 | |
| Illustration 1 | g00637221 |
Air Inlet And Exhaust System With Turbocharger For A High Pressure Fuel System (1) Gas pressure regulator. (2) Balance line. (3) Carburetor. (4) Air cleaner. (5) Turbocharger. (6) Gas Supply. (7) Governor. (8) Aftercooler. (9) Air inlet manifold. (10) Cylinder. (11) Differential pressure regulator. (12) Exhaust manifold. | |
 | |
| Illustration 2 | g00637450 |
Air Inlet And Exhaust System With Turbocharger For A Low Pressure Fuel System (AA) Exhaust gas. (BB) Air and gas to cylinders. (CC) Gas supply. (DD) Low pressure gas. (EE) Air inlet. (1) Gas pressure regulator. (2) Balance line. (3) Carburetor. (4) Air cleaner. (5) Turbocharger. (6) Gas supply. (7) Governor. (8) Aftercooler. (9) Air inlet manifold. (10) Cylinder. (11) Differential pressure regulator. (12) Exhaust manifold. | |
Some air inlet and exhaust systems have an attachment for a gas shutoff valve in the supply line. This valve is electrically operated from the ignition system. The valve can be operated manually in order to stop the engine. When the engine has been stopped, the valve must be manually reset.
Engine installations that use dual fuel systems have similar components to the components in the above illustration. Engines that use dual fuel systems use a negative pressure regulator for one of the fuels. These engines have a load valve that can be used to adjust one of the fuels. Adjustments for differences in the BTU content of the gas that is being used can be made with the additional components. Engines that use dual fuel systems can change fuels automatically. Engine timing must be adjusted when the fuel is switched.
Changes in engine load and changes in the fuel that is being burned cause changes in the rpm of the turbine wheel. Changes in engine load also cause changes in the turbine wheel of the turbocharger (5) .
When the turbocharger gives a pressure boost to the inlet air, the temperature of the air increases. A water cooled aftercooler (8) is installed between the carburetor (3) and the air inlet manifold (9). The aftercooler reduces the air temperature from the turbocharger.
Aftercooler
The aftercooler is installed on the top of the inlet manifold. Water flow through the aftercooler lowers the temperature of the inlet air from the turbocharger. With cooler air, an increase in weight of the air will permit more fuel to burn. This gives an increase in power.
Gas Pressure Regulator
 | |
| Illustration 3 | g00579946 |
Regulator Operation (1) Spring chamber. (2) Spring. (3) Locknut. (4) Adjustment screw. (5) Balance line. (6) Outlet. (7) Main diaphragm. (8) Lever side chamber. (9) Lever. (10) Pin. (11) Valve stem. (12) Inlet. | |
The fuel pressure regulator is on the left side of the engine. Adjustment of the regulator is made by turning the adjustment screw (4) .
Gas flows through the inlet (12), main orifice, valve disc, and the outlet (6). Outlet pressure is felt in the chamber (1). This outlet pressure comes from the turbocharger boost from the balance line (5). The diaphragm (7) is pushed against the spring. This moves the lever (9) at pin (10). The valve stem (11) moves the valve disc (not shown) in and out. This changes the amount of gas flow.
When the inlet orifice is closed, gas is pulled from the lever side of chamber (8). The gas now flows through outlet (6). This reduces the pressure in chamber (8). The pressure in the chamber is now less than the pressure in the chamber on the spring side. Force of spring and air pressure in the chamber on the spring side moves the diaphragm toward the lever. The lever moves downward and the valve disc opens. When the valve disc is open, additional gas is able to flow to the carburetor.
The regulator sends gas to the carburetor at a preset amount when the pressure on both sides of the diaphragm is equal.
