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 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 plunger (5) the fuel nozzle closes and spring (13) closes check valve (2) as the pressure above plunger (5) drops below 690 kPa (100 psi). At the same time 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: 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 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 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 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 fuel with high pressure to the fuel injection nozzle where the fuel is made into a fine spray for good combustion.

Fuel Injection Nozzle
(1) Carbon dam. (2) Seal. (3) Passage. (4) Filter screen. (5) Inlet passage. (6) Orifice. (7) Valve. (8) Diameter. (9) Spring.

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

Fuel with high pressure 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).

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.

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.

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 from cylinder block. (5) Oil drain 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 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) Over fueling spring. (10) Load stop bar. (11) Stop bar. (12) Riser. (13) Spring seat. (14) Torque rise setting screw. (15) Stop bolt. (16) Torque spring. (17) Fuel setting screw. (18) 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 (12) 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 engine is cranked to start and the governor is at low idle position, over fueling spring (9) moves the riser forward and gives an extra amount of fuel to the engine. When the engine has started and begins to run, the flyweight force becomes greater than the force of the over fueling spring. The riser moves to the rear and reduces the amount of fuel to the low idle requirement of the engine.

When the governor control lever is moved to the high idle position, governor spring (1) is put in compression and pushes riser (12) 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 (12) forward and increases the amount of fuel to the engine. As the load is increased more, governor spring (1) pushes riser (12) farther forward. Spring seat (13) also pushes on stop bolt (15). On the opposite end of stop bolt (15) is stop collar (18) which has fuel setting screw (17) and torque rise setting screw (14). Torque rise setting screw (14) controls the maximum amount of fuel rack travel. As stop bolt (15) moves forward fuel setting screw (17) moves forward to make full contact with torque spring (16) at the full load speed of the engine. The adjustment of fuel setting screw (17) controls the horsepower of the engine at full load speed. Torque spring (16) 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 (12) farther forward. As stop bolt (15) moves forward, fuel setting screw (17) bends torque spring (16) and fuel rack (6) can move farther in the FUEL ON direction.

This movement is stopped when torque rise setting screw (14) contacts stop bar (11). This is the maximum fuel setting position. The adjustment of torque rise setting screw (14) 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 so 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

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).

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.

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.

Fuel Ratio Control - (For Use With Earlier Engines)

Fuel Ratio Control
(Engine Started) (Typical Example) (1) Inlet air chamber. (2) Diaphragm assembly. (3) Internal valve. (4) Oil drain passage. (5) Oil inlet. (6) Stem. (7) Spring. (8) Piston. (9) Oil passage. (10) Oil chamber. (11) Lever.

The fuel ratio control limits the amount of fuel to the cylinders during an increase of engine speed (acceleration) to reduce exhaust smoke. Properly adjusted it also minimizes the amount of soot in the engine.

Stem (6) moves lever (11) which will restrict the movement of the fuel rack in the FUEL ON direction only.

With the engine stopped, there is no oil pressure and stem (6) is in the fully extended position as in the (Engine Started) illustration. The movement of the fuel rack and lever (11) is not restricted by stem (6). This gives maximum fuel to the engine for easier starts.

After the engine is started, engine oil flows through oil inlet (5) into pressure oil chamber (10). From oil chamber (10) oil flows through oil passage (9) into internal valve (3) and out oil drain passages in stem (6).

Stem (6) will not move until inlet manifold pressure increases enough to move internal valve (3). A line connects the inlet manifold with inlet air chamber (1) of the fuel ratio control.

Fuel Ratio Control (Control Activated) (Typical Example)
(1) Inlet air chamber. (2) Diaphragm assembly. (3) Internal valve. (4) Oil drain passage. (5) Oil inlet. (6) Stem. (7) Spring. (8) Piston. (9) Oil passage. (10) Oil chamber. (11) Lever.

When the manifold pressure increases, it causes diaphragm assembly (2) to move towards the right. This also causes internal valve (3) to move to the right. When internal valve (3) moves to the right, it closes oil passage (9).

When oil passage (9) is closed, oil pressure increases in oil chamber (10). Oil pressure moves piston (8) and stem (6) to the left and into the operating position. The fuel ratio control will remain in the operating position until the engine is shut off or the inlet manifold pressure increases with the addition of more load on the engine.

Fuel Ratio Control (Engine Acceleration) (Typical Example)
(1) Inlet air chamber. (2) Diaphragm assembly. (3) Internal valve. (4) Oil drain passage. (5) Oil inlet. (6) Stem. (7) Spring. (8) Piston. (9) Oil passage. (10) Oil chamber. (11) Lever.

When the governor control is moved to increase fuel to the engine, stem (6) limits the movement of lever (11) in the FUEL ON direction. The oil in oil chamber (10) acts as a restriction to the movement of stem (6) until inlet air pressure increases.

As the inlet air pressure increases, diaphragm assembly (2) and internal valve (3) move to the right. The internal valve opens oil passage (9), and oil in oil chamber (10) goes to oil drain passage (4). With the oil pressure reduced behind piston (8), spring (7) moves the piston and stem (6) to the right. Piston (8) and stem (6) will move until oil passage (9) is closed by internal valve (3). Lever (11) can now move to let the fuel rack go to the full fuel position. The fuel ratio control is designed to restrict the fuel until the air pressure in the inlet manifold is high enough for complete combustion. It prevents large amounts of exhaust smoke caused by an air-fuel mixture with too much fuel.

Fuel Ratio Control (Sealed Unit) - For Use With Later Engines

Fuel Ratio Control (Sealed Unit)
(1) Governor. (2) Fuel ratio control.

The fuel ratio control (FRC) restricts the amount of fuel to the combustion chambers until sufficient boost has been achieved to ensure clean combustion on turbocharged engines. Unlike the earlier FRC designs, this control is a sealed unit. Individual parts of the unit are not serviceable.

Earlier FRC designs required a static lever setting adjustment inside the governor housing. The sealed fuel ratio control is used with a lever assembly that is activated by oil pressure. No static lever setting is required with the sealed FRC.

