A.contraction
B.retraction
C.expansion
D.shrinkage
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A.Hydraulic pumps
B.Valves
C.Hydraulic cylinders
D.Hydraulic motors
A.the slewing motor
B.the luffing motor
C.the hoisting motor
D.none of the above
A.unusual vibration
B.excessive worn parts
C.abnormal pressure
D.any of the above
A.Relief valve
B.Direction control valve
C.Stop valve
D.Pressure control valve
A.flow of oil
B.pressure of oil
C.A and B
D.temperature of oil
最新試題
The usual symptoms of cavitation in a centrifugal pump is （）.
Which of the listed pumps is NOT a positive displacement pump?（）
If the head pressure of a reciprocating refrigeration compressor is excessive, （）.
Which of the following problems could cause the high pressure cutout switch to shut down the compressor in a refrigeration system?（）
The major source of chemical contaminants in hydraulic fluid is （）.
Which of the problems listed would came the discharge temperature of an R-12 refrigeration compressor to increase?（）
Pitting in the suction areas of a centrifugal pump bronze impeller is usually caused by （）.
The temperature differential occurring between the inlet temperature of the fluid to be cooled and the outlet temperature of the cooling medium in a shell-and-tube heat exchanger is greatest in which of the flow designs listed?（）
The general purpose of a heat exchanger is to （）.
If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will （）.