单项选择题
A.pump bearings in poor condition B.excessively worn actuator-piston packing C.broken directional control valve centering springs D.low hydraulic oil viscosity
Most solenoid valves are actuated by （）.A.a springB.an ...
单项选择题Most solenoid valves are actuated by （）.
A.a spring B.an electromagnet C.the force of gravity D.refrigerant pressure
When normal operating pressure is applied to the hydrau...
单项选择题When normal operating pressure is applied to the hydraulic oil used in a high-pressure system, the oil （）.
A.viscosity will decrease B.volume will increase C.volume will decrease D.pour point will be reduced
If the refrigeration compressor crankcase is sweating, ...
单项选择题If the refrigeration compressor crankcase is sweating, the cause may be due to （）.
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
