pump. 14. Elbow. 15. Tube. 16. Inlet line. 17. Tube. 18. Outlet line. 19. Cylinder block. 20. Marine gear oil cooler. 21. Engine oil cooler. 22. Keel cooler.

In normal operation (engine warm) the water pump (13) sends coolant through the engine oil cooler (21), marine gear oil cooler (20), and into the cylinder block (19). Coolant moves through the cylinder block into the cylinder head (6) and then goes through outlet pipe (7) and into the outlet line (18). The coolant then goes through the outlet line to the keel cooler (22) where the coolant is made cooler. From the keel cooler, the coolant goes through the inlet line (16) through the temperature regulator housing (9) and into the expansion tank (11). The coolant from the expansion tank goes through tube (15) and back into the water pump.

When the engine is cold, the water temperature regulator (9) lets the coolant from the cylinder head (6) go through pipe (8) and into the expansion tank (11). From the expansion tank, the coolant goes through tube (15) and back into the water pump. The coolant is not sent through the keel cooler until the engine is warm.

NOTE: The water temperature regulator (9) is an important part of the cooling system. If the water temperature regulator is not installed in the system, the coolant will not go through the keel cooler and overheating (engine runs too hot) will be the result.

Pressure cap (10) is used to keep the correct pressure in the cooling system. This pressure keeps a constant supply of coolant to the water pump. If this pressure goes too high, a valve in the pressure cap moves (opens) to get a reduction of pressure. When the correct pressure is in the cooling system, the valve in the pressure cap moves down (to the closed position).

On an engine with an aftercooler, a small amount of coolant comes out of the bonnet for the oil cooler and goes through tube (12) to the aftercooler (4). This coolant goes through the aftercooler and out elbow (14) and back into the cylinder block.

Some engines are equipped with a water cooled exhaust manifold (5) and a water cooled turbocharger (1). The coolant for the exhaust manifold comes from the back of the cylinder head (6) through elbow (3) and goes out of the manifold through the outlet pipe (7). The coolant for the turbocharger comes from the bonnet for the marine gear oil cooler (20) through tube (17) to the turbocharger. The coolant goes out of the turbocharger through tube (2) and into the water cooled exhaust manifold.

Heat Exchanger Cooled System


HEAT EXCHANGER COOLED SYSTEM (ENGINE WARM)
1. Water cooled turbocharger. 2. Tube. 3. Elbow. 4. Water cooled exhaust manifold. 5. Cylinder head. 6. Outlet pipe. 7. Pipe. 8. Outlet line. 9. Temperature regulator housing. 10. Pressure cap. 11. Expansion tank. 12. Inlet pipe. 13. Water pump. 14. Tube. 15. Heat exchanger. 16. Cylinder block. 17. Marine gear oil cooler. 18. Engine oil cooler. 19. Tube. 20. Pump.

In normal operation (engine warm) the water pump (13) sends coolant through the engine oil cooler (18), marine gear oil cooler (17), and into the cylinder block (16). Coolant moves through the cylinder block into the cylinder head (5) and then goes through outlet pipe (6) and into the outlet line (8). The coolant then goes through the outlet line to the heat exchanger (15) where the coolant is made cooler. From the heat exchanger, the coolant goes through the inlet line (12) through the temperature regulator housing (9) and into the expansion tank (11). The coolant from the expansion tank goes through tube (19) and back into the water pump.

When the engine is cold, the water temperature regulator (9) lets the coolant from the cylinder head (5) go through pipe (7) and into the expansion tank (11). From the expansion tank, the coolant goes through tube (19) and back into the water pump (13). The coolant is not sent through the heat exchanger until the engine is warm.

NOTE: The water temperature regulator (9) is an important part of the cooling system. If the water temperature regulator is not installed in the system, the coolant will not go through the heat exchanger and overheating (engine runs too hot) will be the result.

Pressure cap (10) is used to keep the correct pressure in the cooling system. This pressure keeps a constant supply of coolant to the water pump. If this pressure goes too high, a valve in the pressure cap moves (opens) to get a reduction of pressure. When the correct pressure is in the cooling system, the valve in the pressure cap moves down (to the closed position).