High Pressure Carburetor
 | |
| Illustration 4 | g00579948 |
Operation of the carburetor (1) Connection for the balance line. (2) Air horn. (3) Outer chamber. (4) Fuel valve. (5) Tube for fuel outlet. (6) Spring. (7) Load valve. (8) Chamber. (9) Inner chamber. (10) Ring. (11) Diaphragm. (12) Fuel inlet. (13) Throttle plate. | |
 | |
| Illustration 5 | g00579951 |
Operation of the carburetor (View A-A) (1) Connection for the balance line. (2) Air horn. (7) Load valve. (12) Fuel inlet. | |
Air goes into the carburetor through air horn (2). The air fills the outer chamber (3). Air goes into inner chamber (9). This inner chamber is also known as the mixing chamber. The air goes into this mixing chamber by moving the diaphragm (11) away from ring (10). There are three diaphragms in this carburetor. Fuel flows into the carburetor through fuel inlet (12). The fuel flows past the load valve (7) and flows to the center of the carburetor. Fuel flows into tube (5) which is for the fuel outlet. Fuel valve (4) is fastened to diaphragm (11). When the diaphragm has moved away from the ring (10), fuel flows through the fuel valve (4). The fuel then flows into chamber (9). The mixture of fuel and air that is in the inner chamber (9) flows past the throttle plate (13). The fuel flows into the inlet manifold.
When the engine is stopped, spring (6) holds diaphragm (11) against ring (10). Fuel valve (4) is held closed. No air or fuel can go to the inner chamber (9). When the engine is started, a vacuum is created in the cylinders. This vacuum is created from the intake strokes of the pistons. The intake strokes of the pistons create a low pressure condition in the inner chamber (9). This low pressure goes through small holes behind the diaphragm. The low pressure is felt by chamber (8) because of the diaphragm. This permits the pressure in chamber (8) to balance with the low pressure condition in the inner chamber. When the inlet pressure on the diaphragm (11) is higher than the spring force, the diaphragm moves out. Fuel valve (4) moves out. Air and fuel are now able to go into the inner chamber.
 | |
| Illustration 6 | g00637475 |
Carburetor For A G3412 Engine (14) Load valve. (15) Carburetor. | |
 | |
| Illustration 7 | g00637501 |
Carburetor for a G3412 Engine (16) Spring. (17) Jet. (18) Valve. (19) O-Ring seal. | |
Low Pressure System
 | |
| Illustration 8 | g00590697 |
(1) Carburetor. (2) Turbocharger. (3) Air cleaner. | |
 | |
| Illustration 9 | g00590626 |
(4) Fuel inlet line. (5) Balance line. (6) Gas pressure regulator. | |
From the main gas supply line, gas enters the gas pressure regulator (6). The gas pressure regulator provides a low pressure flow of fuel. This fuel flows to the inlet line (4). As the compressor wheels of the turbocharger (2) rotate, fuel at low pressure is drawn through the fuel inlet line to the carburetor (1). The carburetor is located between the air cleaner (3) and the compressor side of the turbocharger. The carburetor mixes the fuel with intake air from the air cleaner. The air/fuel mixture is pulled into the turbocharger. This mixture is compressed. This compressed mixture goes to the aftercooler. From the aftercooler, the mixture goes to the throttle. The throttle is connected by a linkage to the governor. The throttle controls the flow of the mixture into the intake manifold plenum. The air/fuel mixture in the intake manifold plenum enters the cylinder through the cylinder inlet valves. The mixture is compressed and ignited by the spark plug.
Turbocharged engines have a balance line (5). This balance line is connected between the carburetor air inlet and the atmospheric vent of the gas pressure regulator. The inlet air pressure from the carburetor goes through the balance line. The inlet air pressure is directed to the upper side of the regulator diaphragm. This action controls gas pressure at the carburetor. The inlet air pressure and the spring force act on the diaphragm. This force ensures that the gas pressure will be correct. The gas pressure should always be greater than inlet air pressure regardless of load conditions.
For example, when the engine accelerates, the air pressure increases. A small amount of the increased air pressure is directed to the gas pressure regulator. The movement of the control will increase the gas pressure to the carburetor.
By this method, the correct differential pressure between the gas pressure regulator and the carburetor air inlet is controlled. A turbocharged engine will not develop full power if the balance line is disconnected.
A valve assembly for gas pressure is located in the fuel inlet line. This valve assembly is used to adjust emission levels at full load and at rated speed.
