ARMY TM 9-6115-670-14&P
1-22
1.18. CONTROL OPERATION.
1.18.1 Engine Speed Control System. A magnetic speed sensor (Figure 1-10) is installed on the
engine block facing the teeth of the flywheel. As the flywheel rotates, it creates a magnetic field in the
sensor. The frequency of the magnetic field varies with engine speed and is fed to the speed control
box. If the signal indicates that the engine is varying from the specified 3600 rpm, the control box senses
the incorrect frequency and sends a 24 VDC signal to an actuator/solenoid. The solenoid operates an
actuator linkage which is connected through a pivot arm to a stud on the engine governor. Movement of
the linkage rotates the governor arm which adjusts engine speed. When the sensor signals that correct
engine speed is achieved, the control box cuts off its signal to the actuator/solenoid.
Figure 1-10. Engine Speed Control System
