Systems Operation

Usage:

Introduction

NOTE: For Specifications with illustrations, make reference to Specifications For 3516 Generator Set Engines, SENR5132. If the Specifications in SENR5132 are not the same as in the Systems Operation, Testing And Adjusting, look at the printing date on the back cover of each book. Use the Specifications given in the book with the latest date.

Engine Design

Cylinder And Valve Location

Number And Arrangement Of Cylinders ... 60° V-16

Valves Per Cylinder ... 4

Displacement ... 69.1 liter (4210 cu in)

Bore ... 170 mm (6.7 in)

Stroke ... 190 mm (7.5 in)

Compression Ratio ... 13.5:1

Type Of Combustion ... Direct Injection

Direction Of Crankshaft Rotation (as viewed from flywheel end) ... Counterclockwise

Firing Order (Injection Sequence) ... 1-2-5-6-3-4-9-10-15-16-11-12-13-14-7-8

Valve Lash Setting

Intake ... 0.38 mm (.015 in)

Exhaust ... 0.76 mm (.030 in)

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

Fuel System

General

Fuel Flow Schematic
(1) Fuel manifolds. (2) Fuel filter. (3) Fuel priming pump. (4) Fuel injectors. (5) Pressure regulating valve. (6) Fuel return to tank. (7) Primary fuel filter. (8) Fuel transfer pump. (9) Fuel line to filter (from transfer pump). (10) Fuel supply line from primary fuel filter. (11) Fuel line to priming pump (from transfer pump).

Fuel transfer pump (8) is located on the right side of the engine. The lower shaft of the engine oil pump drives the gear type transfer pump. Fuel from the supply tank is pulled through primary fuel filter (7) by the fuel transfer pump (8) and sent to fuel filter (2).

Fuel transfer pump (8) has a check valve and a bypass valve. The check valve is in the pump head assembly located behind where line (9) is connected. The check valve prevents fuel flow back through the transfer pump when fuel priming pump (3) is used. The bypass valve is located behind a cap (plug) in the drive end of the pump. The bypass valve limits the maximum pressure of the fuel. It will open the outlet side of the pump to the pump inlet if the fuel pressure exceeds 860 kPa (125 psi). This helps prevent damage to fuel system components caused by too much pressure.

Right Side Of Engine
(8) Fuel transfer pump. (9) Fuel line to filter. (10) Fuel supply line from primary fuel filter. (11) Fuel line to priming pump.

Right Front Of Engine
(1) Fuel manifolds. (2) Fuel filter.

The transfer pump pushes fuel through fuel filter (2) on the front of engine to fuel manifolds (1). Each fuel manifold has two sections. The fuel flows through the top section of the manifold to inlet fuel line (13) connected to the right side of each cylinder head. Filter screens are located in the ports of the unit injector. A drilled passage (14) in cylinder head (15) takes fuel to a circular (shape of a circle) chamber around the injector. The chamber is made by O-rings on the outside diameter of injector (4) and the injector bore in the cylinder head.

Cylinder Heads
(4) Injector. (12) Outlet fuel line. (13) Inlet fuel line.

Only part of the fuel in the chamber is used for injection. Approximately three to five times as much fuel as needed for normal combustion flows through the chamber to a drilled passage in the left side of the cylinder head. This passage is connected by outlet fuel line (12) to the bottom section of the fuel manifold. This constant flow of fuel around the injector helps to cool them.

Fuel Flow Through Injector
(4) Injector. (12) Outlet fuel line. (13) Inlet fuel line. (14) Drilled passage. (15) Cylinder head. (16) Cylinder.

The fuel flows back through the bottom section of each fuel manifold to pressure regulating valve (5), on the front of the right fuel manifold. The fuel flows through this valve and then back to the tank.

Check each engine installation for an excess fuel flow based on fuel consumed (used for combustion). Minimum flow is three times the amount of fuel consumed. Excess fuel is then returned to the fuel tank, not back to the pump inlet. This will make sure that any air in the system will be removed before the fuel is sent back to the injectors.

Pressure regulating valve (5) has a spring and plunger arrangement between the bottom section of the fuel manifolds and the line that returns fuel to the tank. The valve keeps the pressure of the fuel at 415 to 450 kPa (60 to 65 psi).