At engine startup, the governor causes servo valve (12) and the fuel rack to move in the FUEL ON direction (to the left). [Refer to subject Governor in the Service Manual for operation of servo valve (12) and fuel rack.] As servo valve (12) moves left, it forces lever assembly (11) to rotate clockwise against the light tension of spring (14).

After engine startup, servo valve (12) travels right to an idle rack position. As the servo valve moves, spring (14) causes lever assembly (11) to rotate counterclockwise until a cross drilled hole in the sleeve of lever assembly (11) aligns with piston cavity ports in lever assembly (8). Engine lube oil, feeding from the governor housing into the center passage of shaft (10), now travels through a cross drilled hole in the shaft to enter a piston cavity in lever assembly (8). The pressure of the oil against the piston caused lever assembly (8) to slide sideways and compress spring (14). Tangs (13) of lever assemblies (8 & 11) are now overlapped, restricting clockwise rotation of lever assembly (11). With lever assembly (11) restricted, the FUEL ON travel of servo valve (12) is also restricted.

Fuel Ratio Control And Governor
(3) Port. (4) Chamber. (5) Diaphragm. (6) Retainer assembly. (7) Rod. (8) Lever assembly. (9) Springs. (10) Shaft. (11) Lever assembly. (12) Servo valve. (13) Tangs. (14) Spring.

During engine operation, any increase in intake manifold boost pressure is sent to chamber (4) through port (3). When boost is sufficient, diaphragm (5) forces retainer assembly (6) and rod (7) to the right. Lever assemblies (8 & 11) now rotate clockwise, allowing servo valve (12) to move left for increased fuel.

When boost pressure drops, spring (9) return retainer (6) and rod (7) to normal position. FUEL ON movement of the servo valve is again restricted until sufficient boost is achieved.

When the engine is shut off, oil pressure is released from the piston cavity of lever assembly (8). Spring (14) forces lever assembly (8) away from lever assembly (11). Lever assembly (11) is no longer restricted. The fuel ratio control is ready for the next engine startup.

NOTE: A variation of this design is used for engine applications where unrestricted rack travel is NOT desirable for startup. In those applications, spring (14) is removed and lever assembly (8) is modified so that lever tangs (13) are always overlapped. Servo valve and rack travel at startup are limited to the FRC setting.

Automatic Timing Advance Unit 7FB1-Up, 4MG1-4MG3599

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 cattier, 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.

Automatic Timing Advance Unit 4MG3600-Up, 5KJ1-Up, 3ZJ1-Up

Timing Advance Unit (Before Timing Advance Begins) (Typical Example)
(1) Screw. (2) Setscrew. (3) Spring. (4) Valve spool. (5) Flyweights. (6) Ring. (7) Gear. (8) Carrier. (9) Fuel injection pump camshaft. (10) Body assembly. (11) Bolt. (12) Ring.

The 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 used engine oil pressure to change the fuel injection timing. A flyweight assembly controls a double acting hydraulic servo. The double acting hydraulic servo, directs engine oil under pressure to either side of the drive carrier to advance or retard timing. The total timing advance range is 12 crankshaft degrees.

The timing advance unit is connected to the fuel injection pump camshaft. Bolts (11) pull rings (6 and 12) together to hold gear (7). Carrier (8) has two splines. The outer straight splines are in contact with the straight splines of ring (6) and the inner helical splines are in contact with the helical splines on fuel injection pump camshaft (9). When the engine is started, gear (7) drives fuel injection pump camshaft (9) through ring (6) and carrier (8).

Advance Timing

Maximum Timing Advance (Typical Example)
(1) Screw. (2) Setscrew. (3) Spring. (4) Valve spool. (5) Flyweights. (6) Ring. (7) Gear. (8) Carrier. (9) Fuel injection pump camshaft. (10) Body assembly. (11) Bolt. (12) Ring.

As the engine is started and begins to run, flyweights (5) move out and pull valve spool (4) to the left in the above illustration. At this point valve spool (4) is put in a position to close off the oil passage to drain in body assembly (10). Engine lubrication oil flows through the fuel injection pump housing and through a passage in fuel injection pump camshaft (9) into body assembly (10) and is stopped by valve spool (4). With oil flow stopped, oil pressure pushes body assembly (10) and carrier (8) to the left. As carrier (8) is forced to the left by oil pressure, it slides between the splines on ring (6) and the helical splines on the carrier cause the camshaft to turn in relation to gear (7). This outward motion of the body assembly (10) caused the fuel injection timing to be advanced. Timing continues to be advance until spring (3) is put under compression and spring force becomes equal to the centrifugal (outward) force of flyweight (5). At this point valve spool (4) is held in position.

Now, oil pressure moves carrier (8) to the left. This changes the valve spool position in carrier (8) and oil pressure is directed to the left side of carrier (8). The carrier moves to the right until valve spool (4) closes the oil passage. At this point carrier (8) moves slightly from left to right to maintain the timing advance needed at the engine speed (rpm) set by the governor.

NOTE: The point where timing advance begins and ends is adjusted by screw (1) and setscrew (2).

Retard Timing

Retard Timing (Typical Example)
(1) Screw. (2) Setscrew. (3) Spring. (4) Valve spool. (5) Flyweights. (6) Ring. (7) Gear. (8) Carrier. (9) Fuel injection pump camshaft. (10) Body assembly. (11) Bolt. (12) Ring.

When engine speed is reduced, flyweights (5) move in and the force of spring (3) moves valve spool (4) to the right in the above illustration. The oil flows from fuel injection pump camshaft (9), through body assembly (10), around valve spool (4) and builds up pressure to move body assembly (10) and carrier (8) to the right. This action causes the relationship between the fuel injection pump camshaft (9) and drive gear (7) to change fuel injection timing in the retarded direction.

Timing Fully Retarded (Typical Example)
(1) Screw. (2) Setscrew. (3) Spring. (4) Valve spool. (5) Flyweights. (6) Ring. (7) Gear. (8) Carrier. (9) Fuel injection pump camshaft. (10) Body assembly. (11) Bolt. (12) Ring.

