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| Illustration 1 | g01246542 |
Fuel flow schematic (1) Fuel inlet line for the injection pump housing (2) Damper (3) Adapter with orifice (4) Injection pump housing (5) Fuel return line (6) Injection valve (7) Junction block (8) Fuel priming pump (9) Bypass valve (10) Fuel tank (11) Fuel supply line (12) Primary fuel filter (13) Fuel pressure gauge (14) Main fuel filters (15) Pressure relief valve (16) Fuel transfer pump | |
These engines have a pressure type fuel system. There is one injection pump and one fuel injector nozzle for each cylinder. The injection pumps are in the pump housing (4) on the top front of the engine. The fuel injection nozzles are located in the fuel injection adapters. The fuel injection adapters are under the valve covers.
The fuel transfer pump (16) pulls the fuel from the fuel tank (10) through the primary fuel filter (12). The fuel flows from the primary fuel filter (12) to the fuel priming pump (8) and through the main fuel filters (14). The fuel then flows to the manifold of the injection pump housing. The fuel in the manifold of the injection pump housing flows to the injection pumps. The injection pumps are in time with the engine. The injection pumps push fuel at a very high pressure to the injection valves (6) .
A damper (2) is located on the inlet elbow of the fuel manifold (19). The damper (2) reduces the shock loads that are caused by the injection pumps. Some of the fuel in the fuel manifold is constantly sent through a restriction orifice (3). This removes air from the system. This restriction keeps the fuel pressure high. The restriction also controls the amount of fuel that goes back to the fuel tank through the return line (5).
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| Illustration 2 | g01246543 |
Location of the fuel system components (1) The fuel inlet line for the injection pump housing (2) Damper (3) Adapter with orifice (5) Fuel return line (11) Fuel supply line (16) Fuel transfer pump (17) The fuel outlet line from the transfer pump and the inlet line to the main filters (18) The nut for a fuel injection line at the injection pump (19) The fuel manifold across the injection pump housing (20) Adapter through the valve cover base | |
The fuel priming pump (8) is used to fill the system with fuel. The fuel priming pump also removes air from the low pressure side of the fuel system. The low pressure side of the fuel system consist of the fuel filter, the fuel lines and components.
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| Illustration 3 | g01246544 |
The location of the fuel system components (1) The fuel inlet line to the injection pump housing (5) The fuel return line to the tank (7) Junction block (8) Fuel priming pump (11) Fuel supply line (14) Main fuel filters (17) The fuel outlet line from the transfer pump and the inlet line to the main filters | |
The fuel transfer pump has a bypass valve and a check valve. The bypass valve controls the maximum pressure of the fuel. The extra fuel goes to the inlet of the pump. The check valve allows the fuel from the tank to go around the transfer pump gears when the priming pump is used.
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| Illustration 4 | g01246545 |
The location of the fuel system components (1) The fuel inlet line for the injection pump housing (5) The fuel return line (7) Junction block (8) Fuel priming pump (11) Fuel supply line (14) Main fuel filter (17) The fuel outlet line from the transfer pump and the inlet line to the main filter | |
Fuel Injection Pump
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| Illustration 5 | g01246546 |
The cross section of the fuel injection pump housing (1) Fuel manifold (2) Inlet passage (3) Check valve (4) Pressure relief passage (5) Pump plunger (6) Spring (7) Gear (8) Fuel rack (left) (9) Lifter (10) Link (11) Lever (12) Camshaft | |
The rotation of the cams on the camshaft (12) cause the lifters (9) and the pump plungers (5) to move up and down. The stroke of each pump plunger is always the same stroke. The force of the springs (6) hold the lifters (9) against the cams of the camshaft.
The pump housing is in a shape of a V. The shape is similar to the engine cylinder block. There is the same number of pumps on each side.
When the pump plunger moves down, the fuel from the fuel manifold (1) flows through the inlet passage (2). The fuel then fills the chamber that is above the pump plunger (5). When the plunger moves up, the plunger closes the inlet passage.
