3406C GENERATOR SET ENGINE Caterpillar


Systems Operation

Usage:



Introduction

NOTE: For Specifications with illustrations, make reference to Specification For 3406C Generator Set Engines, RENR1292. If the Specifications in RENR1292 are not the same as the Systems Operation and the Testing & Adjusting, look at the printing date on the front cover of each book. Use the Specifications given in the book with the latest date.

Engine Design


Cylinder and Valve Location

Bore ... 137 mm (5.4 in)

Stroke ... 165 mm (6.5 in)

Displacement ... 14.6 liter (893 cu in)

Number and Arrangement of Cylinders ... 6, In-line

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

Rotation of Crankshaft (when viewed from flywheel end) ... Counterclockwise

Rotation of Fuel Pump Camshaft (when viewed 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.

Fuel System

Fuel Flow


Fuel System Schematic
(1) Fuel injection nozzle. (2) Fuel injection lines. (3) Fuel return line. (4) Constant bleed orifice (part of the elbow). (5) Fuel injection pump housing. (6) Fuel priming pump. (7) Check valves. (8) Fuel transfer pump. (9) Fuel tank. (10) Primary fuel filter. (11) Secondary fuel filter.

Fuel is pulled from fuel tank (9) through primary fuel filter (10) by fuel transfer pump (8). From the fuel transfer pump the fuel is pushed through secondary fuel filter (11) and to the fuel manifold in fuel injection pump housing (5). Fuel pressure in the fuel manifold is determined by the fuel transfer pump spring. A constant bleed orifice is in the fuel return line elbow.

Constant bleed orifice (4) lets a constant flow of fuel go through fuel return line (3) back to fuel tank (9). This helps keep the fuel cool and free of air. The individual fuel injection pumps get fuel from the fuel manifold and push fuel at a very high pressure through fuel injection lines (2) to fuel injection nozzles (1). Each fuel injection nozzle has very small holes in the tip that change the flow of fuel to a very fine spray that gives good fuel combustion in the cylinder.

Fuel Injection Pump

The fuel injection pump increases the pressure of the fuel and sends an exact amount of fuel to the fuel injection nozzle. There is one fuel injection pump for each cylinder in the engine.


Fuel Injection Pump
(1) Spill port. (2) Check valve. (3) Pump barrel. (4) Bypass port. (5) Pump plunger. (6) Spring. (7) Fuel rack. (8) Gear. (9) Lifter. (10) Cam.

The fuel injection pump is moved by cam (10) of the fuel pump camshaft. When the camshaft turns, the cam raises lifter (9) and pump plunger (5). The pump plunger always makes a full stroke. As the camshaft turns farther, spring (6) returns the pump plunger and lifter to the bottom of the stroke.


Pump Barrel And Plunger Assembly
(1) Spill port. (2) Check valve. (3) Pump barrel. (4) Bypass port. (5) Pump plunger. (11) Orificed reverse flow check valve. (12) Spring. (13) Spring. (14) Scroll. (15) Slot.

When the pump plunger is at the bottom of the stroke, fuel at transfer pump pressure flows through spill port (1) and bypass port (4). Fuel fills pump barrel (3) in the area above pump plunger (5).


Pump Barrel And Plunger Assembly
(1) Spill port. (2) Check valve. (3) Pump barrel. (4) Bypass port. (5) Pump plunger. (11) Orificed reverse flow check valve. (12) Spring. (13) Spring. (14) Scroll. (15) Slot.

After pump plunger (5) begins the up stroke, fuel will be pushed out bypass port (4) until the top of the pump plunger closes the port. As the pump plunger travels farther up, the pressure of the fuel increases. At approximately 690 kPa (100 psi), check valve (2) opens and lets fuel flow into the fuel injection line to the fuel injection nozzle.