Fuel Injection Control Linkage

Fuel Injector Control Linkage
(1) Injector. (2) Control shaft (left side). (3) Bellcrank. (4) Control rod. (5) Rack. (6) Lever. (7) Governor shaft. (8) Control shaft (right side). (9) Cross shaft.

A fuel injector (1) is located in each cylinder head. The position of rack (5) controls the amount of fuel injected into the cylinder. Pull the rack out of the injector for more fuel, push it in for less fuel.

Rack position is changed by bellcrank (3). The bellcrank is moved by control rod (4). The control rods have an adjustment screw on the top. The adjustment screw is used to synchronize the injectors. The control rods are spring loaded. If the rack of one injector sticks (will not move), it will still be possible for the governor to control the other racks so the engine can be shutdown. Each control rod on the right side of the engine is connected by a lever (6) to control shaft (8).

When the rotation of governor shaft (7) is clockwise, as seen from in front of the engine, the action of the governor linkage moves control shaft (8) counterclockwise (fuel "ON" direction).

Right control shaft (8) and left control shaft (2) are connected by cross shaft (9). The linkage between the injectors on the left side of the engine and control shaft (2) is similar to the linkage on the right side.

Should the linkage become disconnected from the governor, the weight of the control linkage will move the fuel injector racks to the fuel "SHUTOFF" position, and the engine will stop.

Fuel Injector

Fuel Injector Operation
(1) Screw. (2) Rocker arm. (3) Clamp. (4) Control rod. (5) Rack. (6) Drilled passage. (7) Upper port. (8) Lower port. (9) Plunger. (10) Barrel. (11) Fuel passage. (12) Needle valve. (13) Lifter assembly. (14) Camshaft. (15) Piston.

The injector is held in position by clamp (3). Fuel is injected when rocker arm (2) pushes the top of the injector down. The movement of the rocker arm is controlled by the camshaft through lifter assembly (13) and push rod (4). The amount of fuel injected is controlled by rack (5). Movement of the rack causes rotation of a gear fastened to plunger (9). Rotation of the plunger changes the effective stroke (that part of the stroke during which fuel is actually injected) of the plunger.

Injection timing is a product of two factors; the angular location of camshaft (14) and the location of plunger (9). The angular location of the camshaft is controlled by the camshaft drive gears at the rear of the engine. The location of the plunger can be adjusted with screw (1).

Fuel Injection Cycle

When the plunger is at the top of its stroke, fuel flows from the fuel supply chamber, around the injector and through both the lower and upper ports of barrel (10). As plunger (9) is moved down by rocker arm (2), fuel is pushed back into the supply chamber through lower port (8). It also can go through a drilled passage (6) in the center of the plunger, around the relief groove (scroll area), and out through upper port (7) of the barrel. As the lower port (8) is closed by the bottom of plunger (9), fuel can still flow through upper port (7) until it is closed by the upper edge of the relief groove on plunger (9). At this point, injection starts and the effective stroke of the plunger begins.

During the effective stroke, fuel is injected into the cylinder until the movement of plunger (9) downward allows the scroll (helix) to open the lower port and release the fuel pressure. The amount of fuel injected during the effective stroke is determined by the position of the scroll in relation to the lower port.

Fuel then goes through center passage (6) of the plunger and lower port (8) during the remainder of the downstroke. This sudden release of very high pressure as the lower port is opened causes the fuel to hit the spill deflector (outside of both ports) with a high force. The spill deflector gives protection to the injector housing from erosion (wear) because of the force of the released fuel. On the return (up) stroke, the injector barrel is filled with fuel again from the fuel supply chamber.

The plunger can be turned by rack (5) at the same time it is moved up and down by rocker arm (2). The upper part of the plunger has a flat side that fits through the gear which is engaged with the rack. The plunger slides up and down in the gear, and when the rack moves, the gear and plunger rotate together. This rotation of plunger (9) controls the fuel output of the injector. Rotation of the plunger changes the relation of the plunger scroll to the lower port in the barrel, and increases or decreases the length of the effective stroke for injection. Since the plunger scroll can set the amount of fuel per injection stroke, the fuel rate to the engine can be controlled in relation to different engine loads.

When rack (5) is moved all the way in against the injector body, no injection takes place during the downstroke of the plunger. This is the fuel "shutoff" position. When the rack is moved out a small distance, fuel injection begins. As the rack continues to move out, the amount of fuel injected into the cylinder is increased until maximum fuel position is reached.

