Patent ID: 6059228
Filing Date: 2000-05-09
Classification: B64C

Abstract:
A hydraulic system for retracting into and extending out of the body of an aircraft a landing gear for use in taking off and landing, comprising:a housing unit formed with a pressure imparting port to be connected with a fluid pressure reservoir and a pressure inlet/outlet port to be connected with an up-lock cylinder,a hydraulic pump accommodated in said housing unit to discharge therefrom and introduced therein a hydraulic fluid,a driving motor drivably connected with said hydraulic pump to impart rotation motion to said hydraulic pump,a hydraulic actuator accommodated in said housing unit and having a piston rod assembly received therein to be reciprocably moved by said hydraulic pump to assume two different positions consisting a retraction position where said piston rod assembly is positioned at its retracted position and locked by said up-lock cylinder and an extended position where said piston rod assembly is positioned at its extended position,a shuttle valve accommodated in said housing unit and positioned between said hydraulic pump and said hydraulic actuator and movable with respect to said housing unit to assume two different positions for selectively changing the flow of said hydraulic fluid between said hydraulic pump and said hydraulic actuator,an emergency valve accommodated in said housing unit and positioned between said hydraulic pump and said hydraulic actuator and between said pressure imparting port and said hydraulic actuator and movable with respect to said housing unit to assume two different positions for selectively changing the flow of said hydraulic fluid between said hydraulic pump and said hydraulic actuator and the flow of said hydraulic pump and said fluid pressure reservoir,an actuator pressure releasing mechanism accommodated in said housing unit to release said hydraulic pressure in said hydraulic actuator to allow said piston rod assembly to be freely moved with respect to said housing unit toward said extended position of said piston rod assembly, anda mechanically locking mechanism accommodated in said housing unit to lock said piston rod assembly with said housing unit when said hydraulic pump is not driven by said driving motor and to unlock said piston rod assembly from said housing unit to be freely moved when said hydraulic pump is driven by said driving motor.