GB1287099A - Improvements in or relating to aircraft ground-wheel steering mechanisms - Google Patents

Abstract

1287099 Steering aircraft ground wheels HAWKER SIDDELEY DYNAMICS Ltd 15 Dec 1969 [13 Dec 1968] 59507/68 Heading B7H An aircraft ground wheel e.g. nosewheel, steering mechanism includes a rack-and-pinion assembly in which the pinion has around a minor portion of its periphery so that when the pinion 1 runs out of mesh with the rack 4 castoring is possible, provision being made to lock the rack in the position, in either direction of steering, at which it ceases to be in driving engagement with the pinion. As shown the rack 4, connected to power pistons 5, 5a is movable to the left or right by its engagement with teeth 11 of the rotatable pinion 1. At the position at which the rack and pinion run out of mesh during steering a recess 16 is provided in the rack housing. The rack is provided with a pair of detents 6, 6a co-operable with the recess to lock the rack at that position. The detents are biased by springs such as to oppose any tendency for them to enter the recess, pressure being exerted, to oppose this bias, during rotation of the pinion, by cut-aways 17 and a cam surface 19 on the pinion acting on the head of a detent as the rack moves. Once engaged in the recess, a detent is retained therein by the cam surface 19 until the pinion returns to re-engage with the rack. The rack is constructed in two halves bolted together. In modifications (not shown), the detents and co-operating cam are arranged away from the plane of rotation of the teeth 11 and the cam is separate from the gear, and the rack is a one-piece part.