单项选择题
Overflow valve is used to （）
A.control the fluid flow through it B.prevent the pressure before it over the specified valve C.make the pressure after it steady D.control the direction of oil flow
单项选择题 Hydraulic control check value is generally used to （） in the marine hydraulic mechanism.
单项选择题 Check value is used to control （）
单项选择题 （）can cause oil flow from sludge outlet of self cleaning separator.
