STEERING SYSTEM FOR HYDROSTATICALLY DRIVEN FRONT TRAVELLING WHEELS OF A VEHICLE AND CONTROLLED BACK SELF-CASTERING WHEELS

摘要

An integrated steering system comprises a main valve, an automatic valve and a back wheels control valve. The steering wheel provides actuation of the main valve of the steering system, the main valve being of the type that has a characteristic leak. Receiving of information on motion of the steering wheel is provided, and an associated signal is sent; as a result, the automatic valve of the steering system is actuated for replenishment of working fluid that is fed to the steering cylinder by means of the main valve of the steering system for compensation of the leak, the amount of working fluid added depending on the vehicle travel speed. An electric positional feedback actuator is used for travel speed monitoring. Every time when the actuator position indicates that the travel speed became zero, and the switch in the slot of the hydraulic control handle indicates that the handle is in the initial position, the automatic valve of the steering system will be actuated for moving the steering cylinder to the neutral position corresponding to direct forward movement that is defined by a sensor in the lever mechanism of the steering system.