The engine speed is detected by an engine speed sensor (magnetic pickup) that is installed in the flywheel housing. The sensor generates AC voltage that is sent to the governor. The governor sends DC voltage to an actuator. The actuator converts the electrical input into a mechanical output. The actuator moves the linkage that is connected to the throttle plate in order to adjust the engine speed.
If the engine speed is greater than the speed setting, the governor reduces the output to the actuator. If the engine speed is less than the speed setting, the governor increases the output to the actuator.
For detailed information on electronic governors, refer to the appropriate publication for your equipment:
Pressure Compensated Simple Governor (PSG)
The basic PSG is a hydromechanical governor. The governor's hydraulic pressure is provided by engine oil. The operation is normally isochronous. Unless the load is changing, the engine speed is maintained regardless of the load.
For detailed information on the governor, refer to Installation, Operation, and Maintenance, SENR6514, "PSG Governor with Cast Iron Case".
The ProAct actuator is an electronic actuator. The throttle plate is driven directly by the actuator. Input to the actuator is provided by the ProAct Digital Speed Control. Adjustments to the actuator are performed with a hand held programmer.
The EG-3P Actuator is a hydraulic actuator. The actuator's hydraulic pressure is provided by engine oil. An electronic governor sends a signal to the actuator. The actuator converts the electronic signal into hydraulic pressure. The hydraulic pressure moves the mechanical linkage that is attached to the throttle plate.