Section III. PRINCIPLES OF OPERATION

TM 9-6115-668-13 Section III. PRINCIPLES OF OPERATION 1.13 GENERAL DESCRIPTION. 1.13.1 Diesel Engine. The engine is an 8-cylinder diesel engine with exhaust-driven turbochargers, direct fuel injection, elec- tronic speed control, and an electro-hydraulic fan (figure 1-4). In the speed control system, the speed pick-up detects actual engine speed at the flywheel toothed ring. That value is sent to speed governor assembly N1, which compares actual engine speed to the adjust- able engine speed setpoint. If there is a discrepancy, N1 sends a control signal to the speed control de- vice. The speed control device converts the control signal to a rotary motion that acts on the fuel injection pump through a linkage. The engine speed setpoint, and therefore the generator frequency, are adjusted with the FREQUENCY ADJUST potentiometer (R4). If the load changes, digital isochronous load sharing module N4 generates, from the current changes de- tected by T2 to T4, a control signal that is superimposed on the voltage (engine speed setpoint) picked off from the FRQUENCY ADJUST potentiometer (R4). N1 and the speed control device thus counteract any decrease in engine speed caused by increased load, or any increase in engine speed resulting from a load falloff. Speed governor assembly N1, which has a slower control response, then performs fine ad- justments. The diesel engine is cooled by an electro-hydraulic fan (EHG). To achieve temperature-dependent speed regulation of the EHG, the engine oil and cylinder head temperatures are sensed by temperature-depen- dent resistors (1830.1 at cylinder 6 and 1B30.2 at cylinder 1). These are connected to EHG controller N7, which controls solenoid valve 1Y11. The solenoid valve modifies the volume of oil flowing through the EHG (and therefore the fan rotation speed) as a function of temperature. The pressure and temperature of the diesel engine oil are determined by sensors, and displayed on the OIL PRESSURE (P9) and OIL TEMPERATURE (P10) meters. If values go above or below the allowable range, pressure and temperature sensitive switches close and shut down the Generator Set 150 kW. Faults are indicated by the OIL PRESSURE (H3) and OIL TEMP-CYLINDER HEAD (H4) lamps. All electrical cables to the fuel tank assembly and the diesel engine (except the shielded cables to the control device and the pick-up) pass through the filter box (FK) for filtration and interference suppression. The low-pass filters dissipate HF voltages to ground, and the varistors suppress voltage spikes. 1.13.2 Fuel Tank Assembly. The tank can be filled with a fueling nozzle, a canister, or the electric fuel pump. The fuel pump is turned on with the FUEL TANK PUMP ON illuminated pushbutton switch (S19), and shut down with the FUEL TANK PUMP OFF pushbutton switch (S18). The maximum tank level switch automatically shuts off the fuel pump at maximum tank capacity. The fuel level sensor delivers a tank level signal that is displayed on the FUEL LEVEL meter (P11). The minimum tank level switch delivers a signal indicating that two hours of operating time remain. The LOW FUEL lamp (H15) lights up when this level is reached. The alarm signal is applied to PAR- ALLEL OPERATION receptacle J9, and sent via the EPP III to the ECS. 1 - 1 5