BELT-SERPENTINE 7E4841 - Caterpillar

Illustration 1 g00854634
The standby pump panel has six identical circuits. Each circuit consists of the following components: enable input, contactor input and relay. Each pressure contactor monitors the pressure in the contactor's system. The following circuits are enabled 9 seconds after the engine reaches crank termination speed:
The auxiliary circuit for low oil pressure at a low speed
The auxiliary circuit for low fuel pressure
The auxiliary circuit for low jacket water pressure
The auxiliary circuit for low aftercooler / oil cooler water pressure
The auxiliary circuit for low sea water pressureCrank termination speed is reached when the engine is running and the starter motor is disabled.A signal (+24 DCV) enables the circuits that are listed above. The signal is sent from terminal 91 in the panel for the control system to terminal 491 in the standby pump panel. The auxiliary circuits remain enabled for 2 seconds after the engine has stopped. The auxiliary circuit for low oil pressure at high speed is enabled 9 seconds after the engine rpm rises above the oil step speed. This contactor is disabled immediately when the engine rpm falls below the oil step speed. This circuit is enabled by a signal (+24 DCV) from terminal 93 in the panel for the control system. Terminal 93 is connected to terminal 493 in the standby pump panel.When the pressure falls below the setting for an individual contactor, the normally closed contact of the CONTACTOR will close. The associated relay will then energize. When the associated relay energizes, the normally open contact of the RELAY will close. This sends an auto start signal to the associated start/stop circuit of the proper standby pump. Another normally open contact will close in order to keep the associated relay energized until the circuit that is enabled is disabled. For the following contactors, the circuit is disabled when the engine speed falls to 0 rpm (+2 seconds):
The contactor for low oil pressure at low speed
The contactor for low fuel pressure
The contactor for low jacket water pressure
The contactor for low after cooler / oil cooler water pressure
The contactor for low sea water pressureThe low oil pressure contactor for high speed is disabled when engine speed falls below the oil step speed.