GB576113A - Improvements in and relating to aircraft undercarriages - Google Patents

Abstract

576,113. Retractable undercarriages. BOULTON PAUL AIRCRAFT, Ltd., BATCHELOR, .J. W., and CLARK, B. F. March 11, 1944, No. 4571. [Class 4] A retractable undercarriage comprises an oleo-pneumatic shock-absorber which is compressed during retraction, liquid being transferred from the shock-absorber to a chamber in the hydraulic retracting jack, said chamber containing a piston movable with the operating piston to admit the transferred liquid into the chamber during retraction and to return the liquid to the shock-absorber during extension of the undercarriage. In the form illustrated, the undercarriage is in the form of a parallel linkage 1, 2, 3, 4, the limb 3 being hinged to the airframe structure at 5 and an oleo-pneumatic shock-absorber 6 is connected between the hinge 5 and the member 4. A telescopic tie 8 or equivalent member is connected between the member 2 and a point Z offset from the hinge axis 5, such that during retraction, effected by a hydraulic jack 7, the parallel linkage is deformed to shorten the length of the undercarriage for stowage. During retraction, liquid in the shock-absorber 6 is transferred to a chamber 7a forming an extension of the main jack 7, an auxiliary piston 10 connected to the operating piston 9 moving with the latter to admit the liquid to, and return it from, the chamber 7a. Liquid transfer is normally prevented by a spring- loaded ball valve 12, the latter being opened during retraction by mechanical means or by a pilot hydraulic jack.