Hydrostatic Steering System Design in Tractors

Hydrostatic Steering System Design in Tractors

HYDROSTATIC STEERING SYSTEM DESIGN IN TRACTORS

In the framework of this study, the design of the steering mechanism and its hydrostatic drive system and auxiliary hydraulic system in the tractor based on the "Ackerman Rotation Geometry" criteria, the strength analysis of the steering limbs using the finite element method, prototype manufacturing, testing with the help of a hydraulic assembly installed in accordance with the specifications and A summary of the applications carried out in serial production is presented.
The front track widths of the tractors must be adjustable. This is provided by adjustable tie rods. Since a different mechanism is formed for each position of the rod arms, kinematic analysis of the mechanism should be made by considering the safety parameter for each track width and the above-mentioned rotation geometry criterion should be adhered to for a healthy rotation. At the end of this study, in which the number of rotations of the steering wheel in the specifications are also taken into consideration, the size of the hydraulic equipment to be used such as the steering unit (orbitrol), steering cylinder, steering pump is revealed.
Within the scope of the test studies, in addition to the work carried out with the front loader, which is the situation where the steering system and front axle of the tractor are the most stressed, a hydraulic mechanism designed to ensure that the steering mechanism is forced at the same pressure value despite the changing kinematic position at every deviation angle.

Hydrostatic steering systems are fully hydraulic driven steering systems where there is no mechanical connection between the steering wheel and the steering mechanism that ensures the correct steering of the steering wheels. In the development process of tractor steering systems, starting from the 1910s, completely mechanical driven steering systems, in the 1950s and 60s hydraulic assisted steering systems and today hydrostatic driven steering systems. This development is moving towards electro-hydraulic and all-electric steering control.
The hydrostatic steering system basically consists of an engine driven steering pump, a steering valve coupled to the steering wheel, and a steering mechanism with a steering actuator (usually hydraulic cylinder or cylinders). As an oil reservoir, the tank of a pump with a self-contained tank or the central body of the tractor can be used as a common tank with other hydraulic circuits (Figure-1). In addition, depending on the hydraulic system setup of the tractor, load sensing steering valves, priority valve, flow boosters can be used. In this statement, the steering system with a single-cylinder front axle with double-acting and double-rod in the middle and using an open-center, reaction-free steering valve, which has its own independent pump that is driven by the engine and therefore does not require priority or load sensitivity, will be taken as reference (Fig. 1). ).