3-3.1 DIESEL ENGINE. The engine is a four-cycle, internal combustion engine that includes an intake air cleaner/silencer, six pistons and connecting rod assemblies, a crankshaft assembly, idler gear, camshaft assembly, cylinder head assembly, cylinder block assembly, and an accessory drive assembly. The piston and connecting rod assemblies convert the heat energy released by fuel combustion into mechanical energy to rotate the crank- shaft assembly. Crankshaft assembly rotation is then transmitted by the idler gear to the camshaft assemblies through a gear train. The camshaft assemblies actuate the cylinder head assemblies to inject fuel into and con- duct exhaust gases out of the cylinders in the required timed sequence. The cylinder head assembly forms the top enclosure for the cylinders and provides for cooling, lubrication, fuel injection, and exhaust gas removal. (The model 6BT5.9-M includes a turbocharger to increase intake air volume and pressure.) The cylinder block assem- bly supports and aligns the diesel engine components and provides internal passages for oil, coolant, and air flow. Various diesel and non-diesel accessory equipment is driven by the accessory drive assembly.
3-3.2 ELECTRICAL STARTING SYSTEM. The electrical starting system includes a starting circuit, 24-volt battery bank, starting motor, and an alternator. A deposition toggle switch (OFF, RUN, START) is included for engine control. The OFF position closes the fuel supply to the injection pump. The RUN position energizes the engine gauges, instruments, warning lights, and control devices, and also opens the fuel supply valve. The START position is a momentary contact. When held closed, the solenoid switch on the starter motor is closed to supply full battery power to the starter motor for cranking the engine. When released the switch returns to the RUN position where it remains until it is moved to the OFF position. An electrical interlock, which is included in the engine throttle and clutch control, prevents starting the engine unless the transmission is in neutral.
The alternator includes a solid-state, integral voltage regulator. A positive battery lead supplies power for ini- tial excitation of the alternator field. An alternator failure warning light is fed by the same line. As soon as the alternator begins to generate voltage, that voltage matches the battery voltage to the regulator and turns out the alternator failure warning light, and the alternator becomes self-excited. The voltage regulator senses battery con- dition and maintains alternator output voltage at an appropriate level throughout the full range of engine running speeds. When the alternator output stops, battery power returns to the warning light.
3-3.3 AIR INTAKE AND EXHAUST SYSTEMS.
3-3.3.1 Air Intake System. The air intake system provides clean air to the cylinders at atmospheric pressure for the model 6135.9-M, and above atmospheric pressure for the model 6BT5.9-M. The model 6B5.9-M intake sys- tem includes air cleaner/ silencer piping and an intake manifold and intake valves, through which clean, cool air is admitted into the engine cylinders. The model 6BT5.9-M is equipped with an exhaust-driven turbocharger, which increases the intake air volume and pressure to the cylinders via the intake manifold and intake valves. S9233-C9-MMA-010
Figure 3-1. Electrical Schematic (Sheet 1 of 2)
3-4
Figure 3-1. Electrical Schematic (Sheet 2 of 2)
3-6
3-3.3.2 Exhaust System. The exhaust system includes those components used to expel the engine’s exhaust gasses. It starts with the exhaust valves, one valve for each of the six cylinders. Each cylinder expels its exhaust gas into the manifold: in the model 6B5.9-M, the exhaust passes through a sea water-cooled exhaust elbow fit- ting, through a 2-1/2-inch to 3-inch piping, a muffler, and more piping to the atmosphere. The path of the exhaust gasses for the model 6BT5.9-M is the same from the cylinder exhaust valve to the exhaust manifold, but in this model, the exhaust gasses are used to drive the turbocharger. From the turbocharger, the exhaust gas passes through the sea water-cooled elbow, piping, muffler, and additional piping before it is discharged to the atmo- sphere.
3-3.4 FUEL SYSTEM. The fuel system consists of a fuel lift pump, injection pump, fuel drain manifold, throttle, shutoff valve, fuel injection nozzles, and fuel lines.
3-3.4.1 Fuel Pumps. The fuel lift pump is attached to the side of the engine block. The lift pump pulls fuel from the supply tank and supplies low-pressure fuel (3 to 5 psi) to the fuel filter head, through the filter, then to the fuel injection pump. The fuel injection pump increases fuel pressure and routes the high-pressure fuel to each Injection nozzle.
3-3.4.2 Fuel Injection Nozzles. Fuel is supplied through the high-pressure lines to the fuel injection nozzles in the cylinder head. When the high-pressure fuel reaches the injection nozzles, the pressure lifts the needle valve against spring tension and allows fuel to enter the combustion chamber. A common drain line returns unused fuel to the supply tank.
