Patent GB-1353151-A (GB)
Title: Aircraft undercarriage assembly
IPC: B64C25/20
Filed: 1970-04-27
Abstract: 1353151 Aircraft undercarriage assemblies AUTOMOTIVE PRODUCTS Ltd 20 April 1971 [27 April 1970] 20144/70 Heading B7G An aircraft undercarriage assembly comprises: a leg 10 having a supporting arm 12 and pivoted at 11 to the aircraft structure; and a jack 16 having a rod 17 pivoted to a locking member 14 which in turn is pivoted to the supporting arm 12 at 15, pivoting of the leg being limited in the extended position (solid lines) by engagement of surfaces 14A and 25 on the locking member 14 with corresponding surfaces 35A and 35B of the aircraft structure and in the retracted position (chain lines) by abutment of the surfaces 25 with the surface 54 of a bracket 51 fixed to the aircraft structure and subsequent engagement of the surface of recess 27 of the locking member 14 with roller 52. To retract the undercarriage, pressure fluid is fed firstly into a latch actuating mechanism 41 which pivots a latch lever 36 to free the locking member to rotate anticlockwise when the rod 17 is extended by the pressure fluid, for example, after it has passed sequencing valves. A peg 21 fixed to the supporting arm 12 engages the end of a slot 22 in the locking member nearest the pivot 20 to stop the rotation. Further extension of the rod 17 rotates the leg 10 with the locking member 14 anticlockwise about pivot 11 until the surface 25 abuts the surface 54. Then a cam surface 26 on the locking member 14 follows a roller 52 on the bracket 51 and a recess 27 engages the roller 52 thereby forming an uplock 1. To extend the undercarriage the rod 17 is retracted to cause firstly disengagement of the recess 27 from the roller 52 then secondly pivoting of the leg 10 and locking member 14 clockwise until the surfaces 14A and 25 abut the surfaces 35A and 35B respectively and the latch 36 is engaged, the latch 36 being spring biased by the latch actuating mechanism 41 to the position shown. A resiliently compressible strut 28 is provided to bias the locking member against anticlockwise pivoting. In the event of failure of the pressure fluid system, a manually operated snail cam 53 on the bracket 51 is rotated anticlockwise to disengage the recess 27 from the roller, the leg 10 falling under the effect of gravity to its extended position. In another embodiment, Figs. 3 to 5 (not shown) the rod (17) is pivoted to a lever plate (57) mounted pivotally on the leg (10) and a member (58) fixedly attached to the locking member (14) transmits motion of the plate (57) to the locking member (14) which is no longer limited in movement by a peg but only by resiliently compressible strut (28). The shape of the locking member and the abutment surfaces for limiting the rotation of the leg are modified and the leg rotates in the opposite sense to that of the first embodiment. In a further embodiment, Figs. 3, 4 and 5 (not shown) the jack acts on the locking member through a lever plate biased to engage a cam surface on the locking member, the lever plate instead of the locking member having the pin- and-slot which restricts its rotation. This locking member, as a result, rotates in the opposite sense to the locking member of the other embodiment.