轮机英语船舶辅助机械单项选择题每日一练(2019.01.12)

单项选择题
For occasional heavy loads, two cranes can be arranged to work together. The operating （） for deck crane motors may be hydraulic electric.
A.principle
B.medium
C.instruction
D.voltage
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
单项选择题
External and internal leakage in hydraulic systems may be caused by （）.
A.unusual vibration
B.excessive worn parts
C.abnormal pressure
D.any of the above
单项选择题
Which of the following is operated from the main engine room console on an automated vessel?（）
A.Fire pump and lube oil pump
B.Lube oil pump and distilling plant
C.Distilling plant and shaft alley door
D.Shaft alley door and fixed CO2 release
单项选择题
The shaft and spare parts（） should be well greased in order to avoid corrosion.
A.in the store room
B.in the cylinder
C.in the scavenge air box
D.in the water box