Pump Barrel And Plunger Assembly
(1) Spill port. (2) Check valve. (3) Pump barrel. (4) Bypass port. (5) Pump plunger. (11) Orificed reverse flow check valve. (12) Spring. (13) Spring. (14) Scroll. (15) Slot.

When the pump plunger travels farther up, scroll (14) uncovers spill port (1). The fuel above the pump plunger goes through slot (15), along the edge of scroll (14) and out spill port (1) back to the fuel manifold. This is the end of the injection stroke. The pump plunger can have more travel up, but no more fuel will be sent to the fuel injection nozzle.


Pump Barrel And Plunger Assembly
(1) Spill port. (2) Check valve. (4) Bypass port. (5) Pump plunger. (11) Orificed reverse flow check valve. (12) Spring. (13) Spring. (14) Scroll. (15) Slot.

When spill port (1) is opened by pump plunger (5) the fuel nozzle closes and spring (13) closes check valve (2) as the pressure above pump plunger (5) drops below 690 kPa (100 psi). At the same time the orificed reverse flow check valve (11) opens.

Orificed reverse flow check valve (11) closes when the fuel pressure in the fuel injection lines is 6900 kPa (1000 psi). This keeps the fuel in the injection line and above the reverse flow check valve at 6900 kPa (1000 psi).

NOTE: Orificed reverse flow check valve (11) prevents rough idle by stopping any secondary injection of fuel between injection strokes. This valve is only effective below 8250 kPa (1200 psi) and has no effect above that pressure. When the engine is shutdown, the pressure is gradually released through a small groove on the bottom face of orificed reverse flow check valve (11).

When the pump plunger travels down and uncovers bypass port (4), fuel begins to fill the area above the pump plunger again, and the pump is ready to begin another stroke.

The amount of fuel the injection pump sends to the fuel injection nozzle on each pump stroke can be changed by the rotation of the pump plunger. Gear (8) is attached to the pump plunger and is in mesh with fuel rack (7). The governor moves the fuel rack which turns the fuel pump plungers according to the fuel needs of the engine. When the governor turns the pump plunger, scroll (14) on the plunger changes the distance between the top of pump plunger and the point where scroll (14) uncovers spill port (1). The longer the distance from the top of the pump plunger to the point where scroll (14) uncovers spill port (1), the more fuel will be injected.

To stop the engine, the pump plunger is rotated so that slot (15) on the pump plunger is in line with spill port (1). The fuel will now go out the spill port and not to the fuel injection nozzle.

Fuel Injection Nozzle

The fuel injection nozzle is installed in an adapter in the cylinder head and extended into the combustion chamber. The fuel injection pump sends high pressure fuel 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 of the nozzle adapter.

High pressure fuel from the fuel injection pump goes into inlet passage (5). Fuel then goes through 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.

Fuel Transfer Pump

The fuel transfer pump is a piston pump that is moved by a cam (eccentric) on the camshaft for the fuel injection pump. The transfer pump is located on the bottom side of the fuel injection pump housing.


Fuel Transfer Pump (Start Of Down Stroke) (Arrows Indicate Fuel Flow Direction)
(1) Push rod. (2) Piston. (3) Outlet check valve. (4) Pumping check valve. (5) Pumping spring. (6) Pump inlet port. (7) Inlet check valve. (8) Pump outlet port.

When the fuel injection pump camshaft turns, the cam moves push rod (1) and piston (2) down. As the piston moves down, inlet check valve (7) and outlet check valve (3) close. Pumping check valve (4) opens and allows the fuel below the piston to move into the area above the piston. Pumping spring (5) is compressed as the piston is pushed down by push rod (1).


Fuel Transfer Pump (Start Of Up Stroke) (Arrows Indicate Fuel Flow Direction)
(1) Push rod. (2) Piston. (3) Outlet check valve. (4) Pumping check valve. (5) Pumping spring. (6) Pump inlet port. (7) Inlet check valve. (8) Pump outlet port.

