GB709340A - Improvements in and relating to aircraft undercarriages - Google Patents

Abstract

709,340. Hydro-pneumatic shock-absorbers. BOULTON PAUL AIRCRAFT, Ltd. March 12, 1952 [March 13, 1951J, No. 5981/51. Class 108(3) A wheel-mounting unit for an aircraft t undercarriage comprises a combination of cantilever and articulated type units in which the normally-fixed member of one unit constitutes or carries the movable member of the other unit. In the construction 'shown in Fig. 2, the articulated unit comprises a cylinder 1 in which a piston 18 works. The piston rod 19 is linked to an intermediate point of an arm 15 which carries the aircraft wheel (not shown) at one end, and is fulcrummed at 16 to a bracket 14 rigid with the cylinder I. Liquid in the cylinder 1 is displaced by upward piston movement, through a valvecontrolled orifice 21 to displace a floating piston 22 against air pressure in the hollow piston rod. The cantilever unit is formed by the cylinder 1 and an outer cylinder 2. A head 4 on the cylinder 1 acts on liquid 8 and displaces it through an orifice n and a valve 13 to act on a floating piston 23 loaded by air pressure in an extension 60 of the cylinder 1. The valve 13 may be a valve of the kind described in Specification 707,970, [Group XXIX], and maintains a constant pressure across itself. In a modification, Fig. 1 (not shown), extension 60 is solid and carries a piston which has merely a dashpot action in the liquid 8. This piston may have an orifice, or controlled leakage may occur around its periphery. It also has a valve corresponding to the valve 13 of Fig. 2. In the construction shown in Fig. 3, the liquid space of both articulated and cantilever units are in communication tnrough orifices 110, and this liquid acts on a single floating piston 22. The leverage of the arm 15 and the ratio of areas of the pistons 4, 18 may be selected to cause closing of the articulated unit before the cantilever unit, or vice versa. Air may be charged into the hollow piston rod 19 through a valve which is slidable in a slot in the cylinder 1. A liquid-spring unit may be used instead of the hydro-pneumatic arrangements described.