GB1356136A - Steering system - Google Patents

Abstract

1356136 Vehicle steering mechanism INTERNATIONAL HARVESTER CO 7 July 1971 [7 July 1970] 31929/71 Heading B7H A steering system for steering the wheels 94, 294 on two axles 92, 292 of an aircraft tow tractor in two wheel, four wheel and crab steering modes from control stations 10, 11 at both ends of the vehicle comprises a directional control valve 50 operable from either control station 10, 11 for controlling fluid-actuated means for turning the wheels, a pair of mode control valves 62, 262 actuated by cylinders 64, 264 for controlling fluid flow from the valve 50, a pair of mode selector valves 70, 270 for directing fluid to the cylinders 64, 264, and a station selector valve 38 for rendering operative selec ted ones of the control stations 10, 12 and mode selector valves 70, 270. The cylinder 64, 264 controlled by the unselected valve 70, 270 automatically moves into a position in which its associated axle 92, 292 responds to the selected control station 10, 11 so that both axles can be steered from that station. The control stations 10, 11 include respective steering wheels 14, 214 for actuating hand pumps 12, 212, the selected one of which is connected to hydraulic actuators 32, 36 for the valve 50 through hand pump selector valves 20, 22 position by a cylinder 24 controlled by the station selector valve 40. The directional control valve 59 directs fluid from a pilot pump 54 through the mode control valves 62, 262 to sensing cylinders 100, 300 which are connected between steering arms 98,298 on the wheels 94, 294 and power steering valves 110, 310 controlling flow of fluid from main pumps 126, 326 to steering rams 116, 316. As described with reference to Fig. 2 (not shown) the vehicle has two engines and comprises in accordance with Specification 1,356,137 first and second pumps drivable by one engine, and third and fourth pumps drivable by the other engine, the first and third pumps and the second and fourth pumps serving as main steering pumps for the respective axles so that both axles are steerable when either engine is operating. The sensing cylinders are as described in Specification 1,356,138.