Air Inlet And Exhaust System

Air Inlet System
(1) Turbocharger. (2) Air line. (3) Exhaust elbow. (4) Aftercooler core.

The components of the air inlet and exhaust system control the quality and the amount of air available for combustion. These components are the air cleaner, turbocharger, aftercooler, cylinder head, valves and valve system components, piston and cylinder, and exhaust manifold.

Air Flow Schematic
(2) Air line. (4) Aftercooler core. (5) Inlet manifold. (6) Exhaust outlet from turbocharger. (7) Turbine side of turbocharger. (8) Compressor side of turbocharger.

Inlet air is pulled through the air cleaner, compressed and heated by the compressor wheel in compressor side of turbocharger (8) to about 150°C (300°F), then pushed through the air to air aftercooler core (4) and moved to the air inlet manifold at about 43°C (110°F).

Cooling of the inlet air increases combustion efficiency, which helps to lower fuel consumption and increase horsepower output. Aftercooler core (4) is a separate cooler core installed in front of the standard engine radiator core of the truck. Ambient temperature air is moved across both cores by the engine fan and by the ram effect of the vehicles forward motion, this cools the turbocharged inlet air and the engine coolant.

From the aftercooler core the air is forced into the cylinder head to fill the inlet ports. Air flow from the inlet port into the cylinder is controlled by the intake valves.

Air Inlet And Exhaust System
(4) Aftercooler core. (6) Exhaust outlet. (7) Turbine side of turbocharger. (8) Compressor side of turbocharger. (9) Exhaust manifold. (10) Exhaust valve. (11) Intake valve. (12) Air inlet.

There are two intake and two exhaust valves for each cylinder. Intake valves open when the piston moves down on the inlet stroke. When the intake valves open, cooled compressed air from the inlet port is pulled into the cylinder. The intake valves close and the piston begins to move up on the compression stroke. The air in the cylinder is compressed. 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 the exhaust manifold. After the piston makes the exhaust stroke, the exhaust valves close and the cycle (inlet, compression, power, exhaust) starts again.

Exhaust gases from exhaust manifold (9) enter turbine side of the turbocharger (7) and cause the turbine wheel to turn. The turbine wheel is connected to the shaft which drives the compressor wheel. Exhaust gases from the turbocharger pass through the exhaust outlet pipe, the muffler and the exhaust stack.

Turbocharger

Turbocharger
(1) Pipe. (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. The compressor side of the turbocharger is connected to the aftercooler by pipe (1).

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.

Show/hide table

NOTICE
If the high idle rpm or 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.

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

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

The intake and exhaust valves are opened and closed by movement of these components: crankshaft, camshaft, lifters, push rods, rocker arms, bridges, and valve springs. Rotation of the crankshaft causes rotation of the camshaft. The camshaft gear is timed to, and driven by, a gear on the front of the crankshaft. As camshaft (9) turns, the cams of the camshaft also turn and cause lifters (8) to go up and down. This movement makes push rods (3) move rocker arms (2 and 10). Movement of the rocker arms will make intake and exhaust bridges (1 and 11) move up and down on dowels mounted in the cylinder head.

These bridges let one rocker arm open, or close, two valves (intake or exhaust) at the same time. There are two intake and two exhaust valves in each cylinder. 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.

Jake Brake

The Jake Brake permits the operator to control the speed of the vehicle on grades, curves or anytime when speed reduction is necessary, but long applications of the service brakes are not desired. In downhill operation, or any slow down condition, the engine crankshaft is turned by the rear wheels (through the differential, drive shaft, transmission and clutch). To reduce the speed of the vehicle, an application of a braking force can be made to the pistons of the engine.

The Jake Brake, when activated, does this through the conversion of the engine from a source of power to an air compressor that absorbs (takes) power. This conversion is made possible by a master to slave piston arrangement, where movement of the rocker arm for the exhaust valves of one cylinder is transferred hydraulically to open the exhaust valves of another cylinder near the top of its normal compression stroke cycle. The compressed cylinder charge is now released into the exhaust manifold.

The release of the compressed air pressure to the atmosphere prevents the return of energy to the engine piston on the expansion (power) stroke. The result is an energy loss, since the work done by the compression of the cylinder charge is not returned by the expansion process. This energy loss is taken from the rear wheels, which provides the braking action for the vehicle.

Jake Brake Components

Jake Brake Installed (Typical Example)
(1) Rear Housing. (2) Front housing. (3) Stud. (4) Support bracket.

The Jake Brake consists of two different housings, one installed in each of the valve mechanism compartments above the rocker arms and rocker arm shaft. Each housing is positioned over three cylinders, and is mounted on two support brackets (4) and on two studs (3) at the end rocker shaft brackets. Special exhaust rocker arm adjusting screws and exhaust valve bridges are necessary. Later engines have only one support bracket (4) for each housing.

NOTE: Only the engine valves and valve mechanism for the exhaust side of the cylinders are used in the operation of the Jake Brake.

A spacer is used on top of the valve cover base to permit installation of the valve cover. The increase in height with the Jake Brake installed is less than 50.8 mm (2.00 in).

Both the front and rear Jake Brake housings consist of the parts that follow: three master pistons, three slave pistons, three control valves, and one solenoid valve.

Jake Brake Operation

The Jake Brake operates with engine oil which is supplied from the rocker arm shafts. Solenoid valve (1) controls the oil flow in the housing.

When the solenoid is activated, solenoid valve (1) moves down and closes oil drain passage (14) to oil pan (18). At the same time, it opens low pressure oil passage (15) to three control valves (3). As low pressure passage (15) is filled with engine oil, control valves (3) are pushed up in their chamber against force of spring (2). At this position, a groove in control valve (3) is in alignment with high pressure oil passage (4) that supplies slave piston (10) and master piston (6).

