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| Illustration 1 | g00332354 |
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 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).
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| Illustration 2 | g00332357 |
Location of the fuel system components (typical example) (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 | |
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) .
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 | g00332494 |
The location of the fuel system components (typical example) (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 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.
Fuel Injection Pump
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| Illustration 4 | g00332516 |
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, through the fuel line and to the injection valve. The high pressure fuel flows into the inlet passage which opens into the pressure relief passage (4) that is in the plunger. The pressure in the chamber decreases and check valve (3) closes.
The amount of fuel that is forced through check valve (3) is determined by the length of time that the inlet passage (2) is closed. The pressure relief passage (4) is used in order to control the state of the inlet passage. The design of the pressure relief passage allows the rotation of the plunger to control fuel metering for each pump. 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 play between the racks and link (10) is controlled by a spring that loads lever (11). 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 Nozzles
The fuel injection nozzle is installed into an adapter through the cylinder head into the combustion chamber. The fuel injection pump sends fuel with high pressure to the fuel injection nozzle. Then, the fuel is made into a fine spray for good combustion.
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| Illustration 5 | g00354279 |
Fuel injection nozzle (typical example) (1) Carbon dam (2) Seal (3) Passage (4) Filter screen (5) Inlet passage (6) Orifice (7) Valve (8) Diameter (9) Spring | |
Seal (2) is positioned against the nozzle adapter. This prevents leakage of compression from the cylinder. Carbon dam (1) keeps carbon out of the bore in the nozzle adapter.
Fuel with high pressure from the fuel injection pump flows into the inlet passage (5). Fuel then flows through filter screen (4) and into passage (3). The fuel continues to the area below diameter (8) of valve (7). When the fuel pressure against diameter (8) becomes greater than the force of spring (9), valve (7) lifts up.
Valve (7) lifts up when the fuel pressure rises above the valve opening pressure of the fuel injection nozzle. When valve (7) lifts up, the tip of the valve comes off the nozzle seat, and the fuel will flow through the 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. This stops the flow of fuel to the combustion chamber.
Note: The fuel injection nozzle cannot be disassembled, and no adjustments can be performed.
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 the movement of the fuel rack. The valve directs pressure oil to either side of a piston that controls rack position. 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 | g00332517 |
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 in order to get a reduction of fuel to the engine. When these two forces are in balance, the engine runs at a constant rpm.
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| Illustration 7 | g00456122 |
(A) Pressure oil (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 | |
Governor in increased load position
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) .
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 | g00456195 |
(A) Pressure oil (B) Drain oil (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 | |
Governor in decreased load position
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 dashpot piston (4)
- A dashpot spring (6)
- A collar 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 | g00332522 |
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. As air gets into the dashpot chamber (3), this will allow 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.
Mechanical Governor
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.
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| Illustration 10 | g01027696 |
Mechanical governor (1) Collar (2) Bolt (3) Lever assembly (4) Upper spring seat (5) Weights (6) Governor spring (7) Lower spring seat (8) Thrust bearing (9) Valve (10) Upper oil passage in piston (11) Piston (12) Lower oil passage in piston (13) Sleeve (14) Oil passage in cylinder (15) Drive assembly (16) Cylinder (17) Pin (18) Lever | |
The governor has governor flyweights (5) driven by the engine through the drive assembly (15). The governor has governor spring (6), valve (9) and piston (11). The valve and the piston are connected to one fuel rack through pin (17) and lever (18). The pressure oil for the governor arrives from the governor's oil pump that is on top of the injection pump housing. The oil that is used is from the engine lubrication system. Pressure oil flows through passage (14) and around sleeve (13). The throttle lever (governor control) controls the compression of governor spring (6). Compression of the spring always pushes down in order to provide more fuel to the engine. The centrifugal force of governor flyweights (5) always pulls in order to reduce the amount of fuel to the engine. When these two forces are in balance, the engine runs at the desired rpm (governed rpm).
The governor valve (9) is shown in the position when the force of the governor spring is in balance.
