A.set for maximum torque
B.on the purge and vent stroke
C.in the neutral position
D.rotating backwards
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A.frames
B.joiners
C.longitudinals
D.knees
A.pump bearings in poor condition
B.excessively worn actuator-piston packing
C.broken directional control valve centering springs
D.low hydraulic oil viscosity
A.a spring
B.an electromagnet
C.the force of gravity
D.refrigerant pressure
A.viscosity will decrease
B.volume will increase
C.volume will decrease
D.pour point will be reduced
A.a shortage of refrigerant
B.the compressor running continuously
C.liquid refrigerant returning to the compressor
D.the compressor short cycling on the high pressure cutout
最新試題
The output volume of a positive fixed displacement pump can be changed only by （）.
An increasing head pressure in a refrigeration system, without any corresponding change in the cooling water inlet temperature, would probably be caused by （）.
An excessive charge of refrigerant in an air-cooled refrigeration system can cause （）.
The rate of heat transfer from a hot region to a cold region is affected most by the （）.
Which of the following statements is correct concerning heat transfer?（）
Which of the problems listed would came the discharge temperature of an R-12 refrigeration compressor to increase?（）
Which of the following problems could cause the high pressure cutout switch to shut down the compressor in a refrigeration system?（）
If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will （）.
Which of the listed pumps is NOT a positive displacement pump?（）
The amount of fluid friction or internal friction inherent in a mineral lubricating oil is reflected as a measure of its （）.