GB906848A - A shock absorbing strut - Google Patents

Abstract

906,848. Hydro-pneumatic shock absorbers. FLUGZEUGWERKE DRESDEN VEB. Dec. 30, 1960, No. 44742/60. Class 108(3). A shock - absorber strut, e.g. for the forward end of a tandemtype aircraft landing gear and which compensates for braking torque and retains a selected angle of incidence, comprises a supplementary piston 4 which is accommodated within a principal piston and rod 2, 3 housed within a cylinder 1 the piston 2, which is loaded by a compression spring 6, dividing the cylinder 1 into a cylinder chamber 10, which is supplied with gas. under pressure through a filling opening 7, and an annular chamber 11 having an opening 9 which communicates, through a connection having a non-return valve, with the hydraulic system of the brakes. A cavity 13 in the supplementary piston and rod 4, 5 communicates through ports 8 with an inner annular chamber 12 around the rod 3 compressed air, at a pressure which exceeds that of the maximum pressure in the cylinder chamber 10, being supplied to the inner annular chamber 12 through a filling valve in an abutment 15. The inner annular chamber 12 contains a ring 20 which limits the stroke of the supplementary piston 4. Lugs 21, 22 are provided on the supplementary piston rod 5 and the cylinder 1 for connection respectively with the wheel carriage and the aircraft body. When the wheels of the aircraft first touch the ground the capacity of the annular chamber 11 is reduced and the spring 6 is compressed, hydraulic pressure, proportional to the braking pressure, being transmitted to the annular chamber 11 when the brakes are applied. If the strut is overloaded or, if the hydraulic damping due to the brakes exceeds a predetermined value, the supplementary piston rod 5 is forced out of the principal piston rod 3.