During the fuel injection stroke, fuel passes from the barrel chamber through a valve assembly. The valve assembly has a spring-loaded needle valve (12) and fuel flows through fuel passages (11) around the needle valve to the valve chamber. Here the fuel pressure lifts the needle valve off its seat and the fuel can now flow through the orifices in the tip into the combustion chamber.

If needle valve (12) is held open by small combustion debris for a moment between injection cycles, combustion gases could come into the injector and cause damage. A flat check valve is used above the needle valve to keep these high pressure combustion gases out of the injector. The injector operates with the flat check valve until the foreign particle has been washed out through the orifices by the fuel, and normal operation again takes place.

The tip of the injector extends a short distance below the cylinder head into the combustion chamber. It has several small orifices evenly spaced around the outside diameter to spray fuel into the combustion chamber. The top surface of the piston (15) is designed with a shaped crater that causes the air to swirl (go into rotation). As the fuel is sprayed into the swirling air, the mixture is improved for more complete combustion.

Air Inlet And Exhaust System

The components of the air inlet and exhaust system control the quality and amount of air available for combustion. There is one turbocharger and an exhaust manifold on each side of the engine. There is one aftercooler located between the cylinder heads in the center of the engine. The inlet manifold is a series of elbows that connect the aftercooler chamber to the inlet ports (passages) of the cylinder heads. Two camshafts, one in each side of the block, control the movement of the valve system components.

Air Inlet And Exhaust System
(1) Exhaust manifold. (2) Aftercooler. (3) Engine cylinder. (4) Air inlet. (5) Turbocharger compressor wheel. (6) Turbocharger turbine wheel. (7) Exhaust outlet.

Air flow is the same on both sides of the engine. Clean inlet air is pulled through air inlet (4) into turbocharger compressor by compressor wheel (5). The rotation of the compressor wheel causes compression of the air and forces it through a tube to aftercooler (2). The aftercooler lowers the temperature of the compressed air before it goes into the inlet chambers in each cylinder head. This cooled, compressed air fills the inlet chambers in the cylinder heads. Air flow from the inlet port into the cylinder is controlled by the intake valves.

There are two intake and two exhaust valves for each cylinder. Make reference to Valve System Components. The intake valves open when the piston moves down on the inlet stroke. Cooled, compressed air from the inlet chamber is pulled into the cylinder.

The intake 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 and cause turbine wheel (6) to turn. The turbine wheel is connected to the shaft that drives compressor wheel (5). The exhaust gases then go out the exhaust outlet (7) through exhaust elbows.

Aftercooler

The aftercooler is located at the center of the vee, and has a coolant charged core assembly. Coolant from water pump (2) flows through pipe (1) into the aftercooler. It then flows through the core assembly (assemblies) and back out of the aftercooler through a different pipe into the rear of the cylinder block.

There is a connector (tube) that connects the bottom rear of each core assembly to the cylinder block. This is used to drain the aftercooler when the coolant is drained from the engine.

Inlet air from the compressor side of the turbochargers flows into the aftercooler through pipes. The air then passes through the fins of the core assembly (assemblies) which lowers the temperature. The cooler air goes out the bottom of the aftercooler into the air chamber then up through the elbows to the inlet ports (passages) in the cylinder heads.

Right Front Of Engine
(1) Pipe. (2) Water pump.

Aftercooler Air Chamber Drain
(3) Drain plug.

One drain plug is located between the No. 1 and 3 cylinder heads and another plug is located between the last two cylinder heads on the left side of the engine. These plugs can be removed to check for water or coolant in the aftercooler air chamber.

Turbochargers

Two turbochargers (1) are used on the rear of the engine. The turbine side of each turbocharger is connected to its respective exhaust manifold. The compressor side of each turbocharger is connected by pipes to the aftercooler housing. The turbocharger is supported by the central exhaust elbow.

Turbochargers
(1) Turbocharger. (2) Oil drain line. (3) Oil supply line.

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

The exhaust gases go into the exhaust inlet of the turbine housing and push the blades of turbine wheel (11). This causes the turbine wheel and compressor wheel to turn at speeds up to 60,000 rpm.

Clear air from the air cleaners is pulled through the compressor housing air inlet (10) by rotation of compressor wheel (4). The action of the compressor wheel blades compresses the inlet air and increases density or flow. This increased flow gives the engine the ability to burn additional fuel and therefore increase its power output.

