单项选择题
A.varying the pump discharge pressure
B.varying the pump return pressure
C.rotation of the pump plunger
D.rotation of the pump barrel
单项选择题 On a diesel engine equipped with a hydraulic speed control governor, hunting in many cases can be corrected by adjusting the （）
单项选择题 Which of the following adjustments is always required whenever the diesel engine governor oil has been drained and renewed?（）
单项选择题 Which of the following statements represents an advantage of an electromagnetic clutch?（）