GB704080A - Improvements in and relating to retractable aircraft undercarriages - Google Patents

Abstract

704,080. Retractable undercarriages for aircraft. BOULTON PAUL AIRCRAFT, Ltd. Nov. 19, 1951 [Nov. 17, 1950], No. 28212/50. Class 4 A retractable aircraft undercarriage of the kind having a break back strut for holding a wheel mounting in the extended position and interengaging locking members carried one on the wheel mounting and the other on the aircraft for holding the mounting in the retracted position has one element of a retraction jack operatively connected to the wheel mounting and the other element operatively connected to the break-back strut through a member movable relative to said strut within the limits of a lost motion mechanism, said member being operative in one direction of said relative movement to release the interengaging locking members holding the undercarriage in the retracted position, and in the other direction of said relative movement to release locking means tor locking the break-back strut in the extended or straight position. The undercarriage leg 1 is pivoted at 2 to the aircraft structure for sideways retraction, an arm 13 fast with the leg being connected to one end of a retraction jack 9. the other end of which is connected at 10 to an arm (not shown) fast with a rotatable shaft 8. A break-back strut comprising members 4 and 5, pivotally connected at 6, is freely pivoted at 7 to the leg 1 and to the shaft 8, which carries adjacent to the arm 4 a plate 28 having a slot 29 engaging with a peg 30 fast with the arm 4. A further arm 31 fast with the shaft 8 has a pivotal connection 32 with one end of an articulated spring loaded rod 33 the other end of which is connected to a hooked catch 34 pivoted to the arm 4 to engage a roller 36 on the arm 5 when the break-back strut is extended. An up-lock arm 20 is pivoted at 24, Fig. 1. to the aircraft structure and carries a roller 26 acted upon by a cam 27 fast with the shaft 8. With the undercarriage in the position shown in Fig. 1, initial. extension of the jack 9 rotates the shaft 8 and acts on the linkage 33 to release the catch 34, 36 and free the strut 4, 5 with lost-motion movement of the slot 29 over the pin 30. Further extension of the jack causes the plate 28 to act on the pin 30 to break the strut 4, 5 and initiate retraction of the leg 1 from which position continued extension of the jack exerts a leverage on the shaft 8 and the arm 13 to raise the leg to the retracted position where a roller thereon engages the catch 20. During lowering movement, initial movement of the jack rotates the shaft 8 in the opposite direction so that the cam 27 acts on the roller 26 and the lever 20 to release the roller on the leg, the mechanism then operating in the reverse manner to that described.