Valve System Components
The valve system components control the flow of inlet air and exhaust gases. The inlet air and exhaust gases flow in and out of the cylinders during engine operation.
The crankshaft gear drives the camshaft gear. The camshaft gear must be timed to the crankshaft gear. This results in the correct relation between piston movement and valve movement.
The camshaft has two cams for each cylinder. One cam controls the exhaust valves while the other cam controls the inlet valves.
 | |
| Illustration 10 | g00327369 |
Valve system components (1) Inlet valve bridge. (2) Inlet rocker arm. (3) Valve pushrod. (4) Rotocoil. (5) Valve spring. (6) Valve guide. (7) Inlet valves. (8) Lifter. (9) Camshaft. | |
As the camshaft turns, the lobes of the camshaft (9) cause lifters (8) to go up and down. This movement causes the push rods (3) to move the rocker arms (2). The movement of the rocker arms causes the bridge (1) to move up and down. The bridge moves up and down on dowels that are mounted in the cylinder head. Each bridge controls two valves. The bridges open the valves, or the bridges close the valves. There are two intake and two exhaust valves for each cylinder.
Rotocoils (4) cause the valves to turn while the engine is running. The rotation of the valves keeps the deposit of carbon on the valves to a minimum. Fewer deposits of carbon on the valves gives the valves a longer service life.
Valve springs (5) cause the valves to close when the lifters move down.
Turbocharger
The turbochargers are installed at the rear of the exhaust manifolds. All of the exhaust gases from the engine are routed to the turbocharger.
The exhaust gases go through the blades of turbine wheel (5). This causes the turbine wheel and the compressor wheel (2) to turn.
Clean inlet air from the air cleaners is pulled through air inlet (1) of the compressor housing. This air is pulled in by the compressor wheel (2). The compressor wheel causes a compression of the air. The air goes to the inlet manifold of the engine.
 | |
| Illustration 11 | g00590710 |
Turbocharger (1) Air inlet. (2) Compressor wheel. (3) Compressor outlet. (4) Lubrication inlet port. (5) Turbine wheel. (6) Thrust bearing. (7) Shaft bearings. (8) Exhaust outlet. | |
The turbocharger bearings use engine oil under pressure for lubrication. The oil comes in through port (4). This oil goes through passages in order to lubricate the thrust bearing (6), the rings, and the bearings (7). Oil from the turbocharger goes through an opening in the bottom of the center section and to the engine sump.
Balance Line
The balance line controls the correct differential pressure between the line pressure regulator and the carburetor inlet.
When the load on the engine changes, boost pressure from the turbocharger changes in the inlet manifold. The balance line sends a signal of this change in pressure to the spring side of the diaphragm. This diaphragm is in the line pressure regulator. This pressure change causes the regulator diaphragm to move the regulator valve. This movement will correct the gas pressure to the carburetor. This method will ensure the correct differential pressure between the regulator and the carburetor.
Exhaust Bypass For Engines With A Turbocharger
 | |
| Illustration 12 | g00590736 |
 | |
| Illustration 13 | g00590746 |
The exhaust bypass (4) is located on the housing for the exhaust manifold (3). The exhaust bypass controls the amount of exhaust that goes to the turbine wheel. The exhaust bypass valve (9) is activated directly by a pressure differential between the atmospheric air pressure and the turbocharger compressor outlet pressure to the carburetor.
One side of the diaphragm (7) in the regulator feels atmospheric pressure through a breather (11) in the top of the regulator. The other side of the diaphragm feels air pressure from the outlet side of the turbocharger compressor. This air pressure comes from a control line (5). The control line is connected at the connection point (6). When outlet pressure to the carburetor reaches the correct value, the force of the air pressure on the diaphragm moves the diaphragm. The diaphragm will overcome the force of the spring (8) and atmospheric pressure. The valve opens. The exhaust is kept from passing to the turbine wheel.
The bypass passage is located in the housing for the exhaust manifold. Under constant load conditions, the valve will take a set position. This permits enough exhaust to go to the turbine wheel. This exhaust gas will give the correct air pressure to the carburetor.