As the fuel injection pump camshaft continues to turn, the cam no longer puts force on push rod (1). Pumping spring (5) now moves piston (2) up. This causes pumping check valve (4) to close. Inlet check valve (7) and outlet check valve (3) will open. As the piston moves up, the fuel in the area above the piston is pushed through the outlet check valve (3) and out pump outlet port (8). Fuel also moves through pump inlet port (6) and inlet check valve (7) to fill the area below piston (2). The pump is now ready to start a new cycle.

Oil Flow For Fuel Injection Pump And Governor


Fuel Injection Pump And Governor
(1) Servo. (2) Fuel injection pump housing. (3) Cover. (4) Oil supply port (from cylinder block). (5) Oil drain port (into cylinder block). (6) Dashpot. (7) Governor rear housing. (8) Governor center housing.

Lubrication oil from the side of the cylinder block goes into the side of the fuel injection pump housing at location (4). The oil then goes to a passage between fuel injection pump housing (2) and governor center housing (8) where it flows to three different locations.

A part of the oil goes back into the main oil passage in fuel injection pump housing (2). This oil gives a supply of lubrication for the three fuel injection pump camshaft bearings. At the camshaft bearing next to the governor, oil flows into drilled passages in the camshaft to give lubrication to the flyweight carrier thrust bearing. Oil drains from the camshaft bearings into the fuel injection pump housing. A drain hole in the housing keeps the level of oil in the housing even with the center of the camshaft. Oil drains from the housing, through oil drain port (5), back to the engine block.

Oil also flows through a different passage back to the fuel injection pump housing. This passage is connected to governor servo (1). The governor servo gives hydraulic assistance to move the fuel rack.

The remainder of the oil goes through a passage in the governor center housing (8) and governor rear housing (7) to cover (3) or the fuel ratio control. From the cover or the fuel ratio control, oil drains back into the governor housing. This oil lubricates the governor control components and supplies the oil for the dashpot (6). The internal parts of the governor are also lubricated by oil leakage from governor servo (1) and the oil thrown off by parts in rotation. An opening between the lower part of the governor and the fuel injection pump housing lets oil out of the governor. The fuel injection pump housing has an oil drain port (5) that is connected to the engine block.

Governor


Governor
(1) Governor spring. (2) Sleeve. (3) Valve. (4) Piston. (5) Governor servo. (6) Fuel rack. (7) Lever. (8) Flyweights. (9) Load stop bar. (10) Stop bar. (11) Riser. (12) Spring seat. (13) Torque rise setting screw. (14) Stop bolt. (15) Torque spring. (16) Fuel setting screw. (17) Stop collar.

The governor controls the amount of fuel needed by the engine to maintain a desired rpm.

The governor flyweights (8) are driven directly by the fuel pump camshaft. Riser (11) is moved by flyweights (8) and governor spring (1). Lever (7) connects the riser with sleeve (2) which is fastened to valve (3). Valve (3) is a part of governor servo (5) and moves piston (4) and fuel rack (6). The fuel rack moves toward the front of the fuel pump housing (to the right in the illustration) when moved in the FUEL OFF direction.

The force of governor spring (1) always pushes to give more fuel to the engine. The centrifugal (rotating) force of flyweights (8) always push to get a reduction of fuel to the engine. When these two forces are in balance (equal), the engine runs at a constant rpm.

When the governor control lever is moved to the high idle position, governor spring (1) is put in compression and pushes riser (11) toward the flyweights. When the riser moves forward, lever (7) moves sleeve (2) toward the rear. Sleeve (2) moves valve (3) through the broken link spring. Valve (3) stops oil flow through governor servo (5) and the oil pressure moves piston (4) and the fuel rack to the rear. This increases the amount of fuel to the engine. As engine speed increases, the flyweight force increases and moves the riser toward the governor spring. When the riser moves to the rear, lever (7) moves sleeve (2) and valve (3) forward. Valve (3) now directs oil pressure to the rear of piston (4) and moves the piston and fuel rack forward. This decreases the amount of fuel to the engine. When the flyweight force and the governor spring force become equal, the engine speed is constant and the engine runs at high idle rpm. High idle rpm is adjusted by the high idle adjustment screw. The adjustment screw limits the amount of compression of the governor spring.