The pressure of the fuel in the chamber above the plunger increases until the pressure is high enough to cause the check valve (3) to open. The high pressure fuel flows through the check valve to the injection valve and through the fuel line until the inlet passage opens into the pressure relief passage (4) in the plunger. The pressure in the chamber decreases and check valve (3) closes.
The amount of fuel forced through the check valve (3) is determined by the amount of time that the inlet passage (2) is closed. The pressure relief passage (4) will control the amount of time the inlet passage is closed. The amount of time the inlet passage is closed can be changed because of the design of the passage. This can be changed by rotating the plunger. When the governor moves the fuel racks (8), the fuel racks move the gears (7) that are fastened to the plungers (5). This causes a rotation of the plungers.
The governor is connected to the left rack. The spring load, located on the lever (11), removes the play between the racks and the link (10). The fuel racks are connected by the link (10). The fuel racks move in opposite directions. When one rack moves in, the other rack moves out.
Fuel Injection Valves and Nozzles
The injection valves are located within the fuel injection adapters. The fuel injection adapters are installed in the cylinder head.
The fuel injection pump sends fuel with high pressure to the fuel injection valves. The fuel injection valves change the fuel to the correct spray pattern for good combustion in the cylinders. The fuel injection valves will not open until a very high pressure is reached. Once this pressure is reached, the fuel injection valves open quickly. The fuel is released directly into the engine cylinder through six orifices in the tip of each nozzle.
Hydramechanical Governor with Dashpot
The governor controls the amount of fuel that is needed by the engine to maintain a desired rpm. The governor maintains a constant rpm for variable engine loads.
When the engine is operating, the balance between the centrifugal force of the governor flyweights and the force of the governor control on the governor spring, controls the movement of a valve and indirectly, controls the movement of the fuel rack. The valve directs pressure oil to either side of a rack positioning piston. The position of the valve controls the rack. The amount of fuel to the engine is controlled by the rack and load conditions.
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| Illustration 6 | g01246548 |
Hydramechanical governor with dashpot (1) Collar (2) Collar bolt (3) Dashpot chamber (4) Dashpot piston (5) Lever assembly (6) Dashpot spring (7) Governor spring (8) Governor flyweights (9) Valve (10) Cylinder (11) Drive assembly (12) Pin (13) Lever | |
The governor has governor flyweights (8) that are driven by the engine through the drive assembly (11). The governor has a governor spring (7), a valve (9) and a piston. The valve and the piston are connected to one fuel rack through pin (12) and lever (13) .
The governor control is connected to the governor control lever. The governor control controls the compression of the governor spring (7). The compression of the spring gives more fuel to the engine. The centrifugal force of the governor flyweights (8) always pulls up. This reduces the amount of fuel to the engine. When these two forces are in balance, the engine runs at a constant rpm.
The governor oil pump is on top of the fuel injection pump housing. The governor oil pump sends engine oil under pressure to the governor cylinder (10) through passage (18) around sleeve (19).
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| Illustration 7 | g01246550 |
Governor in increased load position (7) Governor spring (8) Governor flyweights (9) Valve (10) Cylinder (12) Pin (14) The oil drain passage for the piston (15) The upper oil passage in the piston (16) Piston (17) The lower oil passage in the piston (18) The oil passage in the cylinder (19) Sleeve | |
When the load on the engine increases, the engine rpm decreases. This will cause a slower rotation of the governor flyweights (8). The governor flyweights will move toward each other. The governor spring (7) moves valve (9). This will open the oil passages in piston (16). This will also close the oil drain passage (14). This will allow the oil to flow from passage (17), around valve (9), and through passage (15). This will fill the chamber above piston (16). The pressure oil pushes down on piston (16) and pin (12). This gives more fuel to the engine. Engine rpm increases until the rotation of the governor flyweights is fast enough to be in balance with the force of the governor spring.