The exhaust bypass valve can limit the load that can be carried. If the engine is used at high altitudes, the adjustment screw (12) must be tightened. The locknut (10) must be loosened and tightened once the setting has been made.
Electric Governor
Make reference to 2301A Electric Governor Service Manual, SENR4676 for additional information.
The electric governor system gives precision engine speed control. Engine speed is measured constantly. Necessary corrections are made to the engine fuel setting. These adjustments are made through an actuator that is connected to the fuel system.
The engine speed is felt by a magnetic pickup. This magnetic pickup creates an AC voltage that is sent to the control. The control then sends a DC voltage signal to the actuator. The actuator changes the electrical input from the control to a mechanical output. The mechanical output is connected to the fuel system by a linkage. For example, if the engine speed is more than the speed setting, the control will decrease output and the actuator will move the linkage. This will decrease the fuel to the engine.
Governors
 | |
| Illustration 14 | g00332574 |
Schematic of governor (1) Return spring. (2) Output shaft. (3) Output shaft lever. (4) Strut assembly. (5) Speeder spring. (6) Power piston. (7) Flyweights. (8) Needle valve. (9) Thrust bearing. (10) Pilot valve compensation land. (11) Buffer piston. (12) Pilot valve. (13) Pilot valve bushing. (14) Control ports. (A) Chamber. (B) Chamber. | |
Introduction
The governor can operate as an isochronous governor. This governor uses engine lubrication oil that has been increased to a pressure of 1200 kPa (175 psi). The pressure is increased by a gear type pump that is located in the governor. This pump gives the governor hydramechanical speed control.
Pilot Valve Operation
The governor is driven by the governor drive unit. This unit turns the pilot valve bushing (13). The bushing is turned in the clockwise direction when the bushing is viewed from the drive end of the governor. The pilot valve bushing is connected to a ballhead assembly that is driven by a spring. Flyweights (7) are fastened to the ballhead by pivot pins. Centrifugal force is created by the rotation of the pilot valve bushing. The flyweights pivot outward changing the centrifugal force to axial force. This force presses against speeder spring (5). There is a thrust bearing (9) between the toes of the flyweights and the seat for the speeder spring. Pilot valve (12) is fastened to the seat for the speeder spring. Movement of the pilot valve is controlled by the action of the flyweights against the force of the speeder spring.
When the engine is at governed rpm, the axial force of the flyweights is equal to the force of compression in the speeder spring. The flyweights will be in the position that is shown. Control ports (14) will be closed by the pilot valve.
Increase In Fuel
When the operator desires an increase in rpm, the speeder spring will increase. If the load on the engine increases, the axial force of the flyweights decreases. The force of compression in the speeder spring may increase. The axial force of the flyweights may decrease. The pilot valve will always move in the direction of the drive unit. This opens control ports (14). Pressurized oil flows through a passage in the base to chamber (B). The increased pressure in chamber (B) causes power piston (6) to move. The power piston pushes strut (3). The action of the output shaft lever causes counterclockwise rotation of output shaft (2). This moves the control linkage (15) for the carburetor. This control linkage moves to the OPEN THROTTLE position.
 | |
| Illustration 15 | g00590781 |
Governor (2) Output shaft. (15) Control linkage. | |
As the power piston moves in the direction of return spring (1) the volume of chamber (A) increases. The pressure in chamber (A ) decreases. This pulls the oil from the chamber inside the power piston. The oil continues above the buffer piston (11) into chamber (A). The buffer piston moves upward in the bore of the power piston. Chamber (A) and chamber (B) are connected to the chambers that are above and below the pilot valve compensation land (10). The pressure difference that is felt by the pilot valve compensation land adds to the axial force of the flyweights. This force moves the pilot valve upward. This action closes the control port. When the flow of pressure oil to chamber (B) stops, the movement of the fuel control linkage stops as well.
