[M.D. Holloway]

and

The governors, used on heavy-duty truck applications and construction equipment, fall into one of two basic categories:
• Limiting-speed governors, sometimes referred to as minimum/maximum models since they are intended to control the idle and maximum speed settings of the engine. Normally there is no governor control in the intermediate range, being regulated by the position of the throttle linkage.
• Variable-speed or all range governors that are designed to control the speed of the engine regardless of the throttle setting.
Other types of governors used on diesel engines are as follows:
1. Constant-speed, intended to maintain the engine at a single speed from no load to full load.
2. Load limiting, to limit the load applied to the engine at any given speed. Prevents overloading the engine at whatever speed it may be running.
3. Load-control, used for adjusting to the amount of load applied at the engine to suit the speed at which it is set to run.
4. Pressure regulating, used on an engine driving a pump to maintain a constant inlet or outlet pressure on the pump.
At this time on heavy-duty truck and construction equipment applications, straight mechanically designed units dominate the governor used on nonelectronic fuel injection systems.