Hydraulic fluid contamination may result in hydraulic failure and thus poses a threat to flight safety.

The automatic transmission consists of hydraulic torque converter, planetary gear sets and hydraulic control sets.

Hydraulic systems can provide hydraulic power for elevators so that to reduce the control force of the pilot for pitch control.

hydraulic power-assisted steering system______

The commonly used pressure control valve in hydraulic transmission system is ( ) A: directional valve B: relief valve C: hydraulic control check valve

Hydraulic machinery failures are commonly caused by contamination of the hydraulic fluid and （）. A: fluid friction B: fluid turbulence C: component misalignment D: pressure surge

The most common contaminate of governor hydraulic fluid is （）.

For cold environment, heater is necessary for hydraulic system.

词汇与结构 The flight controls are powered by redundant hydraulic sources: system A and system B. _________ hydraulic system can operate all primary flight controls.

Which is the correct removal sequence of the equipment in the fully mechanized working face? ( ) A: Scraper conveyor, double-drum shearer, retractable belt conveyor, hydraulic support B: Double-drum shearer, retractable belt conveyor, scraper conveyor, hydraulic support C: Double-drum shearer, scraper conveyor, retractable belt conveyor, hydraulic support D: Retractable belt conveyor, double-drum shearer, scraper conveyor, hydraulic support