VEHICLE STEERING APPARATUS

摘要

A mechanical-over-hydraulic steering apparatus (49) capable of providing automotive-type steering includes a steering wheel driven input control member (130), right and left turn control valves (224, 276), and first and second actuators (158, 160) mounted for rotation along an axis (132) common with the input control member. Each of the actuators has a cam (178, 242) operatively associated with a cam-following roller assembly (202, 266) that operates the respective control valve. The vehicle (10) has a cross drive mechanism (22), and the steering apparatus includes an over-center variable displacement steering pump (86) and associated displacement control (91) controllably operated by first and second pilot lines (112, 114) connected to the right and left turn control valves. The steering pump controllably and bidirectionally communicates fluid to a steering motor (82) for the steering input to the cross drive mechanism.