LOCKNUT-SPECIAL 1195198 - Caterpillar

Crankcase Pressure Contactor
Illustration 1 g00865679
(1) Crankcase pressure contactor in the monitor panel (2) HoseCrankcase pressure contactor (1) is located in the monitor panel on the left rear side of the engine.The special crankcase pressure contactor activates at a very low pressure. Hose (2) is routed from the contactor to a port in the side of the cylinder block in order for the contactor to monitor the engine's crankcase pressure. If the pressure becomes 1 kPa (4 inches of H2O) greater than the ambient air pressure, the contactor generates a shutdown signal.Hose (2) must have a constant downward slope in order to drain the fine droplets of engine oil that enter the hose. Otherwise, the engine oil could stop the crankcase pressure from reaching the contactor.Contactors for Low Engine Oil Pressure
Illustration 2 g00865722
Contactors for low engine oil pressureThe engine has two contactors which provide two-step protection from low engine oil pressure. Both contactors can generate shutdowns for low engine oil pressure. One contactor provides protection during operation at slower speeds and the other contactor provides protection during operation at faster speeds.Neither of the contactors are enabled during cranking. A nine second delay allows the engine oil pressure to rise during start-up. Otherwise, the start-up would be inhibited due to low engine oil pressure.Crank terminate relay - During start-up, this normally open contact is closed after the engine reaches 165 rpm. The closed contact indicates that the engine is running. The contact remains closed during engine operation. The contact opens after the engine rpm is zero for two seconds.At nine seconds after the crank terminate speed is achieved, the contactor for low engine oil pressure at low engine speed is enabled. This contactor provides protection against low engine oil pressure until the engine's oil step speed is achieved.Engine's oil step speed - The engine oil pressure increases when the engine rpm increases. The engine's oil step speed is 75 percent of the rated speed. The engine's oil step speed determines the contactor that is enabled to provide protection from low engine oil pressure.At nine seconds after the engine's oil step speed is achieved, the contactor for low engine oil pressure at high engine speed is enabled. The contactor is enabled until the engine speed is reduced to less than 75 percent of the rated speed.Both of the contactors have different pressure settings in order to activate switches at certain engine oil pressures. If the engine oil pressure is reduced to the corresponding setting, a shutdown is activated.The settings have a hysteresis of approximately 15 to 30 kPa (2.4 to 4.4 psi). If either contactor is activated by low engine oil pressure, the contactor remains activated until the engine oil pressure rises to 15 to 30 kPa (2.4 to 4.4 psi) more than the setting.