3-3.4.3 Fuel Drain Manifold. Any leakage past the fuel injection needle valve enters the fuel drain manifold. The fuel drain manifold routes controlled venting from the injection pump and leakage from the nozzles back to the main fuel tank.
3-3.4.4 Throttle. The throttle provides a means for the operator to manually control engine speed above idle, as required, by varying operating conditions of speed and load.
3-3.4.5 Fuel Shutoff Valve. The injection pump is equipped with an electrical shutoff valve. This solenoid- operated valve blocks the supply of fuel to the high-pressure pumping and distribution components. The valve is designed to be closed when there is no electrical power to the solenoid.
3-3.5 LUBRICATION SYSTEM. The engine is pressure-lubricated by a gerotor-type lube oil pump driven by the front crankshaft gear located in the oil pan at the front of the engine. A pressure regulator is mounted in the block to control pressure. Filters and screens are provided in the lubricating system to remove impurities in the oil. A bypass valve is provided in the full-flow oil filter head to continue lubrication if the element becomes clogged. The engines lube oil capacity at full level holds 15 quarts of oil.
3-3.6 COOLING WATER SYSTEMS.
3-3.6.1 Fresh Water Cooling System. Coolant in the fresh water cooling system consists of a mixture of fresh water and antifreeze. The engine fresh water cooling system includes an engine block, cylinder head, heat exchanger, fresh water pump, thermostat, expansion tank, and piping; it has a coolant capacity of 21.8 gallons. The coolant is pressurized up to 15 pounds psi when the diesel engine is running at normal operating speed (2500 rpm) by the fresh water pump. Coolant output from the fresh water pump empties into the oil cooler cavity of
the cylinder block. The coolant circulates around each cylinder and crosses the cylinder block to the fuel injec- tion pump side of the engine. As the coolant flows through the cylinder head and block toward the thermostat, it provides cooling for the fuel injection nozzles. When the engine is below operating temperature, the thermo- stat is closed and coolant flow bypasses the heat exchanger, trapped air goes to the water pump inlet via drilled passages in the block and head. When the operating temperature is reached, the thermostat opens, thereby block- ing the bypass passage to the fresh water pump and opening the outlet to the heat exchanger. Coolant flowing through the heat exchanger to the fresh water pump is cooled by a counterflow of sea water pumped through the heat exchanger. Sea water exits from the heat exchanger via a sea water connection at the upper rear end of the heat exchanger. The expansion tank provides make-up coolant for the closed coolant system and provides a place for hot coolant to expand.
3-3.6.2 Sea Water Cooling System. The sea water cooling system furnishes sea water, which is used to cool oil passing through the transmission’s oil cooler, fresh water coolant passing through the heat exchanger, and exhaust gas passing through the exhaust manifold elbow to the muffler. The water pump, which has a maximum suction lift of 10 feet, draws sea water through a strainer with a minimum open area of six square inches. The sea water pump discharges coolant at a maximum pressure of 15 psi.
3-3.7 CONTROLS AND INDICATORS. Various controls and indicators are provided with the diesel engine installation to start, operate, and shut down the diesel engine and to monitor diesel engine parameters during operation. Seefigure 3-1for an electrical schematic of the engine controls.
3-3.7.1 Starter Switch. When the starter switch is activated, 24-Vdc is supplied to the solenoid, completing the circuit to the starter motor on the engine.
3-3.7.2 Electrical Fuel Shutoff. The fuel shutoff is installed on the fuel injection pump. Its purpose is to stop the engine under normal operating conditions by stopping the fuel flow to the nozzles when the start switch is moved to the OFF position.
3-3.7.3 Tachometer. The tachometer is electrically connected to a sender attached to the engine. It converts mechanical motion to electrical impulses to cause the tachometer to indicate engine speed (rpm).
3-3.7.4 Lube Oil Pressure Switch. The lube oil pressure switch is a break-type switch set to actuate when the lube oil pressure drops to eight psi. This completes the low lube oil alarm circuit to the control panel to activate the engine warning light. The switch is located on the fuel pump side of the block.
3-3.7.5 Water Temperature Switch. The water temperature switch, which is located on the cylinder head, is operated by a high cooling water temperature condition. When the cooling water temperature exceeds 225°F, the switch closes a set of contacts that causes the engine warning light at the control panel to activate.
S9233-C9-MMA-010
CHAPTER 4
SCHEDULED MAINTENANCE