Maximum rpm of the turbocharger is controlled by the fuel setting, the height above sea level at which the engine is operated, and the inlet restriction (air cleaner blockage).

Show/hide table

NOTICE

If the fuel setting is higher than given in the 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. A mechanic that has the proper training is the only one to make the adjustment of fuel setting and high idle rpm setting.

The bearings (5 and 7) in the turbocharger use engine oil under pressure for lubrication. The oil is sent through oil inlet port (6) then goes through passages in the center section for lubrication of the bearings. Then the oil goes out oil outlet port (11) at the bottom and back to the flywheel housing through the drain line.

Valve System Components

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

The crankshaft gear drives the camshaft gears through idlers. Both camshafts must be timed to the crankshaft to get the correct relation between piston and valve movement.

Valve System Components
(1) Rocker arm. (2) Bridge. (3) Rotocoil. (4) Valve spring. (5) Push rod. (6) Lifter.

The camshafts have three cam lobes for each cylinder. Two lobes operate the valves and one operates the fuel injector.

As each camshaft turns the lobes on the camshaft cause lifters (6) to go up and down. This movement makes push rods (5) move the rocker arms (1). Movement of the rocker arms makes the bridges (2) move up and down on dowels in the cylinder head. The bridges let one rocker arm open and close two valves (intake or exhaust). There are two intake and two exhaust valves for each cylinder.

Rotocoils (3) cause the valves to turn while the engine is running. The rotation of the valves keeps the deposit of carbon on the valves to a minimum and gives the valves longer service life.

Valve springs (4) cause the valves to close when the lifters move down.

Lubrication System

Main Oil Pump And Lubrication System Schematic
(1) Main oil gallery. (2) Left camshaft oil gallery. (3) Piston cooling jet oil gallery. (4) Piston cooling jet oil gallery. (5) Right camshaft oil gallery. (6) Turbocharger oil supply. (7) Sequence valve. (8) Sequence valve. (9) Adapter. (10) Oil filter bypass valve. (11) Oil cooler. (12) Oil cooler bypass valve. (13) Oil pump relief valve. (14) Engine oil pump. (15) Elbow. (16) Suction bell. (17) Oil filter housing.

This system uses an oil pump (14) with three pump gears that are driven by the front gear train. Oil is pulled from the pan through suction bell (16) and elbow (15) by the oil pump. The suction bell has a screen to clean the oil.

There is a relief valve (13) in the oil pump. Relief valve (13) controls the pressure of the oil from the oil pump. The oil pump can put more oil into the system than is needed. When there is more oil than needed, the oil pressure goes up and the relief valve will open. This lets the oil that is not needed go back to the inlet oil passage of the oil pump.

The oil pump pushes oil through oil cooler (11) and the oil filters to oil galleries (1 and 2) in the block. The tube type oil cooler lowers the temperature of the oil before the oil is sent on to the filters.

Bypass valve (12) lets oil flow directly to the filters if the oil cooler becomes plugged or if the oil becomes thick enough (cold start) to increase the oil pressure differential (cooler inlet to outlet) by an amount of 180 ± 20 kPa (26 ± 3 psi).

Cartridge type filters are located in oil filter housing (17) at the front of the engine. A single bypass valve is located in the oil filter housing.

Clean oil from the filters goes into the block through adapter (9). Part of the oil goes to left camshaft oil gallery (2), and the remainder goes to main oil gallery (1).

The camshaft oil galleries (2 and 5) are connected to each camshaft bearing by a drilled hole. The oil goes around each camshaft journal, through the cylinder head and rocker arm housing, to the rocker arm shaft. A drilled hole connects the bores for the valve lifters to the oil hole for the rocker arm shaft. The valve lifters get lubrication each time they go to the top of their stroke.

Main oil gallery (1) is connected to the main bearings by drilled holes. Drilled holes in the crankshaft connect the main bearing oil supply to the rod bearings. Oil from the rear of the main oil gallery goes to the rear of right camshaft gallery (5).

Sequence valves (7 and 8) let oil from main oil gallery (1) go to piston cooling jet oil galleries (3 and 4). The sequence valves begin to open at approximately 130 kPa (19 psi). The sequence valves will not let oil into the piston cooling jet oil galleries until there is pressure in the main oil gallery. This decreases the amount of time necessary for pressure build-up when the engine is started. It also helps hold pressure at idle speed.

