A.hydraulic steering B.follow-up steering C.remote control steering D.air controlled steering
A.（1）and（2） B.（1），（2）and（3） C.（1）and（3） D.（2）and（3）
A.maintain radial alignment between the pump impeller and casing B.absorb all impeller shaft end thrust C.prevent water leakage to the atmosphere D.prevent wear of the pump casing and/or impeller
A.warm-up allows the hydraulic system to become charged with oil B.warm-up allows the relief valves to be properly tested C.hydraulic strainers operate only during the warm-up period D.hydraulic fluid must be at the proper viscosity
A.positive displacement B.ejector C.centrifugal D.air compressor
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