Engine oil pressure will not lift ball check valve (9) and fill high pressure oil passage (4) and the chambers behind the slave and master pistons. This pressure moves the pistons down to a position where they will not make contact with the engine valve mechanism. When the oil pressure is the same through all the oil passages, the small spring will force ball check valve (9) back against its seat. The system is now completely charged and ready for operation with engine valve mechanism. When the solenoid is activated, the Jake Brake is ready to operate in approximately 1/5 of a second.

Master-Slave Circuit Schematic
(1) Solenoid valve. (2) Spring. (3) Control Valve. (4) High pressure oil passage. (5) Slave piston adjustment screw. (6) Master piston. (7) Rocker arm shaft oil passage. (8) Engine oil pump. (9) Ball check valve. (10) Slave piston. (11) Rocker arm. (12) Spring. (13) Rocker arm adjustment screw. (14) Oil drain passage. (15) Low pressure oil passage. (16) Exhaust valve bridge. (17) Exhaust push rod. (18) Engine oil pan. (19) Exhaust valves.

When engine push rod (17) for the exhaust valves begins to move up on its normal exhaust cycle, rocker arm (11) and adjustment screw (13) move up to make contact with master piston (6). As master piston (6) begins to move up, the oil pressure increases in passage (4) because ball check valve (9) will not let the oil out. Since there is a constant increase in pressure with the rocker arm movement, slave piston (10) is forced down against exhaust valve bridge (16) (of a different cylinder) with enough force to open exhaust valves (19).

Oil Passage Schematic (Front Housing Shown)
(1) Solenoid valve. (3) Control valves. (4) High pressure oil passages. (6) Master pistons. (10) Slave pistons. (15) Low pressure oil passage.

This master-slave circuit is designed so that master piston (6) is only moved by an engine cylinder on the exhaust stroke, while slave piston (10) opens only the exhaust valves of an engine cylinder on the compression stroke (just before top center). The braking force is constant, and the sequence is the same as the firing order of the engine, as shown in the chart that follows:

When solenoid valve (1) is in the off position, the engine oil supply passage is closed, and oil drain passage (14) to the oil pan is opened. This lets oil drain from beneath control valve (3), and spring (2) pushes control valve (3) to the bottom of the chamber. This position lets oil from high pressure oil passage (4) drain into the chamber above the control piston (chamber vents to atmosphere outside of housing). Spring (12) now moves master piston (6) up to its neutral position, away from rocker arm adjustment screw (13). The time necessary for the system to stop operation is approximately 1/10 of a second. The Jake Brake will not be able to operate now until the solenoid is activated again.

Jake Brake Controls

Control Circuit Schematic
(1) Solenoid. (2) Throttle switch. (3) Clutch switch. (4) Control switch (on dash). (5) Fuse. (6) Battery. (7) Diode.

The Jake Brake is activated electrically with three different switches connected in series in the circuit. A manually operated control switch (4) is located on the dash of the vehicle. This is a three position switch that permits an operator a selection of 100%, 50%, or no retardation (braking force).

The next switch in series is clutch switch (3). Clutch switch (3) is set to permit brake operation only when the clutch is engaged. This prevents engine stall by the Jake Brake when the drive line is not engaged with the engine.

The third switch is throttle switch (2), and it permits Jake Brake operation only when the throttle is at idle position. Any application of more throttle (fuel increase) will stop current flow and the Jake Brake will not operate.

Clutch switch (3) and throttle switch (2) work automatically after the operator control switch (4) is manually positioned. This control circuit permits any one of the three switches to prevent operation of the brake, but requires all three of the switches to be closed before operation can begin.

A small diode (7) is connected between the load side of the switch terminal and ground to protect the switch contacts from arcing.

Lubrication System

Engine Without BrakeSaver

Lubrication System Components
(1) Oil supply line to turbocharger. (2) Oil return line from turbocharger. (3) Oil cooler. (4) Oil manifold in cylinder block. (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.

Engine With BrakeSaver

Lubrication System Components (Typical Illustration)
(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, two section oil pump, oil cooler, oil filter, oil lines to and from the turbocharger and oil passages in the cylinder block. The front section of the oil pump supplies oil for lubrication of the engine. The rear section of the oil pump supplies oil for operation of the BrakeSaver. The front section of the oil pump sends oil through the oil filter and the rear section of the oil pump sends oil through the oil cooler.

Oil Flow Through The Oil Filter

Flow Of Oil (Engine Warm)
(1) Oil manifold in cylinder block. (2) Oil supply line to turbocharger. (3) Oil return line from turbocharger. (4) Oil filter. (5) Bypass valve for the oil filter. (6) Oil pan. (7) Oil pump (front section). (8) Suction bell.

With the engine warm (normal operation), oil comes from oil pan (6) through suction bell (8) to the front section of the oil pump (7). The front section of the oil pump sends oil 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 (front section) (8) Suction bell.

With the engine cold (starting conditions), oil comes from oil pan (6) through suction bell (8) to the front section of oil pump (7). When the oil is cold, an oil pressure difference in the bypass valve (5) (installed in the oil filter housing) causes the valve to open. This bypass valve gives immediate lubrication to all components when cold oil with high viscosity causes a restriction to the oil flow through oil filter (4). The front section of the oil pump then sends the cold oil 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 valve decreases and the bypass valve closes. Now there is a normal flow through the oil filter.

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

Oil Flow Through The Oil Cooler

Flow Of Oil With BrakeSaver Off (Engine Warm)
(1) Oil cooler. (2) Bypass valve for the oil cooler. (3) BrakeSaver control valve. (4) BrakeSaver. (5) Oil pump (rear section). (6) Oil pan. (7) Suction bell.

With the engine warm (normal operation), oil comes from oil pan (6) through suction bell (7) to the rear section of oil pump (5). The rear section of the oil pump sends warm oil to the BrakeSaver control valve (3). If the BrakeSaver control valve is in the OFF position, it sends the warm oil to oil cooler (1) where it is made cool. From the oil cooler, the cool oil goes back through the BrakeSaver control valve to engine oil pan (6).

