GB494557A - Improved automatic means for ensuring extension of retractable alighting gear for aircraft - Google Patents

Abstract

494,557. Retractable landing - gear for aircraft. POTEZ, H. C. A. March 22, 1938, No. 8743. Convention date, Feb. 9. [Class 4] A retractable, alighting-gear for aircraft of the kind comprising a swinging leg and a folding strut is provided with means acting after the manner of a compression spring and having its ends attached one to each half of the folding strut in such manner as to tend to straighten the said strut against the action of the retraction mechanism. As applied to a wheel landing gear, Figs. 1 and 3, a strut 3 pivoted to the aircraft at 4, carries a wheel axle at 2, and is braced by a folding strut comprising elements 7, 8 pivoted together at 9 at which point the force for retraction is applied. In the " down " position, element 8 rests against a stop 13. A compression spring or equivalent 12 is arranged between extremities A, B of members 10, 11 respectively mounted on elements 7, 8. In the " down " position the compression force of the spring gives rise to a couple tending to maintain the strut 3 in the extended position and in a position intermediate the " down " and " up " positions, the extending couple has a high value, but in the " up " position, Fig. 3, the couple vanishes or changes. in sign. Thus, during the first stage of extension, the wheel falls under gravity and is; thereafter urged by the device 12 into operative position. The device 12 may take the form of a cylinder 14 having a gland at 16 for the passage of a hollow piston 17 of which the bore is extended by a pipe 19 communicating with a tank 18. The device is pivotally connected to members 10 and 11 by a lug 15 at one end and by journals 21 formed on a cylinder 20 at the other. The cylinder and piston may be filled with liquid and tank 18 contains a gas under pressure, but by suitable modification of gland 16, air alone may be employed, tube 19 or both tube and tank being omitted.