A.aeration of the oilB.contamination of the oilC.pump c……

单项选择题A grease gun is generally used to lubricate a （）.

A.condensate pump ball bearing
B.main shaft bearing
C.main turbine bearing
D.diesel engine wrist pin bearing

单项选择题Thermostatic expansion valves can be adjusted for （）.

A.suction pressure only
B.head pressure only
C.superheat only
D.suction pressure and box temperature

单项选择题The amount of fluid friction or internal friction inherent in a mineral lubricating oil is reflected as a measure of its （）.

A.specific gravity
B.viscosity
C.S E number
D.hydrolytic stability

单项选择题The major source of chemical contaminants in hydraulic fluid is （）.

A.microscopic steel shavings
B.abrasive waste
C.anti-oxidant compounds
D.oxidation by-products

单项选择题If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will （）.

A.increase the capacity of the coil
B.increase the superheat at the bulb
C.deliver more refrigerant to the coil
D.decrease the capacity of the coil