With the engine at high idle, when the load is increased, engine speed will decrease. Flyweights (8) move in and governor spring (1) pushes riser (11) forward and increases the amount of fuel to the engine. As the load is increased more, governor spring (1) pushes riser (11) farther forward. Spring seat (12) also pushes on stop bolt (14). On the opposite end of stop bolt (14) is stop collar (17) which has fuel setting screw (16) and torque rise setting screw (13). Torque rise setting screw (13) controls the maximum amount of fuel rack travel. As stop bolt (14) moves forward fuel setting screw (16) moves forward to make full contact with torque spring (15) at the full load speed of the engine. The adjustment of fuel setting screw (16) controls the horsepower of the engine at full load speed. Torque spring (15) now acts to control the fuel rack movement.

If more load is added, the engine will run in a lug condition. This occurs when the load placed on the engine is greater than the horsepower output at the full load speed. When rpm decreases because of added load, the force of governor spring (1) moves riser (11) farther forward. As stop bolt (14) moves forward, fuel setting screw (16) bends torque spring (15) and fuel rack (6) can move farther in the FUEL ON direction. This movement is stopped when torque rise setting screw (13) contacts stop bar (10). This is the maximum fuel setting position. The adjustment of torque rise setting screw (13) controls the additional amount of fuel rack travel below full load speed as the peak torque speed of the engine is reached.

Also, the engine can be shutdown if the mechanical action of governor spring (1) and flyweights (8) become bound (stuck) in the FUEL ON position. Shutdown can be done by use of the shutoff solenoid or by moving the manual shutoff lever (if equipped) to the off position. Valve (3) will move independent of sleeve (2) to push fuel rack (6) to the FUEL OFF position. Note that the broken link spring is compressed as valve (3) slides in sleeve (2).

Governor Servo


Governor Servo (Fuel on direction)
(1) Valve. (2) Piston. (3) Cylinder. (4) Cylinder sleeve. (5) Fuel rack. (A) Oil inlet. (B) Oil outlet. (C) Oil passage. (D) Oil passage.

The governor servo gives hydraulic assistance to the mechanical governor force to move the fuel rack. The governor servo has cylinder (3), cylinder sleeve (4), piston (2) and valve (1).

When the governor moves in the FUEL ON direction, valve (1) moves to the left. The valve opens oil outlet (B) and closes oil passage (D). Pressure oil from oil inlet (A) pushes piston (2) and fuel rack (5) to the left. Oil behind the piston goes through oil passage (C), along valve (1) and out oil outlet (B).


Governor Servo (Balanced position)
(1) Valve. (2) Piston. (3) Cylinder. (4) Cylinder sleeve. (5) Fuel rack. (A) Oil inlet. (B) Oil outlet. (C) Oil passage. (D) Oil passage.

When the governor spring and flyweight forces are balanced and the engine speed is constant, valve (1) stops moving. Pressure oil from oil inlet (A) pushes piston (2) until oil passages (C and D) are opened. Oil now flows through oil passage (D) along valve (1) and out through oil outlet (B). With no oil pressure on the piston, the piston and fuel rack (5) stop moving.


Governor Servo (Fuel Off direction)
(1) Valve. (2) Piston. (3) Cylinder. (4) Cylinder sleeve. (5) Fuel rack. (A) Oil inlet. (B) Oil outlet. (C) Oil passage. (D) Oil passage.

When the governor moves in the FUEL OFF direction, valve (1) moves to the right. The valve closes oil outlet (B) and opens oil passage (D). Pressure oil from oil inlet (A) is now on both sides of piston (2). The area of the piston is greater on the left side than on the right side of the piston. The force of the oil is also greater on the left side of the piston and moves the piston and fuel rack (5) to the right.

