Multi-Mode Electrohydraulic Steering System for Off-Road Vehicles

Many mobile vehicles require four-wheel steering modes in order Co enhance mobility in tight spaces. Not only is four-wheel steering required, but three modes are also desired for a variety of mobility problems of off road vehicles.

Typically three modes of steering are required: 1.) Standard steering; 2.) Coordinated; and 3.) Crab. The rear steering operation should be automatic and proportional allowing the operator to give full attention to the front steering and other vehicle operations. Also, switching from one steering mode to another must be simple and quick.

Through the use of inexpensive analog electronics and proportional hydraulic components, a reliable servo steering system capable of three modes can be constructed. This paper will consider the following areas of design: 1.) Hydraulic design requirements and considerations; 2.) Electronic design requirements and considerations; and 3.) System operation and set-up.