A.the slewing motor
B.the luffing motor
C.the hoisting motor
D.none of the above
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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
A.Relief valves
B.Check valves
C.Safety valves
D.Reducing valve
A.Hydraulic pumps
B.Valve
C.Hydraulic cylinders
D.Hydraulic motors
最新試題
One cause of high head pressure occurring in a refrigeration system can be （）.
The control mode in which the final control element is moved from one of two flexed positions to the other is known as （）.
When the steering gear is in operation, you should （）.
The general purpose of a heat exchanger is to （）.
An excessive charge of refrigerant in an air-cooled refrigeration system can cause （）.
Low compressor head pressure in a refrigeration system can be caused by（）.
The rate of heat transfer between the hot and cold fluids passing through a shell-and-tube type heat exchanger will （）.
Thermostatic expansion valves can be adjusted for （）.
An increasing head pressure in a refrigeration system, without any corresponding change in the cooling water inlet temperature, would probably be caused by （）.
Pitting in the suction areas of a centrifugal pump bronze impeller is usually caused by （）.