Dashpot


Dashpot
(1) Needle valve. (2) Oil reservoir. (3) Cylinder. (4) Piston. (5) Dashpot spring. (6) Spring seat.

The dashpot helps give the governor better speed control when there are sudden speed and load changes. The dashpot has needle valve (1), oil reservoir (2), cylinder (3), piston (4), dashpot spring (5) and spring seat (6). Piston (4) and spring seat (6) are fastened to dashpot spring (5).

When spring seat (6) is moved, by a change in load or speed, dashpot spring (5) moves piston (4) in cylinder (3). The cylinder and oil reservoir (2) are full of oil. As piston (4) moves, it causes oil to be moved in or out of the cylinder through needle valve (1) and oil reservoir (2).

Needle valve (1) gives restriction to oil flow to and from cylinder (3). This causes a restriction to the movement of piston (4) and spring seat (6). The faster the governor tries to move spring seat (6), the greater the resistance the dashpot gives to the spring seat movement.

Automatic Timing Advance Unit


4W4619 Automatic Timing Advance Unit (Before Timing Advance Begins)
(1) Spring. (2) Flyweights. (3) Timing gear. (4) Carrier. (5) Fuel injection pump camshaft. (6) Screw. (7) Setscrew. (8) Spring. (9) Bolt. (10) Ring. (11) Ring. (12) Spool. (13) Body.

The automatic timing advance unit connects the drive end of the fuel injection pump camshaft with the timing gears in the front of the engine. The unit uses the engines oil pressure to change the fuel injection timing according to engine speed. This gives better combustion of the fuel at all levels of engine operation.

The automatic timing advance unit is connected to fuel injection pump camshaft (5) with four bolts (9). Bolts (9) pull rings (10) and (11) together to hold timing gear (3). Carrier (4) has straight splines on its inside diameter. The outer splines are in contact with the straight splines of ring (10) and the inner splines are in contact with helical splines on fuel injection pump camshaft (5). When the engine is started, timing gear (3) drives fuel injection pump camshaft (5) through ring (10) and carrier (4).

As the engine is run at a steady rpm (such as low idle speed), the centrifugal force of flyweight (2) and the force of spring (8) are equal. At this point, spool (12) is held in position to close the oil passage in body. Engine lubrication oil flows through the fuel injection pump housing and through a passage in fuel injection pump camshaft (5) into body (13) and is stopped by spool (12). At this point the oil cannot move body (13) and carrier (4). Spring (1) holds carrier (4) toward the fuel injection pump and the fuel injection timing is not advanced.


Automatic Timing Advance Unit (Timing Advance Begins)
(1) Spring. (2) Flyweights. (3) Timing gear. (4) Carrier. (5) Fuel injection pump camshaft. (6) Screw. (7) Setscrew. (8) Spring. (9) Bolt. (10) Ring. (11) Ring. (12) Spool. (13) Body.

When the engine speed increases to the point where the force of flyweights (2) is greater than the force of spring (8), the flyweights move spool (12) to the left. This is the start of advance. The rpm at which advance starts is adjusted by screw (6). Screw (6) controls the force of spring (8). The spool opens ports in body (13) which allows engine lubrication oil to flow out of camshaft (5) through the body and put oil pressure on body (13) and carrier (4). When the pressure of the oil becomes greater than the force of spring (1), the body and carrier begin to move to the left. Carrier (4) has straight splines on its outside diameter and helical splines on its inside diameter. The outer carrier splines are in contact with straight splines in ring (10) and the inner splines are in contact with helical splines on fuel injection pump camshaft (5). As carrier (4) is forced to the left by oil pressure, is slides between the splines on ring (10) and the splines on camshaft (5). The helical splines on the camshaft and carrier cause the camshaft to turn in relation to timing gear (3). This action causes the fuel injection timing to be advanced.