Piston Cooling And Lubrication
(18) Cooling jet.

There is a piston cooling jet (18) below each piston. Each cooling jet has two openings. One opening is in the direction of a passage in the bottom of the piston. This passage takes oil to a manifold behind the ring band of the piston. A slot (groove) is in the side of both piston pin bores to connect them with the manifold behind the ring band. The other opening is in the direction of the center of the piston. This helps cool the piston and gives lubrication to the piston pin.

Turbochargers
(6) Oil supply lines. (19) Oil drain lines.

Oil lines (6) send oil from the rear adapter to the turbochargers. The turbocharger drain lines (19) are connected to the flywheel housing on each side of the engine.

Oil is sent to the front and rear gear groups through drilled passages in the front and rear housings and cylinder block faces. These passages are connected to camshaft oil galleries (2 and 5).

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

Right Front Side Of Engine (Typical Example)
(10) Oil filter bypass valve. (17) Oil filter housing. (19) Oil line to filter housing.

Left Front Of Engine
(9) Elbow. (10) Oil filter bypass valve. (17) Oil filter housing. (20) Oil outlet line from oil filter housing. (23) Filter oil supply from oil pump.

Cooling System

Schematic Of Cooling System
(1) Water pump. (2) Tube (to aftercooler). (3) Oil cooler. (4) Block. (5) Cylinder head. (6) Water manifold. (7) Aftercooler. (8) Regulator housing. (9) Tube (to radiator or heat exchanger). (10) Bypass tube.

Coolant goes in water pump (1) through an elbow that connects to the radiator or heat exchanger. The coolant flow is divided at the outlet of the water pump. Part of the coolant flow is sent to the aftercooler through tube (2). The remainder of the coolant goes through the oil cooler (3).

NOTE: There is one opening on the pump outlet so that a remote pump can be connected to the system. The remote pump can be used if there is a failure of the pump on the engine.

Coolant sent to the aftercooler goes through the aftercooler core and is sent by an elbow into a passage in the block near the center of the vee at the rear of the block. The coolant sent to the oil cooler goes through the oil cooler and flows into the water jacket of the block at the right rear cylinder. The cooler coolant mixes with the hotter coolant and goes to both sides of the block through distribution manifolds connected to the water jacket of all the cylinders. The main distribution manifold is located just above the main bearing oil gallery.

The coolant flows up through the water jackets and around the cylinder liners from the bottom to the top. Near the top of the cylinder liners, where the temperature is the hottest, the water jacket is made smaller. This shelf (smaller area) causes the coolant to flow faster for better liner cooling. Coolant from the top of the liners goes into the cylinder head which sends the coolant around the parts where the temperature is the hottest. Coolant then goes to the top of the cylinder head and out through an elbow, one at each cylinder head, into water manifold (6) at each bank of cylinders. Coolant goes through the manifold to the temperature regulator (thermostat) housing.

Regulator housing (8) has an upper and lower flow section, and uses four temperature regulators. The sensing bulbs of the four temperature regulators are in the coolant in the lower section of the housing. Before the regulators open, cold coolant is sent through the bypass line back to the inlet of the water pump. As the temperature of the coolant increases enough to make the regulators start to open, coolant flow in the bypass line is restricted and some coolant is sent through the outlets to the radiator or heat exchanger. Because the regulators are in the coolant outlet of the engine, it is known as a controlled outlet system.

Total system capacity will depend on the amount of cylinder block coolant as well as the amount of coolant in the radiator or heat exchanger. Use a coolant a mixture of 50 percent pure water, 50 percent permanent antifreeze with a three to six percent concentration of corrosion inhibitor.

Basic Block

Cylinder Block, Liners And Heads

The cylinders in the left side of the block make an angle of 60 degrees with the cylinders in the right side of the block. The main bearing caps are fastened to the block with four bolts per cap.

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

The engine has a separate cylinder head for each cylinder. Four valves (two intake and two exhaust), controlled by a push rod valve system, are used for each cylinder. Valve guides without shoulders are pressed into the cylinder heads. The opening for the fuel injector is located between the four valves. A third lobe on the camshaft moves the push rod system that operates the fuel injector. Fuel is injected directly into the cylinder.

