Diesel generator governor's role is to limit the engine speed within a certain range. Runtime engine load is carried constantly changing. When the load changes, especially sudden changes, must remain stable speed diesel engines, with no parking or coaster accident. Speed governor is automatically maintained stable devices. For diesel engines for power generation, requiring substantially constant speed synchronous speed, the governor characteristics governor demanding.

When the internal combustion engine, such as the internal combustion engine output torque and external resistance moment (load) are equal, working to stabilize. If the drag torque exceeds the torque of the engine, the speed will be reduced; otherwise increased. To make the work mechanically stable work, you must change the resistance of the fuel supply adjusted accordingly, so that the engine's torque load to adapt to the outside world. As can be seen from the characteristics of the diesel engine speed, engine torque Me = f (n) curve is relatively flat. When the diesel engine running, such as fuel adjustment lever in a fixed position, engine speed torque characteristics by Me on change, and external load is constantly changing. In the wet and dry as bulldozers different soils of varying hardness when jobs resistance moment there is a significant change. If there are small changes in the resistance torque (△ M), will cause large changes in the rotational speed (△ n), the work of the engine is unstable. To control the supply amount of the artificial changes to adapt to the external load, which not only allows the driver fatigue, but also difficult to maintain stable rotation.

Governor belongs automatic adjustment device. When the external load changes, it can automatically adjust with changes in the load amount of oil, so that the engine speed is stable within a certain speed range.

Automotive or construction machinery is often working under changing load conditions, but also the load encountered mutations. When operations such as bulldozers, dump later when, due to a sudden shed load, fuel pump fuel adjustment lever for a moment, a chance to move in the direction to reduce the amount of oil, the engine speed will be increased rapidly, but this time due to the injection pump the role of speed characteristics, fuel injection pump cycle instead of increasing, prompting further increase the speed of the diesel engine. Such interactions result, they increasingly high speed diesel engine, there will be serious speeding, or even "speed" accident that caused mechanical damage.

In addition, the diesel engine is also often encountered low idle (idle) applications, such as short-term parking, warm start the car, the transmission shift and so on. When the diesel engine is only idling fuel supply amount of the small, this part of the energy emitted by the fuel inside the engine friction can be overcome, then the operation of the engine depends on the stability of the change in the internal cylinder and the gas acting friction changes interrelationships. Both are available pressure Pm average mechanical losses and changes in mean indicated pressure Pi is represented. The increase in general with the speed of the engine, the average pressure Pm mechanical losses are increased slightly. In order to stabilize idling must when speed increases, the mean indicated pressure Pi decreases, while it increases when the speed is reduced. When the diesel engine idling, fuel adjustment lever to maintain a minimum amount of oil in the position, then if for some reason (such as lubricating oil viscosity changes) diesel internal resistance increases slightly, its speed will slightly lower, but due to the the role of the injection pump speed characteristics, however, reduced the amount of fuel per cycle, which prompted further reduce the speed迸, and so the role of engine flameout finally make; Conversely, if the diesel internal resistance decreases slightly, it will lead to engine idling speed rising, so idling diesel engine is very unstable. Therefore, the car engine is usually installed to prevent speeding and stability to achieve the purpose of idling with bipolar governor.

That is the role of the governor is to change the course of the change curve Pi, Pi curve makes with the speed increases dramatically. Such stability can be maintained at idle, can be prevented at high speed.

In some special operating conditions of the engine, such as a sudden load change working machinery in the working conditions and the change of load to maintain a certain range of engine speed (e.g., with generators, air compressors, pumps, etc.), the required Converter with full program, which can prevent overspeed governor is not only at idle and stability at any speed but also the automatic control required condition. Full program can also reduce the governor drivers to operate and improve the use of economic and labor productivity diesel engines.

Speed characteristics plunger injection pump. Fuel injection pump cycle depends primarily on the amount of fuel adjustment rod (rod or gear lever) position. However, in fact, is also affected by the amount of fuel the engine speed.

When the fuel lever position timing loop fuel injection pump fuel supply relationship with the speed changes, called the fuel pump speed characteristics. Work it has a great impact on the diesel engine.