Flow Of Oil With BrakeSaver On (Engine Warm)
(1) Oil cooler. (2) Bypass valve for the oil cooler. (3) BrakeSaver control valve. (4) BrakeSaver. (5) Oil pump (rear section). (6) Oil pan. (7) Suction bell.

If BrakeSaver control valve (3) is in the ON position, the oil from the rear section of oil pump (5) that goes to the BrakeSaver control valve is now sent to BrakeSaver (4). After the oil goes through the BrakeSaver, it goes back to the BrakeSaver control valve. The control valve now sends the warm oil to oil cooler (1) where it is made cool. From the oil cooler, the cool oil goes back through the BrakeSaver control valve to engine oil pan (6).

Flow Of Oil With BrakeSaver Off (Engine Cold)
(1) Oil cooler. (2) Bypass valve for the oil cooler. (3) BrakeSaver control valve. (4) BrakeSaver. (5) Oil pump (rear section). (6) Oil pan. (7) Suction bell.

When the engine is cold (starting conditions), the oil has a high viscosity. This high viscosity causes a restriction to the oil flow through oil cooler (1). When there is a restriction in the oil cooler, an oil pressure difference in bypass valve (2) causes the valve to open. When the bypass valve is open, oil from the rear section of oil pump (5) can go through the valve and drain back into engine oil pan (6).

Oil Flow In The Engine

Engine Oil Flow Schematic
(1) Bracket for rocker arm shaft. (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 (air compressor). (9) Oil passage to rocker shaft bracket and accessory drive. (10) Oil passage to idler gear shaft. (11) Oil passage to rocker shaft bracket. (12) Oil passage to the fuel injection pump housing. (13) Camshaft bearing. (14) Oil jet tubes. (15) Main bearing. (16) Oil manifold. (17) Oil passage from the oil pump to the oil cooler and filter. (18) Oil passage from the oil cooler and filter.

From oil manifold (16), oil is sent through drilled passages in the cylinder block that connect main bearings (15) and camshaft bearings (13). Oil goes through drilled holes in the crankshaft to give lubrication to the connecting rod bearings. A small amount of oil is sent through oil jet tubes (14) to make the pistons cooler. 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 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 passage (8) in the cylinder block, through passages in the timing gear housing and the accessory drive gear.

The idler gear gets oil from passage (10) in the cylinder block through a passage in the idler gear shaft installed on the front of the cylinder block.

The fuel injection pump housing gets oil from passage (12) in the cylinder block. The automatic timing advance unit gets oil from the fuel injection pump through a passage in fuel injection pump camshaft.

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.

BrakeSaver

The BrakeSaver permits the operator to control the speed reduction of the vehicle on grades, curves, or at any time when speed reduction is necessary but long applications of the service brakes are not desired.

Engine with BrakeSaver (Right Side) (Typical Illustration)

Engine with BrakeSaver (Left Side) (Typical Illustration)

BrakeSaver Components

The BrakeSaver housing (3) is fastened directly to the rear face of flywheel housing (1). The BrakeSaver adds approximately four inches to the length of the engine drive train. A rotor (2) and a ring gear plate (6) are installed between the rear flange of crankshaft (5) and flywheel (4). The ring gear plate (6) permits the use of the standard engine starter motor. The rotor turns in a space between stator (7) and BrakeSaver housing (3).

BrakeSaver Components
(1) Flywheel housing. (2) Rotor. (3) BrakeSaver housing. (4) Flywheel. (5) Crankshaft flange. (6) Ring gear plate. (7) Stator.

The engine oil pump has two sections. The front section (14) of the oil pump gives oil to the engine for lubrication. Rear section (8) of the oil pump sends engine oil through BrakeSaver control valve (16) to BrakeSaver (9). The rear section of the oil pump also sends oil through line (17) to the engine oil cooler (not shown). From the oil cooler, the cool oil goes through line (18), through baffle (13) and back into engine oil pan (15).

When the BrakeSaver is turned off, tube (10) lets the oil in the BrakeSaver rapidly go out of the BrakeSaver and back into the engine oil pan.

When the engine is cold (starting conditions), the oil has a high viscosity. This high viscosity causes a restriction to the oil flow through the oil cooler. When there is a restriction in the oil cooler, an oil pressure difference in the bypass valve (12) causes the valve to open. When the bypass valve is open, oil from the rear section of the oil pump can go through hole (11) in bypass valve (12) to drain back into engine oil pan (15).

BrakeSaver Components
(8) Oil pump (rear section). (9) BrakeSaver. (10) Tube. (11) Hole. (12) Bypass valve. (13) Baffle. (14) Oil pump (front section). (15) Engine oil pan. (16) BrakeSaver control valve. (17) Line. (18) Line.

BrakeSaver Lubrication

BrakeSaver Lubrication
(1) Oil line. (2) Orifice. (3) Piston-type ring seal. (4) Orifice. (5) Chamber. (6) Piston-type ring seal. (7) Lip-type seal. (8) Lip-type seal. (9) Oil line.

Piston ring seals (3 and 6) keep pressure oil in chamber (5) around the rotor during operation. Lip-type seals (7 and 8) prevent oil leakage from the BrakeSaver. An outside oil line (1) from the engine lubrication system sends engine oil to the BrakeSaver housing. Orifices (2 and 4) in the BrakeSaver send oil to a space between the lip seals and the piston-type ring seals at a rate of 1.24 liter/min (.33 U S gpm). This oil gives lubrication to the seals under all conditions of operation.

The spaces between the lip-type seals and the piston-type seals are connected to an outside drain line (9) that lets the oil go back to the engine oil pan.

BrakeSaver Operation

In downhill operation, the crankshaft is turned by the rear wheels (through the differential, drive shaft, transmission, and clutch). To reduce the speed of the vehicle, an application of a braking force can be made to the crankshaft. The BrakeSaver does this through the conversion of the energy of rotation into heat which is removed by the engine cooling system.

BrakeSaver Housing And Rotor
(1) BrakeSaver housing. (2) Pockets. (3) Hole. (4) Pocket. (5) Rotor.

