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 Engine-Driven Pump

  • The hydraulic system uses an EDP to supply the pressurized hydraulic fluid for the flight control system and utility systems; therefore, EDP is the most important a component in the hydraulic system.
  • The typical EDP is a pressure-compensated, variable displacement axial piston pump capable of delivering a
  • variable the volume of fluid to maintain pressure in a hydraulic system.
  • The EDP is normally mounted to the engine gearbox and driven by a splined input shaft, the outside view and cross-sectional view of the EDP, in which nine pistons are nested in a circular array within the cylinder barrel.
  • The external interface of the EDP includes the drive shaft, mounting flange, inlet,
  • discharge, and case drain outlet.
  • The inside of the EDP includes the cylinder barrel, piston, port plate, hanger, transmission shaft, and swashplate. The cylinder barrel is held tightly against the port plate using the compressed force of the spring.
  •  A thin film of oil separates the port plate from the cylinder barrel, which forms a hydrodynamic bearing between the cylinder barrel and port plate under normal conditions.
  •  The cylinder barrel is connected to the shaft through a set of splines that run parallel to the shaft. The port plate has
  • two kidney-shaped ports that connect the inlet port and drain-out port, respectively.
  • Fluid enters and leaves the barrel through the kidney-shaped slots in the port cap.
  •  A ball-and-socket joint connects the base of each piston to a slipper.
  •  The slippers are kept in reasonable contact with the swash plate by a retainer, where a hydrostatic and hydrodynamic bearing surface separates the slippers from the swashplate.
  • The swashplate angle varies with time to create variable displacement of the pump.

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