A.decreased clearances between rotating parts
B.decreased slippage to the suction side of the pump
C.air binding in the discharge ports
D.erosion and excessive wear
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A.a shortage of refrigerant in the system
B.air in the system
C.an accumulation of liquid refrigerant in the crankcase
D.a shortage of oil in the crankcase
A.ram relief valves bypass oil to stop rudder movement
B.six-way valve shifts to the neutral flow position
C.steering pump electric motor is de - energized by the transfer switch
D.follow-up gear takes the hydraulic pump off stroke
A.maintain a preset pressure on the line
B.closely regulate the amount of flow
C.relieve excessive pressure on the line
D.allow flow in one direction only
A.insufficient load
B.excessively high oil viscosity
C.relief-valve pressure setting too high
D.reservoir level being maintained two inches above normal
A.a defective or broken high pressure un-loader
B.a loose valve plate
C.excessive overload
D.no compression
最新試題
If the viscosity of the liquid being transferred remains constant as the discharge pressure increases, the rotary pump （）.
When a refrigeration compressor has developed a high head pressure as a result of a refrigerant overcharge, you should （）.
On tank vessels equipped with power operated cargo tank valves, the type of power operator most commonly used is （）.
Thermostatic expansion valves can be adjusted for （）.
The rate of heat transfer between the hot and cold fluids passing through a shell-and-tube type heat exchanger will （）.
Which of the following statements is correct concerning heat transfer?（）
Low compressor head pressure in a refrigeration system can be caused by（）.
If the head pressure of a reciprocating refrigeration compressor is excessive, （）.
The rate of heat transfer from a hot region to a cold region is affected most by the （）.
Which of the listed pumps is NOT a positive displacement pump?（）