GB650878A - Improvements in or relating to fluid pressure actuated control steering systems - Google Patents

Abstract

650,878. Aircraft undercarriages. ELECTROHYDRAULICS, Ltd. Oct. 20, 1947, No. 23128. [Class 4] [Also in Group XXIX] In a fluid pressure system for actuating the steerable wheels on an aircraft undercarriage and of the kind comprising a fluidpressure actuating motor controlled by a selector valve device and a followup mechanism and with a centralizing device between the initial control member, and the wheels, the latter can normally move freely under the action of external forces but, when the control member is initially displaced relative to the wheels, the latter become locked and a further relative displacement of the control member causes the motor to drive them in a sense to reduce the displacement. In an embodiment, the wheels 108 are carried by a tube 105 slidable in a leg 100. The actuating mechanism comprises two single acting jack pistons 125 interconnected by a rack in mesh with a toothed quadrant which is connected by curved toggle links 120, 119 to a sleeve 114 rotatable relative to the leg 100. The toothed quadrant is also connected through gearing to a torque rod 137 to provide a repeatback or follow-up signal, the rotation of rod 137 being communicated to a further rod 143 through a knee-joint 142. Sleeve 114 is connected to tube 105 by toggle links 116 and carries a cam 110 which co-operates with a further cam 111 on tube 105 to allow of centering when the wheels are extended. A shock absorber 113 is fixed to the axle bracket of the wheels and is rotatably mounted in a flange 117 in the leg.