In the large flow hydraulic system, what type of directional control valve should be used? ()
A. electromagnetic
B. electro-hydraulic
C. manual
D. mechanical
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When overflow exists in the fixed pressure relief valve, it can maintained____ stable. ()
A. inlet pressure of the valve
B. outlet pressure of the valve
C. inlet and outlet pressure of the pump
D. the actual flow of the pump
The speed regulating valve is made of ().
A. throttle valve and constant pressure reducing valve in series
B. throttle valve and sequence valve in series
C. throttle valve and constant pressure reducing valve in parallel
D. throttle valve and sequence valve in parallel
If a three-position directional control valve is workin in center position, the pressure oil is connected with the two chambers of cylinder, and the return oil is closed, then the center function of the valve is ________ type. ()
A. P
B. Y
C. K
D. C
Compared with throttle valve, the remarkable characteristics of speed regulating valve are ().
A. good flow stability
B. simple structure and low cost
C. large adjustment range
D. limit of minimum pressure difference is small