There is an aluminum spacer plate between each cylinder head and the block. Coolant goes out of the block through the spacer plate and into the head through eight openings in each cylinder head face. Water seals are used in each opening to prevent coolant leakage. Gaskets seal the oil drain passages between the head, spacer plate and block.

Left Side Of Engine (Typical Example)
(1) Covers for camshafts and fuel control linkage inspection. (2) Covers for crankshaft main and rod bearing inspection.

Covers (1) allow access to the camshafts, valve lifters and fuel control shaft.

Covers (2) allow access to the crankshaft connecting rods, main bearings and piston cooling jets. With covers removed, all the openings can be used for inspection and service.

Pistons, Rings And Connecting Rods

The aluminum pistons have an iron band for the top two rings. This helps reduce wear on the compression ring grooves. A chamber is cast into the piston just behind the top ring grooves. Oil from the piston cooling jets flows through this chamber to cool the piston and improve ring life. The pistons have three rings; two compression rings and one oil ring. All the rings are located above the piston pin bore. The oil ring is a standard (conventional) type. Oil returns to the crankcase through holes in the oil ring groove. The top two rings are the KEYSTONE type, which are tapered. The action of the ring in the piston groove, which is also tapered, helps prevent seizure of the rings caused by too much carbon deposit.

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. Four bolts set at a small angle hold the rod cap to the rod. This design keeps the rod width to a minimum, so that a larger rod bearing can be used and the rod can still be removed through the liner.

Crankshaft

The crankshaft changes the combustion forces in the cylinder into usable rotating torque which powers the machine. A vibration damper of the fluid type is used at the front of the crankshaft to reduce torsional vibrations (twist on the crankshaft) that can cause damage to the engine.

The crankshaft is symmetrical. This makes it possible to turn the crankshaft end for end when opposite engine rotation is desired.

The crankshaft drives a group of gears on the front and rear of the engine. The gear group on the front of the engine drives the oil pump, (jacket water) water pump, fuel transfer pump, governor and two accessory drives.

The rear gear group, also driven by the crankshaft, drives the camshafts.

Seals and wear sleeves are used at both ends of the crankshaft for easy replacement and a reduction of maintenance cost. Pressure oil is supplied to all main bearings through drilled holes in the webs of the cylinder block. The oil then flows through drilled holes in the crankshaft to provide oil to the connecting rod bearings. The crankshaft is held in place by nine main bearings. A thrust plate at either side of the center main bearing controls the end play of the crankshaft.

Camshafts

The engine has a camshaft group for each side of the engine. Nine bearings support each camshaft group. Two camshafts per side that are doweled and bolted together make up the camshaft groups. The camshaft groups are driven by the gears at the rear of the engine.

As the camshaft turns, each lobe moves a lifter assembly. There are three lifter assemblies for each cylinder. Each outside lifter assembly moves a push rod and two valves (either intake or exhaust). The center lifter assembly moves a push rod that operates the fuel injector. The camshafts must be in time with the crankshaft. The relation of the cam lobes to the crankshaft position cause the valves and fuel injectors in each cylinder to operate at the correct time.

Air Starting System

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

Air Starting System
(1) Air starting motor. (2) Relay valve. (3) Oiler.

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

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

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

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

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

Typical Air Start Installation
(4) Air start control valve.

The air from the supply goes to relay valve (2). The starter control valve (4) is connected to the line before the relay valve (2). The flow of air is stopped by the relay valve (2) until starter control valve (4) is activated.

Air Starting Motor
(5) Air inlet. (6) Vanes. (7) Rotor. (8) Pinion. (9) Gears. (10) Piston. (11) Piston spring.

The air from starter control valve (4) goes to piston (10) behind pinion (8) for the starter. The air pressure on piston (10) puts spring (11) in compression and puts pinion (8) in engagement with the flywheel gear. When the pinion is in engagement, air can go out through another line to relay valve (2). The air activates relay valve (2) which opens the supply line to the air starting motor.

The flow of air goes through the oiler (3) where it picks up lubrication oil for the air starting motor.

The air with lubrication oil goes into the air motor. The pressure of the air pushes against vanes (6) in rotor (7). This turns the rotor which is connected by gears (9) and a drive shaft to starter pinion (8) which turns the engine flywheel.

When the engine starts running the flywheel will start to turn faster than starter pinion (8). Pinion (8) retracts under this condition. This prevents damage to the motor, pinion (8) or flywheel gear.

