Abstract: A full-time all wheel steering system is provided whereby the rear wheel angle is determined by the front wheel angle and a relational curve, polynomial equation or set of tabulated values. The front wheel angle is measured and the desired rear wheel angle is calculated by a programmable controller. If the desired rear wheel angle is not sufficiently close to the actual rear wheel angle, the controller means sends a signal which results in adjustment of the rear wheel angle. The desired rear wheel angle may be a function of the vehicle speed as well as the front wheel angle. A dead band may be employed which maintains the rear wheels in a straight ahead position when the front wheel angle does not exceed the dead band value. The maximum rear wheel cramp angle may also be controlled as a function of vehicle speed. The system is applicable to passenger cars, trucks and tractor-trailer rigs.

Abstract: A full-time all wheel steering system is provided whereby the rear wheel angle is determined by the front wheel angle and a relational curve, polynomial equation or set of tabulated values. The front wheel angle is measured and the desired rear wheel angle is calculated by a programmable controller. If the desired rear wheel angle is not sufficiently close to the actual rear wheel angle, the controller means sends a signal which results in adjustment of the rear wheel angle. The desired rear wheel angle may be a function of the vehicle speed as well as the front wheel angle. Further, the operator may select from a plurality of relational curves, polynomial equations, tabulated values as well as a plurality of manually selectable modes including an independent rear wheel steering mode. The system is applicable to passenger cars, trucks and tractor-trailer rigs.