The desired engine speed is determined by several factors. The Caterpillar Electronic Technician (ET) is used to program these parameters that affect the governing: "Low Idle Speed", "Minimum Engine High Idle Speed", and "Maximum Engine High Idle Speed". The programmable "Engine Accel. Rate" determines the rate of acceleration and of deceleration.
The "Governor Type Setting" parameter can be set to "Isochronous Mode".
The "Governor (Proportional) Gain Percentage" and the "Governor (Integral) Stability Percentage" can be adjusted for additional control of the throttle actuator.
An input of either 0 to 5 VDC or 4 to 20 mA can provide the programmable "Desired Speed Input Configuration". This input can be provided by a potentiometer, a load sharing unit, or a programmable logic controller.
During engine operation, the actual engine speed is detected via a signal from the engine speed/timing sensor. The ECM compares the actual engine speed to the desired engine speed. The ECM controls the throttle to match the actual engine speed to the desired engine speed. This is a continuous process.
There is no feedback for the throttle position. The ECM issues a throttle command that represents a percent of the position. The output can be viewed on Cat ET. The actual throttle position can be viewed on a mechanical pointer that is built into the mechanism of the throttle.