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| Illustration 8 | g01246553 |
Governor in decreased load position (7) Governor spring (8) Governor flyweights (9) Valve (10) Cylinder (12) Pin (14) The oil drain passage for the piston (15) The upper oil passage in the piston (16) Piston (17) The lower oil passage in the piston (18) The oil passage in the cylinder (19) Sleeve | |
When there is a reduction in load on the engine, there will be an increase in engine rpm and the rotation of the governor flyweights (8) will increase. This will move valve (9) to a higher position. This stops the oil flow from passage (17) and the oil pressure above piston (16) goes out around valve (9) through the top of the piston (16). The pressure between sleeve (19) and piston (16) pushes the piston and pin (12) to a higher position. This causes a reduction in the amount of fuel to the engine. The engine rpm decreases until the centrifugal force of the governor flyweights is in balance with the force of the governor spring. When these two forces are in balance, the engine will run at a constant rpm.
When the engine rpm is at LOW IDLE, a spring loaded plunger in the lever assembly (5) is in contact with a shoulder on the adjustment screw for low idle. To stop the engine, move the switch to the "OFF" position. This will cause the shutoff solenoid to move the spring loaded plunger over the shoulder on the low idle adjustment screw. This will move the fuel racks to the fuel shutoff position. With no fuel to the engine cylinders, the engine will stop. To stop the engine manually, turn the shutoff lever on the governor housing to the shutoff position.
The oil from the governor pump lubricates the following components:
- The governor weight support and gear
- The thrust bearing under the governor spring
- The drive gear bearing
The other parts of the governor receive lubrication from splash lubrication. Splash lubrication is oil that is thrown by other parts. The oil flows from the governor to the housing for the fuel injection pumps.
Electric set engines need a governor that has better control over the engine speed range. A standard hydramechanical governor can not provide this function. The following parts are added to the basic hydramechanical governor.
- A piston (4)
- A spring (6)
- A bolt (2)
- An oil reservoir in the shutoff housing
- Two adjustment screws (20) and (21)
These parts control the flow of oil into the dashpot chamber (3) and out of the dashpot chamber (3). The dashpot chamber (3) is above the dashpot piston (4). The oil flows through internal oil passages. The correct oil flow into the dashpot chamber (3) and out of the dashpot chamber (3) causes a more precise movement of the governor spring seat. This allows the governor to accurately control the engine speed.
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| Illustration 9 | g01246555 |
Side view of governor (20) The adjustment screw for the dashpot (21) Adjustment screw for supply oil to the reservoir | |
The oil for the action of the dashpot comes from the engine lubrication system. The adjustment screw (21) controls the oil flow from the lubrication system into the reservoir. The reservoir has an oil overflow that sends the oil back to the mechanical area of the governor. Too much oil flow to the reservoir will fill the governor with oil. This will decrease the engine performance. Too little oil flow does not give enough oil to the reservoir. The decrease in oil will cause the governor to hunt. This will result in the constant increase in engine speed and the decrease in engine speed. Air gets into the dashpot chamber (3). This air causes the dashpot piston (4) and the lower governor spring seat to move faster.
The dashpot adjustment screw (20) causes a restriction to the oil flow into the dashpot chamber (3) and out of the dashpot chamber (3). Too much oil flow will allow the lower governor spring seat to move faster. This will allow the governor to hunt. Too little oil flow causes a slower action by the governor.
Automatic Timing Advance Unit
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| Illustration 10 | g01246556 |
Automatic timing advance unit (1) Flange (2) Weight (3) Springs (4) Slide (5) Drive gear (6) Camshaft | |
The automatic timing advance unit is installed on the front of the camshaft (6) for the fuel injection pump. The timing gears drive the automatic timing advance unit. The drive gear (5) for the fuel injection pump is connected to the camshaft (6) by the following components:
- Two weights (2)
- Springs (3)
- Two slides (4)
- Flange (1)
Each one of the slides (4) is held on the drive gear (5) by a pin. The weights (2) in the timing advance are driven by two slides (4). These slides (4) fit into notches that are made on an angle in the weights (2). When the centrifugal force (rotation) moves the weights (2) outward against the springs (3), the guides in the flange and the slides on the gear make the flange turn in relation to the gear. Since the flange is connected to the camshaft for the fuel injection pump, the fuel injection timing is also changed.
The unit advances the fuel injection pump camshaft 2% between approximately low idle and 1100 rpm. No adjustment can be made in the timing advance unit.