Sea water or water from a cooling tower is sent through the heat exchanger (15) by the pump (20). This water makes the heat exchanger cooler.

Some engines are equipped with a water cooled exhaust manifold (4) and a water cooled turbocharger (1). The coolant for the exhaust manifold comes from the back of the cylinder head (5) through elbow (3) and goes out of the manifold through the outlet pipe (6). The coolant for the turbocharger comes from the bonnet for the marine gear oil cooler (17) through tube (14) to the turbocharger. The coolant goes out of the turbocharger through tube (2) and into the water cooled exhaust manifold.

Coolant Conditioner (An Attachment)


COOLING SYSTEM WITH COOLANT CONDITIONER
1. Cylinder liner. 2. Coolant bypass line. 3. Coolant outlet (to radiator). 4. Radiator. 5. Temperature regulator. 6. Water pump. 7. Coolant conditioner element. 8. Engine oil cooler. 9. Coolant inlet (from radiator).

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 thru lines from the water pump to the base and back to the block or to the air compressor (if so equipped). There is a constant flow of coolant thru the element.

The element has a specific amount of inhibitor for acceptable cooling system protection. As coolant flows thru 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 "PRECHARGE" element has more than the normal amount of inhibitor, and is used when a system is first filled with new coolant. 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 intervals to give protection to the cooling system.


NOTICE

Do not use Dowtherm 209 Full-Fill in a cooling system that has a coolant conditioner. These two systems are not compatible (corrosion inhibitor is reduced) when used together.


Basic Block

Vibration Damper

The twisting of the crankshaft, due to the regular power impacts along its length, is called twisting (torsional) vibration. The 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.


CROSS SECTION OF A VIBRATION DAMPER (Typical Example)
1. Flywheel ring. 2. Rubber ring. 3. Inner hub.

The damper is made of a flywheel ring (1) connected to an inner hub (3) by a rubber ring (2). The rubber makes a flexible coupling between the flywheel ring and the inner hub.

Crankshaft

The crankshaft changes the combustion forces in the cylinder into usable rotating torque which powers the machine. There is a gear at the front of the crankshaft to drive the timing gears and the oil pump.

The crankshaft is supported by seven main bearings. Pressure oil is supplied to all bearing surfaces through drilled holes in the crankshaft.

Lip seals and wear sleeves are used at both ends of the crankshaft for easy replacement and a reduction of maintenance cost.

Camshaft

This engine uses a single, forged camshaft that is driven at the front end and is supported by seven bearings. Each lobe on the camshaft moves a roller follower, which in turn moves a push rod and two valves (either exhaust or intake) for each cylinder.

Cylinder Block And Liners

A steel spacer plate is used between the cylinder heads and the block to eliminate liner counterbore and to provide maximum liner flange support area (the liner flange sits directly on the cylinder block).

Engine coolant flows around the liners to cool them. Three O-ring seals at the bottom and a filler band at the top of each cylinder liner form a seal between the liner and the cylinder block.

Pistons, Rings And Connecting Rods

The cast aluminum piston has 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 and seat in an iron band that is cast into the piston. KEYSTONE rings have a tapered shape and the movement of the rings in the piston groove (also of tapered shape) results in a constantly changing clearance (scrubbing action) between the ring and the groove. This action results in a reduction of carbon deposit and possible sticking of rings.

The oil ring is a standard (conventional) type and is spring loaded. Holes in the oil ring groove provide for the return of oil to the crankcase.

The direct injection piston has a full skirt and uses a special shape (cardioid design) of the top surface to help combustion efficiency.

The prechamber piston uses a partial skirt and has a steel heat plug mounted in the pocket (crater) on top of the piston. This plug protects the top of the piston from erosion and burning.

The full floating piston pin is retained by two snap rings which fit in grooves in the pin bore.

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

Electrical System

The electrical system has three separate circuits: the charging circuit, the starting circuit and the lighting circuit. Some of the electrical system components are used in more than one circuit. The battery (batteries), disconnect switch, 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.