The rotor (5) is fastened to and turns with the engine crankshaft. The rotor has pockets (4) on the outer circumference of both sides and four holes (3) to permit equal oil flow to both sides of the rotor.

The BrakeSaver housing (1) and the stator are fastened to the flywheel housing and can not turn. Both the BrakeSaver housing and the stator have pockets (2) on their inside surfaces in alignment with the pockets (4) in the rotor.

Oil Flow Through BrakeSaver
(1) BrakeSaver housing. (2) Pocket. (4) Pocket. (5) Rotor. (6) Stator.

The rotor (5) turns in the compartment made by stator (6) and BrakeSaver housing (1). When the BrakeSaver housing is in operation, engine oil comes into this compartment near the center through a passage from the bottom of the BrakeSaver housing. The rotor, turning with the crankshaft, throws this oil outward. As the oil flows outward, the shape of rotor pockets (4) send the oil into pockets (2) of the stator and BrakeSaver housing. As the rotor turns and the oil flows around the BrakeSaver compartment, it takes the shape of a spiral.

As the oil flows around the BrakeSaver compartment, it is constantly cut by the vanes (the material between the pockets) of the rotor. This cutting action gives resistance to the rotor and changes the energy of the rotor into heat in the oil. The heat is removed by the oil cooler and goes into the engine cooling system.

Oil Flow In BrakeSaver
(1) BrakeSaver housing. (5) Rotor. (6) Stator. (7) Spiral flow. (8) Air pocket.

As the BrakeSaver inlet passage opens, more oil starts to flow in a spiral shape between the rotor and the stator. Inside this spiral flow (7) of oil is an air pocket (8). As the pressure in the rotor compartment increases, the amount of oil in the spiral flow increases in thickness and the air pocket has compression. As this air pocket has compression, the amount of oil being cut by the rotor vanes has an increase.

When the BrakeSaver is in operation, the level of braking can be controlled by the inlet oil pressure, since the braking force available is in direct relation to the amount of oil that is cut by the rotor vanes. When the BrakeSaver is not in operation, the inlet passage to the rotor compartment is closed by the control valve, and there is no oil in the BrakeSaver compartment.

BrakeSaver Control

BrakeSaver Oil Flow (Off)
(1) BrakeSaver control lever. (2) Oil cooler. (3) Valve spool. (4) BrakeSaver control valve. (5) Oil pump. (6) BrakeSaver. (7) Line. (8) Oil pan.

When the BrakeSaver control lever (1) is in the OFF position, spring force holds valve spool (3) against the cover at the air inlet end of control valve (4). With valve spool (3) in this position, oil pump (5) sends engine oil from oil pan (8) through control valve (4) to oil cooler (2). From the oil cooler, the oil goes through the control valve, through line (7) and back to engine oil pan (8). With the BrakeSaver control valve in this position, no oil is sent to BrakeSaver (6).

BrakeSaver Oil Flow (Fill)
(1) BrakeSaver control lever. (2) Oil cooler. (3) Valve spool. (4) BrakeSaver control valve. (5) Oil pump. (6) BrakeSaver. (7) Line. (8) Oil pan.

When BrakeSaver control lever (1) is moved to the ON position, pressure air moves valve spool (3) to the right against the spring force. With the valve spool in this position, engine oil from oil pump (5) is sent through control valve (4) to the rotor compartment of BrakeSaver (6). From the BrakeSaver, the oil goes through the control valve, through oil cooler (2), back through the control valve, and back into the BrakeSaver.

The oil cannot go back to engine oil pan (8) because the passage through the control valve to line (7) is closed by the valve spool.

The time required to fill the BrakeSaver with pressure oil to the point of maximum braking in the BrakeSaver is approximately 1.8 seconds.

BrakeSaver Oil Flow (Operate)
(1) BrakeSaver control lever. (2) Oil cooler. (3) Valve spool. (6) BrakeSaver. (8) Oil pan.

As BrakeSaver (6) fills, the turning rotor causes an increase in the oil pressure in the BrakeSaver. Inlet oil to the BrakeSaver and outlet oil from the BrakeSaver both go into the spring bore in valve spool (3). The average of the inlet oil pressure and the outlet oil pressure in the spring bore plus the force of the spring work against the pressure air on the left end of the valve spool. When the force of the pressure oil plus the spring force become larger than the force of the pressure air, the valve spool moves to the left. This movement causes a restriction in the passage for the inlet oil and an oil pressure decrease in the BrakeSaver.

A decrease in rotor speed (normally with a decrease in vehicle speed) causes a decrease in the oil pressure in the BrakeSaver. This causes a decrease in oil pressure in the spring bore of the valve spool which lets the pressure air on the left end of the spool move the spool to the right. This movement opens the passage for the inlet oil and the oil pressure in the BrakeSaver has an increase.

An increase in rotor speed will cause an increase in the oil pressure in the BrakeSaver. This increase in oil pressure will cause the valve spool to move to the left to give a restriction to the inlet oil to the BrakeSaver.

The valve spool is constantly moving to make adjustments to the BrakeSaver inlet pressure for compensation of the changing rotor speeds caused by normal operation of the vehicle. This constant movement of the valve spool is necessary to keep the amount of braking force in the BrakeSaver at the level set by control lever (1).

During normal operation, the outlet oil from the BrakeSaver goes to oil cooler (2). From the oil cooler, some of the oil (approximately 60%) goes back to the BrakeSaver inlet and the remainder of the oil from the oil cooler goes to engine oil pan (8).

BrakeSaver Oil Flow (Drain)
(1) BrakeSaver control lever. (2) Oil cooler. (3) Valve Spool. (4) BrakeSaver control valve. (5) Oil pump. (6) BrakeSaver. (7) Line. (8) Oil pan. (9) Line.

