As the landing gear is lowered, its weight acts on the fluid in the lower end of power cylinder 1, forcing it out into valve chamber a. The fluid moves plunger 2 downward together with valve member 3, and the fluid, raising valve member 4, is admitted into the upper end of cylinder 1. Fluid is also delivered by pump 5 to the upper end, moving down piston 8 and lowering the landing gear. After the landing gear has been lowered to an extent that the pressure of the fluid from its weight is no longer capable of compressing springs 6 and 7, spring 6 closes valve member 4. Piston 8 continues to move downward from the pressure of the fluid delivered by pump 5. At this, fluid discharged from the lower end of cylinder 1 shifts plunger 2 downward and passes through port f and directional valve 9 to the tank. To retract the landing gear, valve 9 is turned 90°, fluid is delivered by pump 5 to port d, shifting plunger 2 upward and compressing spring 10, and through port b to the lower end of cylinder 1. This moves piston 8 upward, retracting the landing gear.
$4280$CHP,AL$