In hydraulic transmission system, the commonly used to control the direction of the oil is
A. throttle valves
B. speed regulaing valves
C. relief va;ves
D. directional control valves
When a two-position, five-way directional control valve is at any position, how many oil ports on the valve core?
A. 2
B. 3
C. 4
D. 5
___________________allow several actuator notions to obey the setting scheduled actions in turn.
位于顶枕沟与距状沟之间的为
A. 楔前叶
B. 楔叶
C. 舌回
D. 中央旁小叶
E. 扣带回