When BrakeSaver control lever (1) is moved to the OFF position, the pressure air on the left end of valve spool (3) goes out of control valve (4). With no pressure air in the valve, the pressure oil in the spring bore plus the spring force move the valve spool against the cover at the air inlet end of the control valve. This movement closes the BrakeSaver inlet passage. The rotor in BrakeSaver (6) now pushes the oil out of the BrakeSaver, through the control valve, through line (9), and back to oil pan (8).

The time required to remove the oil from the BrakeSaver is approximately 1.5 seconds.

With the control valve in this position, oil pump (5) sends oil through oil cooler (2) and through line (7) back to the oil pan.

Operator Controls

Two types of controls are available for the BrakeSaver: a manual control and an automatic control.

Manual Control Diagram
(1) Pressure reducing valve. (2) Manual control valve. (3) BrakeSaver control lever. (4) Air pressure gauge. (5) Oil temperature gauge. (6) BrakeSaver control valve.

Manual Control

Pressure air from the truck air system is sent to pressure reducing valve (1) where the air pressure is controlled to 345 kPa (50 psi). This controlled pressure air goes to manual control valve (2).

When the operator moves BrakeSaver control lever (3) toward the ON position, pressure air is sent to BrakeSaver control valve (6). The farther lever (3) is moved toward the ON position, the higher the pressure of the air sent to the BrakeSaver control valve. An increase in air pressure in the BrakeSaver control valve causes an increase in the oil pressure in the BrakeSaver. An increase in the oil pressure in the BrakeSaver causes an increase in the braking force in the BrakeSaver. The operator can give modulation to the braking force in the BrakeSaver through the movement of BrakeSaver control lever (3).

When the BrakeSaver is turned off, the pressure air goes out of the system through a passage in manual control valve (2). This lets the pressure air out of BrakeSaver control valve (6) and removes the braking force from the BrakeSaver.

An air pressure passage gauge (4) gives the operator a relative indication of the air pressure being sent to the BrakeSaver control valve. Through the use of the indication on the air pressure gauge in relation to engine rpm, the operator can get approximately the same braking effect from the BrakeSaver time after time. This lets the operator more easily control the desired wheel speed of the vehicle.

An oil temperature gauge (5) gives the operator an indication of the ability of the engine cooling system to control the heat in the BrakeSaver during its operation. If the gauge reads too HOT, move BrakeSaver control lever (3) to the OFF position and use the service brakes to control the wheel speed of the vehicle. With the BrakeSaver off, the oil temperature will rapidly become normal again and the BrakeSaver can be used.

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NOTICE
Do not manually engage the BrakeSaver and control the wheel speed with the accelerator. The design of the cooling system is for the control of the temperature of the oil at full engine power or full BrakeSaver capacity, but not both at the same time.

Automatic Control

Automatic Control Diagram
(1) Manual control valve. (2) Pressure reducing valve. (3) Clutch switch. (4) Mode selector switch. (5) Truck ignition switch. (6) Battery. (7) Air pressure gauge. (8) Double check valve. (9) Solenoid valve. (10) Oil temperature gauge. (11) BrakeSaver control valve. (12) Throttle limit switch.

All the components of the manual control are in the automatic control and their functions are the same. In the automatic control, there is also a solenoid valve (9), a double check valve (8), and three switches (3), (4) and (5). The solenoid valve (9) (when activated) sends pressure air from the pressure reducing valve (2) to the BrakeSaver control valve (11). The solenoid valve is connected to three switches: mode selector switch (4), throttle limit switch (12) and clutch switch (3). The switches are connected to each other in series (all switches must be closed to activate the solenoid). The source of electric current is from truck ignition switch (5) which prevents the solenoid valve from being activated when the switch is OFF.

The mode selector switch (4) has two positions: MANUAL and AUTOMATIC. For automatic operation of the BrakeSaver, the mode selector switch must be in the AUTOMATIC position.

Clutch switch (3) is connected to the clutch linkage. When the clutch is engaged (clutch pedal up), the switch is closed. For automatic operation of the BrakeSaver, the clutch switch must be CLOSED (pedal up).

NOTE: In vehicles with no clutch pedal, the clutch switch is removed from the circuit.

A throttle limit switch (12) is installed in the governor. When the accelerator is released (accelerator pedal up), the governor returns to the low idle position and the switch is closed. For automatic operation of the BrakeSaver, the throttle limit switch must be closed (accelerator pedal up).

When the switches are closed, the electric current from truck ignition switch (5) opens solenoid valve (9). When the solenoid valve is open, full air pressure [345 kPa (50 psi)] is sent through the double check valve (8) to BrakeSaver control valve (11). The double check valve keeps the pressure air from going out of the system through the manual control valve (1) when the control lever of manual control valve (1) is not in use. It also keeps the pressure air from going out of the system through solenoid valve (9) when the manual control is in use.

Because the solenoid valve sends full air pressure to the BrakeSaver control valve, there is no modulation in the AUTOMATIC position.

When the mode selector switch (4) is in the AUTOMATIC position and the accelerator pedal is released (pedal up), the BrakeSaver is operating at its maximum capacity. When the clutch is released (pedal down) the BrakeSaver goes off. When the clutch is engaged again (pedal up), the BrakeSaver comes back on. A light pressure on the accelerator pedal turns the BrakeSaver off and lets the vehicle run freely. More pressure on the accelerator pedal sends fuel to the engine.

When the BrakeSaver is turned off, the pressure air goes out of the system through a passage in manual control valve (1) or in solenoid valve (9). This lets the pressure air out of BrakeSaver control valve (11) and removes the braking forces from the BrakeSaver.

Manual control valve (1) can be operated with mode selector switch (4) in the AUTOMATIC position. During normal operation, the solenoid valve will send full air pressure to the BrakeSaver control valve and remove the effects of the manual control valve. If there is a failure in the electrical system when the mode selector switch is in the AUTOMATIC position, the manual control valve will have an effect.

Cooling System

This engine has a pressure type cooling system equipped with a shunt line (6).

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.

