轮机英语船舶辅助机械单项选择题每日一练(2018.08.03)

单项选择题
If the suction pressure at the refrigeration compressor is below normal, the cause can be（）.
A.refrigerant overcharge
B.overfeeding by the expansion valve
C.a restricted suction strainer
D.due to short cycling of the compressor
单项选择题
If a centrifugal bilge pump were continually operated with the discharge valve closed the （）.
A.motor overload would open
B.relief valve would open
C.pump would eventually overheat
D.motor would overheat
单项选择题
In a general cargo crane, three principal movements are （）；（）；（）.
A.hoisting；luffing；slewing
B.lifting；raising；lowering
C.rotating；raising；handling
D.hosting；lowering；moving
单项选择题
During working, thermostatic expansion valve should be （）.
A.either all the way open or all the way closed
B.normally fully open
C.throttled depending on load
D.controlled by liquefied pressure
单项选择题
Which of the valves listed is NOT considered to be a hydraulic system directional control valve?（）
A.Spring-centered valve
B.Unloading valve
C.Three-position valve
D.Two-position valve