When starter control valve (4) is released, the air pressure and flow to piston (10) behind starter pinion (8) is stopped, piston spring (11) retracts pinion (8). Relay valve (2) stops the flow of air to the air starting motor.

Electrical System

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

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

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

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

Charging System Components

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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

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

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) to the alternator. The output voltage from the alternator will now supply the needs of the battery and the other components in the electrical system. No adjustment can be made to change the rate of charge on these alternator regulators.

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

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

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 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 alternator is driven by belts from the crankshaft pulley. The alternators are brushless and contain an internally mounted, solid state voltage regulator.

Alternator Components
(1) Fan. (2) Front frame assembly. (3) Stator assembly. (4) Rotor assembly. (5) Field winding (coil) assembly. (6) Regulator assembly. (7) Condenser (suppression capacitor). (8) Rectifier assembly. (9) Rear frame assembly.

The major components of the alternator are stator assembly (3), rectifier assembly (8), field winding (5), rotor assembly (4), regulator assembly (6) and condenser (suppression capacitor) (7).

Stator assembly (3) consists of a stator core and coils. As the rotor turns, its varying magnetic field causes the stator coil to produce three-phase alternating current (AC).

Rectifier assembly (8) contains three positive diodes and three negative diodes to form the full wave rectifier which is connected to the stator assembly. The 50A alternator has four positive and four negative diodes.

Rectifier assembly (8) changes three-phase AC to DC and provides excitation current through three exciter diodes.

Field winding (5) is a stationary coil assembly that provides the magnetic field for the rotor assembly. Rotor assembly (4) provides the north and south poles which cut the magnetic field between the rotor field winding and the stator assembly. The north and south poles are separated by non-magnetic ring (12). Regulator assembly (6) controls alternator output. It is mounted inside the rear frame assembly.

Condenser (7) serves as a suppression capacitor. It protects the alternator diodes from voltage spikes. It also suppresses radio and electronic interference. Condenser (7) also contains a resistor which is in series with the condenser. The condenser is mounted in the rear frame assembly on top of the regulator assembly.

Starting System Components

Starter Solenoid

A solenoid is an electromagnetic 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.

Typical Solenoid Schematic

The solenoid has windings (one or two sets) 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 windings, and the rest flows through the pull-in windings to 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 running.

Starting Motor Cross Section (Typical Illustration)
(1) Field. (2) Solenoid. (3) Clutch. (4) Pinion. (5) Commutator. (6) Brush assembly. (7) Armature.

The starting motor has a solenoid. When the start switch is activated, electricity will flow through the windings of the solenoid. The solenoid core will now move to push the starter pinion, by a mechanical linkage to engage 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, when it starts to run, can not turn the starting motor too fast. When the start switch is released, the starter pinion will move away from the flywheel ring gear.

Other Components

Circuit Breaker

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

A heat activated metal disc with a contact point completes 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 metal disc which opens the contacts and breaks the circuit. A circuit breaker that is open can be reset after it cools. Push the reset button to close the contacts and reset the circuit breaker.

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NOTICE

Find and correct the problem that causes the circuit breaker to open. This will help prevent damage to the circuit components from too much current.

Circuit Breaker Schematic
(1) Reset button. (2) Disc in open position. (3) Contacts. (4) Disc. (5) Battery circuit terminals.

Magnetic Pickup

Schematic of Magnetic Pickup
(1) Magnetic lines of force. (2) Wire coils. (3) Gap. (4) Pole piece. (5) Flywheel ring gear.

The magnetic pickup is a single pole, permanent magnet generator made of wire coils (2) around a permanent magnet pole piece (4). As the teeth of the flywheel ring gear (5) cut through the magnetic lines of force (1) around the pickup, an AC voltage is generated. The frequency of this voltage is directly proportional to engine speed.

Magnetic Switch

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

Water Temperature Contactor Switch

The contactor switch for water temperature is installed in the regulator housing. No adjustment to the temperature range of the contactor can be made. The element feels the temperature of the coolant and then operates the micro switch in the contactor when the coolant temperature is too high. The element must be in contact with the coolant to operate correctly. If the reason for the engine being too hot is caused by low coolant level or no coolant, the contactor switch will not operate.

The contactor switch is normally connected to the electric shutoff system to stop the engine. The switch can also be connected to an alarm system. When the temperature of the coolant lowers again to the operating range, the contactor switch opens automatically.