Dual steering system for vehicle

Claim 1

A vehicle having a vehicle chassis supported by a pair of steerable front wheels and at least one pair of rear wheels with said front wheels supported for movement about vertical axes to steer said vehicle, a cab rotated about a vertical axis on said chassis, and a dual steering system for said vehicle, said dual steering system including a hydrostatic steering system, a mechanical actuated power steering system and a steering wheel in said cab common to both said systems; said hydrostatic steering system including a hydrostatic steering valve in said cab, a pressurized fluid source and a reservoir connected to said valve, a fluid ram having one element connected to said chassis and a second element connected to said front wheels, and conduit means connecting said valve to said fluid ram; said mechanical actuated power steering system including a steering gear secured to said chassis and having an input shaft and an output shaft, linkage means connecting said output shaft to said front wheels, a disconnectable linkage system extending from said input shaft to said cab adjacent said steering wheel; and a selector unit in said cab adjacent said steering wheel for selectively connecting said steering wheel to said steering valve or said linkage system so that said vehicle may be steered by either said hydrostatic steering system or said mechanical actuated power steering system.