Automatic Timing Advance Unit (Maximum Timing Advance)
(1) Spring. (2) Flyweights. (3) Timing gear. (4) Carrier. (5) Fuel injection pump camshaft. (6) Screw. (7) Setscrew. (8) Spring. (9) Bolt. (10) Ring. (11) Ring. (12) Spool. (13) Body.

As the engine speed increases, carrier (4), body (13), spool (12) and flyweights (2) continue to move toward the left until spool (12) makes contact with setscrew (7). Body (13) moves to the left until the oil ports close. Maximum fuel injection timing advance is adjusted and limited by setscrew (7).


Automatic Timing Advance Unit (Retard Timing Advance)
(1) Spring. (2) Flyweights. (3) Timing gear. (4) Carrier. (5) Fuel injection pump camshaft. (6) Screw. (7) Setscrew. (8) Spring. (9) Bolt. (10) Ring. (11) Ring. (12) Spool. (13) Body.

When the engine speed drops, the force of spring (8) may be greater than the force of flyweights (2). If the spring force is greater it will push spool (12) to the right. This will block the lubrication oil pressure in body (13) and allow the oil between the body and camshaft to drain out of the automatic timing advance unit. Spring (1) will move carrier, body, flyweight and spool to the right. This will cause fuel injection pump camshaft (5) to turn in relation to timing gear (3). The action causes the fuel injection timing to be retarded.

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.


Air Inlet And Exhaust System
(1) Exhaust manifold. (2) Inlet manifold. (8) Turbocharger.

The components of the air inlet and exhaust system control the quality and amount of air available for combustion. 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 air inlet (6) turbocharger compressor wheel (4). The rotation of the compressor wheel causes compression of the air and forces it through inlet manifold (2) to the inlet valves in the engine cylinder head. The inlet valves control the air flow into each engine cylinder.

There are two inlet and two exhaust valves for each cylinder. Make reference to Valve System Components. The inlet valves open when the piston moves down on the inlet stroke. Cooled compressed air from the inlet manifold is pulled into the cylinder. The inlet valves close and the piston starts to move up on the compression stroke. When the piston is near the top of the compression stroke fuel is injected into the cylinder. The fuel mixes with the air and combustion starts. The force of combustion pushes the piston down on the power stroke. When the piston moves up again it is on the exhaust stroke. The exhaust valves open and the exhaust gases are pushed through the exhaust port into exhaust manifold (1). After the piston makes the exhaust stroke the exhaust valves close and the cycle (inlet, compression, power, exhaust) starts again.

Exhaust gases from the exhaust manifold go into the turbine side of the turbocharger (8) and cause turbocharger turbine wheel (5) to turn. The turbine wheel is connected to the shaft that drives turbocharger compressor wheel (4). The exhaust gases then go out the exhaust outlet (7) and through exhaust system.

Aftercooler


Air Inlet System
(1) Aftercooler. (2) Air inlet pipe. (3) Coolant inlet. (4) Coolant outlet.

Some engines have an aftercooler (1) installed in place of the inlet manifold. The aftercooler has a coolant charged core assembly. Coolant from the water pump flows through coolant inlet (3) into the aftercooler. Coolant flows through the core assembly and out of the aftercooler through coolant outlet (4) into the rear of the cylinder block.

Inlet air from the compressor side of the turbocharger is forced into the aftercooler through air inlet pipe (2). The air passes over the core assembly which lowers the air temperature to approximately 93°C (199°F). The cooler air goes out the bottom of the aftercooler into the cylinder head. The advantage of the cooler air is greater combustion efficiency.

Turbocharger


Turbocharger
(1) Inlet manifold. (2) Exhaust manifold. (3) Turbocharger.

The turbocharger (3) is installed on the center section of the exhaust manifold (2). All the exhaust gases from the engine go through the turbocharger.