NOTE: In air to air aftercooled systems, a coolant mixture with a minimum of 30% ethylene glycol base antifreeze must be used for efficient water pump performance. This mixture keeps the cavitation temperature range of the coolant, high enough for efficient performance. Dowtherm 209 Antifreeze can not be used because it does not raise the water pump cavitation temperature of the coolant high enough.

Cooling System (Engine Warm)
(1) Cylinder head. (2) Aftercooler. (3) Water temperature regulator. (4) Outlet hose. (5) Vent tube. (6) Shunt line. (7) Water elbow. (8) Water pump. (9) Aftercooler inlet line. (10) Cylinder block. (11) Oil cooler. (12) Inlet hose. (13) Radiator.

In operation water pump (8) sends most of the coolant from radiator (13) to oil cooler (11). In systems with jacket water aftercooler, a small amount of coolant goes to aftercooler (2).

The coolant from oil cooler (11) and aftercooler (2) goes through a bonnet and elbow into cylinder block (10). Inside the cylinder block, the coolant goes around the cylinder liners and up through the water directors into the cylinder head. The water directors send the flow of coolant around the valves and the passages for exhaust gases in the cylinder head. The coolant then goes to the front of the cylinder head. At this point, water temperature regulator (3) controls the direction of coolant flow.

If the coolant temperature is less than normal for engine operation, water temperature regulator (3) is closed. The coolant flows through the regulator housing and elbow (7) back to water pump (8).

If the coolant is at normal operating temperature (engine warm) water temperature regulator (3) is open and the coolant flows to radiator (13) through outlet hose (4). The coolant is made cooler as it moves through the radiator. When the coolant gets to the bottom of the radiator, it goes through inlet hose (12) and into the water pump.

NOTE: Water temperature regulator (3) is an important part of the cooling system. It divides coolant flow between radiator (13) and bypass [water elbow (7)] as necessary to maintain the correct temperature. If the water temperature regulator is not installed in the system, there is no mechanical control, and most of the coolant will take the path of least resistance through the bypass. This will cause the engine to overheat in hot weather. In cold weather, even the small amount of coolant that goes through the radiator is too much, and the engine will not get to normal operating temperatures.

Cooling System Components
(2) Aftercooler. (9) Aftercooler inlet line. (11) Oil cooler. (14) Water temperature regulator housing.

Shunt line (6) gives several advantages to the cooling system.

1. The shunt line gives a positive coolant pressure at the water pump inlet to prevent pump cavitation.

2. A small flow of coolant constantly goes through shunt line (6) to the inlet of water pump (8). This causes a small amount of coolant to move constantly through vent tube (5) between the lower and upper compartment in the radiator top tank. Since the flow through the vent tube is small and the volume of the upper compartment is large, air in the coolant comes out of the coolant as it goes into the upper compartment.

3. The shunt line is a fill line when the cooling system is first filled with coolant. This lets the cooling system fill from the bottom to push any air in the system out the top.

Coolant Flow From Aftercooler
(2) Aftercooler. (15) Elbow.

Engines Equipped With A BrakeSaver

The cooling system for an engine with a BrakeSaver is the same as the cooling system for an engine with no BrakeSaver. The oil cooler on an engine with a BrakeSaver is larger but it is still found in the same location on the engine. It has the same water flow through it as the oil cooler on an engine with no BrakeSaver.

Coolant For Air Compressor

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.

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

Coolant Conditioner (An Attachment)

Coolant Conditioner
(1) Coolant conditioner element. (2) Air compressor. (13) Coolant inlet (from water pump). (14) Coolant outlet (to air compressor).

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

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

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

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

Schematic of Cooling System with Coolant Conditioner
(1) Coolant conditioner element. (2) Air compressor. (3) Coolant outlet (to radiator). (4) Temperature regulator housing. (5) Coolant bypass line. (6) Water pump. (7) Radiator. (8) Coolant inlet (from radiator). (9) Engine oil cooler. (10) Cylinder liner. (11) Aftercooler. (12) Shunt line.

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

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

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.

Charging System Components

Alternator

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

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

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

These stronger lines of force now increase the amount of AC current produced in the stator windings. The increased speed of the rotor assembly also increases the current and voltage output of the alternator.

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

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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 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 starter motor circuit with a low current start switch circuit.

b. Engages the starter 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 starter 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 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 holdin windings are in operation for the extended period of time it takes to start the engine. The solenoid will now take less current from the battery, and heat made by the solenoid will be kept at an acceptable level.

Starter Motor

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

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

Starter Motor Cross Section
(1) Field. (2) Solenoid. (3) Clutch. (4) Pinion. (5) Commutator. (6) Brush Assembly. (7) Armature.

Wiring Diagrams For Starting Systems

12 Volt Starting System

NOTE: Numbers on wires show wire size.

12 Volt Starting System
(1) Ammeter. (2) Lights. (3) Key Switch. (4) Gauges. (5) Shutoff solenoid (energized to run). (6) Alternator. (7) Starter motor. (8) Switch. (9) Battery (12 volt).

24 Volt Starting System

System has two 12 volt batteries and a series parallel switch.

NOTE: Numbers on wires show wire size.

24 Volt Starting System
(1) Ammeter. (2) Lights. (3) Key Switch. (4) Gauges. (5) Alternator. (6) Series-parallel switch. (7) Shut-off solenoid. (8) Start motor (24 volt). (9) Battery (12 volt). (10) Battery (12 volt).

Wiring Diagrams For Grounded Electrical Systems

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

(Regulator Inside Alternator)

Charging System
(1) Ammeter. (2) Alternator. (3) Battery.

Charging System With Electric Starter Motor
(1) Start switch. (2) Ammeter. (3) Alternator. (4) Battery. (5) Starter motor.

Wiring Diagrams For Insulated Electrical Systems

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

(Regulator Inside Alternator)

Charging System
(1) Ammeter. (2) Alternator. (3) Battery.

Charging System With Electric Starter Motor
(1) Start switch. (2) Ammeter. (3) Alternator. (4) Battery. (5) Starter motor.

The charts that follow give the correct wire sizes and color codes used in the diagrams for Grounded And Insulated Electrical Systems.