GB533431A - Improvements in aeroplane undercarriages - Google Patents

Abstract

533,431. Aircraft landing gear. SOC. D'INVENTIONS AERONAUTIQUES ET MECANIQUES, S.I.A.M. Julv 22, 1939, No. 21350. Convention date, July 26, 1938. [Class 4] [Also in Group XXXII] A retractable undercarriage, which is -decreased in length by mechanical means as it is retracted, is provided with a shock absorber having a liquid chamber connected to an auxiliary receptacle by a pipe provided with a normally closed valve, the valve being opened by the pilot or automatically, when retraction takes place. An undercarriage leg, pivoted to the aircraft at 2, comprises a cylinder 3, filled with oil, in which works a piston 4 connected to a hollow rod 8. A permanently open passage 5 is provided through the piston and other passages 7 are closed by a valve 6 under load shocks. A piston 12 encloses a body of compressed air in the hollow rod 8 to act as the resilient element. An annular space 10, also filled with oil, communicates with a bell chamber 16 through a pipe 14 and a valve 15 which allows free flow to the space 10 but restricts flow in the opposite direction. The top of the cylinder 3 communicates with a chamber 18 in which is a normally closed valve 19, the lower part 24 of the chamber being in communication with the bell chamber at 16. As shown, upon starting a pump 26 to actuate a hydraulic jack for swinging the leg in the direction of the arrow f, a piston 23 in the part 24 raises the valve 19 to allow oil to flow from the cylinder 3 to the bell chamber 16, the hollow rod 8 being caused to telescope into the cylinder 3 by a cable connection 28. Instead of being closed the chamber 16 may be open to atmosphere, but the pressure built up in a closed chamber, although considerably less than the pressure in the hollow piston rod 8, assists in the extension of the leg when the latter is lowered. Specification 425,207 is referred to.