Turbocharger
(4) Air inlet. (5) Compressor housing. (6) Compressor wheel. (7) Bearing. (8) Oil inlet port. (9) Bearing. (10) Turbine housing. (11) Turbine wheel. (12) Exhaust outlet. (13) Oil outlet port. (14) Exhaust inlet.

The exhaust gases go into turbine housing (10) through exhaust inlet (14) and push the blades of turbine wheel (11). The turbine wheel is connected by a shaft to compressor wheel (6).

Clean air from the air cleaners is pulled through the compressor housing air inlet (4) by the rotation of compressor wheel (6). The action of the compressor wheel blades causes a compression of the inlet air. This compression gives the engine more power because it makes it possible for the engine to burn more air and fuel during combustion.

When the load on the engine increases, more fuel is injected into the cylinders. This makes more exhaust gases, and will cause the turbine and compressor wheels of the turbocharger to turn faster. As the compressor wheel turns faster, more air is forced into the engine. The increased flow of air gives the engine more power because it makes it possible for the engine to burn the additional fuel with greater efficiency.

Maximum rpm of the turbocharger is controlled by the fuel 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 fuel setting is higher than given in the TMI (Technical Marketing Information or Fuel Setting And Related Information Fiche (for the height above sea level at which the engine is operated), there can be damage to engine or turbocharger parts. Damage will result when increased heat and/or friction, due to the higher engine output, goes beyond the engine cooling and lubrication systems abilities.


The fuel setting 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 fuel and the high idle speed setting.

Bearings (7 and 9) for the turbocharger use engine oil under pressure for lubrication. The oil comes in through the oil inlet port (8) and goes through passages in the center section for lubrication of the bearings. Oil from the turbocharger goes out through the oil outlet port (13) in the bottom of the center section and goes back to the engine lubrication system.

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 (typical example)
(1) Inlet bridge. (2) Inlet rocker arm. (3) Push rod. (4) Rotocoil. (5) Valve springs (inner and outer). (6) Valve guide. (7) Inlet valves. (8) Lifter. (9) Camshaft.


Valve System Components
(1) Inlet bridge. (2) Inlet rocker arm. (7) Inlet valves. (10) Exhaust rocker arm. (11) Exhaust bridge. (12) Exhaust valves.

The inlet 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 lobes of the camshaft also turn and cause lifters (8) to go up and down. This movement makes push rods (3) move rocker arms (2 and 10). Movement of the rocker arms will make inlet and exhaust bridges (1 and 11) move up and down on dowels mounted in the cylinder head.

These bridges let one rocker arm open, or close, two valves (inlet or exhaust) at the same time. There are two inlet and two exhaust valves in each cylinder. Dependent on the application either one or two valve springs (5) for each valve hold the valves in the closed position when the lifters move down.

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


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.

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


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.

With the engine cold (starting conditions), oil comes from oil pan (6) through suction bell (9) to oil pump (7). When the oil is cold, an oil pressure difference in the bypass valves (installed in the oil filter housing) causes each valve 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 bypass valve (8) for the oil cooler and through bypass valve (5) for the oil filter to oil manifold (1) in the cylinder block and to supply line (2) for the turbocharger. Oil from the turbocharger goes back through oil return line (3) to the oil pan.

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

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 lubrication of the engine.

Oil Flow In The Engine


Engine Oil Flow Schematic
(1) Bracket for rocker arm. (2) Rocker arm shaft. (3) Oil passage (to lifters). (4) Valve lifter bore. (5) Oil supply rocker shaft bracket. (6) Rocker arm shaft. (7) Oil supply rocker shaft bracket. (8) Oil passage (to accessory drive). (9) Oil passage (to rocker shaft bracket). (10) Oil passage (to idler gear shaft). (11) Oil passage (to rocker shaft bracket). (12) Oil passage (to the fuel injection pump and governor). (13) Camshaft bearing. (14) Piston cooling jets. (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).