NOTICE

The disconnect switch, if so equipped, must be in the ON position to let the electrical system function. There will be damage to some of the charging circuit components if the engine is running with the disconnect switch in the OFF position.


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.

The starting circuit of a "PC" engine can have a glow plug for each cylinder. 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 through the ammeter. The starting circuit is not connected through 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 (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 has 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.


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

Voltage 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 winding, 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.

Starting Motor

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

The starting 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 starting motor. When the circuit between the battery and the starting motor is complete, the pinion will turn the engine flywheel. A clutch gives protection for the starting motor so that the engine can not turn the starting motor too fast. When the start switch is released, the starter pinion will move away from the ring gear.


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

Other Components

Circuit Breaker

The circuit breaker is a safety 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 circuit 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.


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

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

A number of electrical systems can be used with these engines. Some systems are available with one 32 volt, 24 volt or 12 volt starting motor. With a 30 volt (15 cell battery) system, use the 32 volt diagram. Systems with no electric starting motors use air starting motors.

When so equipped, the starting circuit has a glow plug for each cylinder of the diesel engine. These diagrams show only the HEAT-START switch with glow plugs. Systems with no glow plugs use a push button switch with two post connections to activate the starter solenoid.

A fuel pressure switch in some systems breaks the circuit to the alternator field. This switch prevents damage to the alternator from the battery when the engine is not operating.

Automatic START-STOP wiring diagrams are shown for the complete system in the ATTACHMENT section of this manual.

Negative Ground Systems

These systems are used in applications when it is not necessary to prevent radio distortion and/or chemical changes (electrolysis) of grounded components.


NEGATIVE GROUND 24V: 60 AMP. AND 32V: 60 AMP. SYSTEM WITH GLOW PLUGS (DELCO-REMY)
1. Heat-start switch. 2. Ammeter. 3. Glow plugs. 4. Alternator. 5. Starting motor. 6. Battery.


NEGATIVE GROUND 24V: 35 AMP. SYSTEM WITH GLOW PLUGS (MOTOROLA)
1. Heat-start switch. 2. Ammeter. 3. Glow plugs. 4. Regulator. 5. Pressure switch. 6. Starting motor. 7. Battery. 8. Alternator. 9. Output connection. 10. Field connections. 11. Ground connection.


NEGATIVE GROUND 24V: 60 AMP. OR 32V: 60 AMP. SYSTEM WITH GLOW PLUGS FOR USE WITH AIR STARTING (DELCO-REMY)
1. Heat-start switch. 2. Ammeter. 3. Glow plugs. 4. Alternator. 5. Battery.


NEGATIVE GROUND 24V: 35 AMP. SYSTEM WITH GLOW PLUGS FOR USE WITH AIR STARTING (MOTOROLA)
1. Heat-start switch. 2. Ammeter. 3. Glow plugs. 4. Regulator. 5. Pressure switch. 6. Battery. 7. Alternator. 8. Output connection. 9. Field connections. 10. Ground connection.

Insulated Systems

These systems are most often used in applications where radio interference is not desired or where conditions are such that grounded components will have corrosion from chemical change (electrolysis).


INSULATED 24V: 60 AMP. OR 32V: 60 AMP. SYSTEM WITH GLOW PLUGS (DELCO-REMY)
1. Heat-start switch. 2. Magnetic switch. 3. Glow plugs. 4. Ammeter. 5. Alternator. 6. Starting motor. 7. Battery.


INSULATED 24V: 35 AMP. SYSTEM WITH GLOW PLUGS (MOTOROLA)
1. Heat-start switch. 2. Magnetic switch. 3. Glow plugs. 4. Regulator. 5. Ammeter. 6. Starting motor. 7. Pressure switch. 8. Battery. 9. Alternator. 10. Output connection. 11. Field connections. 12. Negative connection.


INSULATED 24V: 60 AMP. OR 32V: 60 AMP. SYSTEM WITH GLOW PLUGS FOR USE WITH AIR STARTING (DELCO-REMY)
1. Heat-start switch. 2. Magnetic switch. 3. Glow plugs. 4. Ammeter. 5. Alternator. 6. Battery.