Decrease In Fuel
When the force of compression in the speeder spring decreases, or the axial force of the flyweights increases, the pilot valve will move in the direction of the speeder spring (5). This opens control ports (14). Oil from chamber (B) and pressurized oil from the pump will dump through the end of the pilot valve bushing. The decrease in pressure in chamber (B) will allow the power piston to move in the direction of the drive unit. The return spring (1) will push on the strut assembly (4). This moves the output shaft lever (3). The action of the output shaft lever causes the clockwise rotation of the output shaft (2). This moves the control linkage (15) for the carburetor in the CLOSED THROTTLE direction.
Speed Adjustment
On governors that are not equipped with electric speed adjustment, the speed can be adjusted manually. The shaft of the linkage assembly (2) will push on the speeder spring (3). This causes an increase in the force of the speeder spring and pilot valve (4) will move toward the governor drive unit. Make reference to the Pilot Valve Operation section of this text. The engine will increase in speed until the desired rpm is reached. When the shaft of the linkage assembly is turned counterclockwise, the link assembly moves away from the speeder spring and the pilot valve will move away from the governor drive unit. The engine will decrease in speed until the desired rpm is reached.
 | |
| Illustration 16 | g00639050 |
Nonelectric PSG governor (1) Screw. (2) Link assembly. (3) Speeder Spring. (4) Pilot valve. | |
Governors that are not electric are equipped with manual governor control.
 | |
| Illustration 17 | g00590787 |
Governor Control (5) Positive Lock lever. (6) Lever. (7) Governor. | |
As the lever (6) is moved to the governor (8), the linkage causes the lever (7) to move in the same direction. Lever (7) is clamped to the shaft of link assembly (2). When the shaft rotates, the linkage assembly (2) will push on the speeder spring (3). This causes pilot valve (4) to move toward the governor drive unit. Make reference to the Pilot Valve Operation portion of this text for additional information. The engine will increase in speed until the desired rpm is reached.
When lever (6) is moved away from the governor, lever (7) moves in the same direction. This causes the link assembly to move away from the speeder spring. The pilot valve moves away from the governor drive unit. Engine speed decreases until the desired rpm is reached.
 | |
| Illustration 18 | g00596805 |
PSG Electric Governor (8) Synchronizing motor. (9) Clutch assembly. (10) Link assembly. | |
On electric governors, speed adjustments are made by a DC reversible synchronizing motor (9). This motor is a 24 volt motor. This motor is controlled by a switch that can be put in a remote location.
The synchronizing motor drives the clutch assembly (10). The clutch assembly protects the motor from being run against the adjustment stops.
When the clutch assembly is turned clockwise, the linkage assembly (11) will push on the speeder spring. The force of compression in the speeder spring is increased. This causes the pilot valve to move toward the governor drive unit. Refer to the Pilot Valve Operation portion of this text for more information. The engine will increase in speed. This increase in speed will allow the engine to reach a stable rpm.
When the clutch assembly is turned counterclockwise, the link assembly moves away from the speeder spring. The force of compression in the speeder spring is decreased. This causes the pilot valve to move away from the governor drive unit. The engine will decrease in speed. This will allow the engine to reach a stable rpm.
Note: The clutch assembly can be turned manually if it is necessary.
Speed Droop
 | |
| Illustration 19 | g00596826 |
PSG Governor (11) Link assembly. (12) Pivot pin. (13) Output shafts. (14) Adjusting bracket. (15) Shaft assembly. | |
This governor has adjustable speed droop. The governor is isochronous when the no-load rpm and the full load rpm are equal. The load can be divided between two or more engines that drive generators connected to a single shaft.
When the pivot pin is put in alignment with output shafts (13), movement of the output shaft lever will not change the force of the speeder spring. When the force of the speeder spring is kept constant, the desired rpm will be kept constant. Make reference to the Pivot Valve Operation section of this text for more information. The pivot pin can move out of alignment with the output shafts. This will cause the output shaft lever to move. The force on the speeder spring will change proportionally with the load on the engine. When the force of the speeder spring is changed, the desired rpm of the engine will change.
A bracket for adjustments (14) is located outside of the governor. This bracket is connected to the pivot pin (12). These parts are connected by the link assembly (11) and the shaft assembly (15) .