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 piston cooling jets (14) to make the pistons cooler. Oil goes through grooves in the bores for the front and rear camshaft bearings and then into oil 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 from lifter bores (4) through oil passage (11) to an oil passage in bracket (5) (next to cylinder No. 4) to supply pressure lubrication to rear rocker arm shaft (2). Oil is also sent from front main bearing bore through passage (9) to an oil passage in front bracket (7) for front rocker arm shaft (6). 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 oil passage (8) in the cylinder block, through passages in the timing gear housing and the accessory drive gear.

The idler gear gets oil from oil passage (10) 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 oil passage (12) 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.

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 (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.

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 water 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.

Coolant For Air Compressor


Coolant Flow In Air Compressor
(1) Outlet hose. (2) Air compressor. (3) Inlet hose.

The coolant for the air compressor (2) comes from the cylinder block through inlet hose (3) and into the air compressor. The coolant goes from the air compressor through outlet hose (1) back into the front of the cylinder head.

Electrical System

Engine Electrical System

The electrical system can have 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.

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

The low amperage circuit and the charging circuit are both connected through the ammeter. The starting circuit is not connected through the ammeter.

Grounding Practices

Proper grounding for the engine electrical systems is necessary for proper engine performance and reliability. Improper grounding will result in uncontrolled and unreliable electrical circuit paths which can result in damage to main bearings and crankshaft journal surfaces. Uncontrolled electrical circuit paths can also cause electrical noise which may degrade engine performance.

To insure proper functioning of the engine electrical systems, an engine-to-frame ground strap with a direct path to the battery must be used. This may be provided by way of a starting motor, a frame to starting motor ground, or a direct frame to engine ground.

Ground wires/straps should be combined at ground studs dedicated for ground use only. The engine alternator must be battery (-) grounded with a wire size adequate to handle full alternator charging current.


NOTICE

This engine may be equipped with a 12 or 24 volt starting system. Use only equal voltage for boost starting. The use of a welder or higher voltage will damage the electrical system.


Charging System Components

Alternator

The alternator is driven by 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.


NOTICE

Never operate the alternator without the battery in the circuit. Making or breaking an alternator connection with heavy load on the circuit can cause damage to the regulator.



Alternator Components
(1) Regulator. (2) Roller bearing. (3) Stator winding. (4) Ball bearing. (5) Rectifier bridge. (6) Field winding. (7) Rotor assembly. (8) Fan.

Starting System Components

Solenoid


Typical Solenoid Schematic

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

a. Closes the high current starting motor circuit with a low current start switch circuit.
b. Engages the starting motor pinion with the ring gear.

The solenoid switch is made of an electromagnet (one to 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 through 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 starting motor begins to turn the flywheel of the engine.

When the start switch is opened, current no longer flows through 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 through the hold-in winding, and the rest flows through the pull-in windings to the motor terminal, then through the motor to ground. When the solenoid is fully activated (connection across battery and motor terminal is complete), current is shut off through 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 starting motor pinion to engage it with the ring gear on the flywheel of the engine. The starting motor 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 starting motor 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.

Basic Block

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 from a seal between the liner and the cylinder block.

Pistons, Rings And Connecting Rods

The cast aluminum one piece 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 piston has a full skirt and uses a special shape (cardioid design) of the top surface to help combustion efficiency.

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.

The two piece pistons consist of an alloy steel crown connected to an aluminum skirt by the piston pin. Piston cooling jets in the cylinder block spray oil to the underside of the piston crown to cool the piston. All three rings are located in grooves in the piston crown. Holes in the oil control (lower) ring groove allow oil to return to the crankcase.

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. Two bolts hold the rod cap to the rod. This design keeps the rod width to a minimum, so that the rod can be removed through the cylinder.

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.

There are special design seals and wear sleeves used at both ends of the crankshaft. The seal for the front is different than the seal for the rear.

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 inlet) for each cylinder.

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.

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