GB460361A - Improvements relating to shock absorbers - Google Patents

Abstract

460,361. Shock-absorbers. BARKER, G. G. (Bendix Aviation Corporation) April 17, 1935, No. 29725/36. Divided out of 456,897 under which a Specification was laid open to inspection under Sect. 91 of the Acts, Oct. 28, 1935. [Class 108 (iii)] A fluid shock-absorbing strut for aircraft is constructed so as to absorb the energy of the landing shock, excluding that portion absorbed by the tyre of the landing- wheel associated with the strut, at a constant rate during the greater part of its stroke and at a reduced rate during the last part of its stroke in order to decrease the pressure on the tyre and allow the tyre to expand and transfer the energy stored therein to the strut. As shown the shockabsorber comprises telescopic tubular members 10, 11 closed at their opposite ends by plugs 12, 13 adapted for attachment to relatively-movable parts of an aeroplane landing-gear. On compression of the shock-absorber, liquid is forced through an orifice 21 in a piston 20 forming the inner end of the member 10, the flow being regulated by a metering pin 2 3 fixed to the member 11. In order to maintain a constant resistance over the greater portion of the stroke of the piston 20 it is explained in the Specification that the ratio between the velocity of the piston and the area of the orifice available for flow of liquid should be constant. Accordingly, the metering pin 23. is provided with a knob-like upper portion 24 and with portions which decrease to a minimum at part 25 and increase to part 26. A helical spring 18 surrounding the member 10 is adapted to come into action with the portion of the pin below part 26, which allows slight flow of liquid through the orifice, the decrease in hydraulic resistance occurring more rapidly than the increase in the resistance of the spring so that the combined resistance becomes temporarily decreased, thus permitting the tyre to expand before completion of the stroke. An air cushion in the member 10 may supplement the spring 18. In a modification, the part 25 occurs nearer the upper end of the pin.