INSULATED 24V: 35 AMP. SYSTEM WITH GLOW PLUGS FOR USE WITH AIR STARTING (MOTOROLA)
1. Heat-start switch. 2. Magnetic switch. 3. Glow plugs. 4. Regulator. 5. Ammeter. 6. Pressure switch. 7. Battery. 8. Alternator. 9. Output connection. 10. Field connections. 11. Negative connection.

Air Starting System

The air starting motor is installed on the flywheel housing of the engine. Air for the starting motor comes from a separate air compressor system and is sent thru a pressure regulator. From the pressure regulator, air goes thru hose (6) to tee (4).


AIR STARTING SYSTEM
1. Lubricator. 2. Valve. 3. Line. 4. Tee. 5. Starter control. 6. Hose. 7. Starting motor. 8. Deflector. 9. Line. 10. Drive housing. 11. Line.

Line (3) sends air from the tee to the starter control valve (5). When the starter control is pushed, air is sent from the starter control valve thru line (11) to the drive housing (10). This air causes the pinion gear to engage with the ring gear of the flywheel.

After the pinion gear is engaged, air goes from the drive housing thru line (9) to valve (2). This air opens valve (2) and lets the main air supply from tee (4) go thru the lubricator (1) and into the starting motor (7).

This air pressure puts a force on the vanes of the rotor and causes the rotor to turn. The air then goes out of the starting motor thru the deflector (8).


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

Lubricator

A small tube in the main air passage puts air pressure over the oil in the bowl. This air pressure causes the oil to go from the bowl to a chamber above the main air passage. Oil goes into the main air passage at a rate of approximately four drops per minute.

As the main air supply goes thru the lubricator, this small amount of oil is mixed with it. This oil gives lubrication to the rotor and vanes of the air motor.

Caterpillar Information System:

3406 INDUSTRIAL & MARINE ENGINES Pressure Regulating Valve For Air Starting Motor
3406 INDUSTRIAL & MARINE ENGINES Air Starting Motor 4N4368, 6N1633, 6N4147, 6N9131 (Ingersoll-Rand Number 150 BMP-E78RH-54)
3406 INDUSTRIAL & MARINE ENGINES Connection For Glow Plug Wiring
3406 INDUSTRIAL & MARINE ENGINES Service Meter And Tachometer Drive
3406 INDUSTRIAL & MARINE ENGINES Pressure Switch
3406 INDUSTRIAL & MARINE ENGINES Starter Switch
3406 INDUSTRIAL & MARINE ENGINES Shut-Off Solenoids
3406 INDUSTRIAL & MARINE ENGINES Starter Solenoids
3406 INDUSTRIAL & MARINE ENGINES Starter Motors
3406 INDUSTRIAL & MARINE ENGINES Alternator Regulator
3406 INDUSTRIAL & MARINE ENGINES Alternators 2N6398 24V (Motorola Number MH24-902A, 8MH3005F); 2N6397 24V (Motorola Number MA24-902A, 8MA3006F)
3406 INDUSTRIAL & MARINE ENGINES Alternators And Regulators
3406 INDUSTRIAL & MARINE ENGINES Testing And Adjusting
3406 INDUSTRIAL & MARINE ENGINES Introduction
3406 INDUSTRIAL & MARINE ENGINES Woodward PSG Governor
3406 INDUSTRIAL & MARINE ENGINES Governor Linkage
3406 INDUSTRIAL & MARINE ENGINES Governor Air Actuator
3406 INDUSTRIAL & MARINE ENGINES Oil Pressure Switch 2N7744 Switch (Texas Instrument No. 20PS66-1)
3406 INDUSTRIAL & MARINE ENGINES Pressure Switch 2L3402 Switch
3406 INDUSTRIAL & MARINE ENGINES Governor Controls
3406 INDUSTRIAL & MARINE ENGINES Air Fuel Ratio Controls
3406 INDUSTRIAL & MARINE ENGINES Radiators (4N3014, 4N3015, 4N3016, 4N3023)
3406 INDUSTRIAL & MARINE ENGINES Primary Fuel Filter
3406 INDUSTRIAL & MARINE ENGINES Flywheels
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