Basic Knowledge About Engine

1. When the external load decreases, the diesel engine speed increases beyond the specified range. What possible faults exist in the speed governor?

 Answer: When the external load decreases, and the diesel engine speed increases beyond the specified range, the speed governor may experience the following faults:

1) There is a jamming in the fuel regulation linkage between the governor and the injection pump. When the external load decreases, the fuel injection quantity cannot be reduced.

2) The governor spring preload is too high, or the fuel injection pump has a positive fuel supply value when adjusted to the "zero position," increasing the fuel supply quantity.

3) The governor is not properly adjusted.

2. Why does the governor sometimes fail to make the diesel engine run at full speed?

Answer: The reasons why the governor may fail to make the diesel engine run at full speed include:

1) Due to excessive clearance in the fuel regulation linkage between the governor and the injection pump, a free-moving phenomenon occurs, or the fuel injection pump has a large negative value when adjusted to the "zero position." 1) When the governor's output shaft has reached its maximum fuel supply, the fuel injection pump has not yet reached the corresponding fuel supply, so the diesel engine cannot reach full speed.

2) Insufficient preload of the governor's spring adjustment causes the centrifugal force generated by the governor's weight to balance the spring tension before the diesel engine reaches full speed, thus limiting the fuel supply to the diesel engine. Therefore, the governor cannot make the diesel engine run at full speed.

3. What are the main reasons for unsatisfactory speed fluctuations in the governor or abnormal oscillations in the fuel regulation linkage?

Answer: The main reasons for unsatisfactory speed fluctuations in the governor or abnormal oscillations in the fuel regulation linkage are:

1) The governor or fuel regulation linkage is stuck, causing a sudden increase or decrease in speed. In this case, the fuel level in the fuel regulator and governor should be checked. Checking for governor sticking can only be done when the engine is stopped and the governor and fuel regulator are disengaged. Governor sticking is usually caused by contaminated or increased viscosity of the fuel.

2) Excessive clearance or loose connecting rods in the fuel regulation linkage between the governor and the injection pump can cause severe speed fluctuations during governor operation, resulting in inconsistent machine speed. In this case, the fuel regulation linkage should be inspected.

3) Irregular transmission from the diesel engine to the governor can cause abnormal, continuous oscillations in the fuel regulation linkage. The meshing of the drive gears in the governor should be checked.

4) Improper governor adjustment. For example, excessively large adjustment of the hydraulic governor's compensation pointer can cause excessive speed variations. Additionally, excessively large needle valve opening or excessive static speed difference (speed drop) adjustment can also cause speed fluctuations and abnormal, continuous oscillations in the fuel regulation linkage. The compensation mechanism should be inspected and readjusted.