Retractable landing gear for aircraft

Retractable landing gear for an aircraft, the landing gear being of the type that is raised vertically and comprising a plurality of independent legs arranged one behind another to form, in the gear-down position, a row parallel to the longitudinal midplane of the aircraft, each leg comprising a structural part rigidly secured to a structure of the aircraft, a rocker beam hinged to the bottom end of said structural part so that said rocker beam is movable in a vertical plane together with its pair of wheels, and a shock absorber associated with the rocker beam and comprising a main strut and a rod piston having one end slidably received in said main strut coaxially about the axis thereof, wherein the shock absorber of each leg is extended by a positioning portion comprising a secondary strut sliding telescopically on the other end of the rod piston of said shock absorber, co-operating with the end wall of said rod piston to define a secondary hydraulic fluid chamber which is connected to an associated control circuit, thus enabling the total length of the extended shock absorber to be shortened in order to collapse said leg, and wherein each leg further includes a positioning actuator connected in hinged manner to the extended shock absorber, being arranged so that the assembly constituted by said positioning actuator and said extended shock absorber is interposed between an appendix of the rocker beam and at least one moving element forming part of the control rodding of the landing gear, a link rod also being interposed between the rocker beam and the hinged zone between the positioning actuator and the extended shock absorber, said positioning actuator being arranged to lengthen relative to a normal use position in order to lengthen the corresponding leg.