When the engine load increases, the engine rpm decreases and the rotation of governor flyweights (5) will slow. The governor flyweights will move inward. Governor spring (6) moves valve (9) downward. This allows the oil flow from the lower passage (12) around the valve (9) and through the upper passage (10) to fill the chamber behind piston (11). This pressure oil pushes the piston (11) and the pin (17) downward in order to deliver more fuel to the engine. The upper portion of the valve inhibits the oil flow around the valve. Engine rpm goes up until the rotation of the governor flyweights is fast enough to be in balance with the force of the governor spring.
When there is a reduction in engine load, there will be an increase in engine rpm and a corresponding increase in the rotation of governor flyweights (5). This will move valve (9) upward. This stops oil flow from the lower passage (12). Further, the oil that is above piston (11) flows around valve (9). Now, the pressure between the sleeve (13) and piston (11) pushes the piston and pin (17) upward. This causes a reduction in the amount of fuel to the engine. Engine rpm will decrease until the centrifugal force (rotation) 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 the desired rpm (governed rpm).
When engine rpm is at low idle, a spring-loaded plunger in lever assembly (3) comes in contact with a shoulder on the adjustment screw for low idle. To stop the engine, push the throttle lever to the vertical position. This will allow the spring-loaded plunger to move over the shoulder on the low idle adjustment screw. The fuel rack then moves in order to shut off the flow of fuel. With no fuel to the engine cylinders, the engine will stop.
The governor oil pump supplies oil to the valve (9) in order to increase the governor's power and response. Oil from the governor's oil pump provides lubrication to the following components:
- weight support and gear
- thrust bearing
- drive gear bearing
The other parts of the governor are provided lubrication from splash lubrication. Oil from the governor drains into the fuel injection pump housing. The oil then drains into the cylinder block.
Fuel Ratio Control
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| Illustration 11 | g01028003 |
Fuel ratio control (engine stopped) (1) Inlet air chamber (2) Valve (3) Diaphragm assembly (4) Oil drains (5) Pressure oil chamber (6) Large oil passages (7) Oil inlet (8) Small oil passages (9) Oil outlet (10) Fuel rack linkage (11) Valve | |
With the engine stopped, valve (11) is in the fully extended position. The movement of fuel rack linkage (10) is not limited by valve (11). When the engine is started, oil flows through oil inlet (7) into pressure oil chamber (5). From chamber (5), the oil flows through large oil passages (6) to the inside of valve (11). The oil then flows out of the small oil passages (8) to oil outlet (9). A hose assembly connects inlet air chamber (1) to the inlet air system. As the inlet air pressure increases, the diaphragm assembly (3) begins to move downward. Valve (2) is a part of the diaphragm assembly., The valve is used to close the large oil passages (6) and the small oil passages (8). When these passages are closed, oil pressure increases in chamber (5). This increase in oil pressure moves valve (11) upward. The control is now ready for operation. When the governor control is moved in order to increase fuel to the engine, Valve (11) limits the movement of fuel rack linkage (10) in the fuel on direction. The oil in chamber (5) acts as a restriction to the movement of valve (11) until inlet air pressure increases.
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| Illustration 12 | g01028023 |
Fuel ratio control (stable rpm and load) (1) Inlet air chamber (2) Valve (5) Pressure oil chamber (6) Large oil passages (8) Small oil passages (11) Valve | |
As the inlet air pressure increases, valve (2) moves downward. This allows oil from chamber (5) to drain through large oil passages (6) and out through oil drains (4). Valve (11) is allowed to move downward so that fuel rack linkage (10) can gradually increase the fuel to the engine. The control is designed to prevent an increase in the fuel delivery until the air pressure in the inlet manifold is high enough for complete combustion. This prevents a buildup of large amounts of exhaust smoke that can be caused by an air/fuel mixture with too much fuel. The fuel ratio control acts very quickly and adjustments to the air/fuel ratio take a very short time. No change in engine acceleration can be felt.
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| Illustration 13 | g01028050 |
Fuel ratio control (increase in inlet air pressure) (1) Inlet air chamber (2) Valve (4) Oil drains (5) Pressure oil chamber (10) Fuel rack linkage (11) Valve | |
Automatic Timing Advance Unit
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| Illustration 14 | g00354280 |
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 will force the flange to rotate 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.
This unit will advance the fuel injection pump camshaft for approximately 2% when the engine speed is increased from low idle to 1100 rpm. The timing advance unit is not an adjustable component.