Influência dos parâmetros de pneu e solo na tração

Dedicated to the 80th Anniversary of Prof. Radoš Řezníček

Influence of soil and tire parameters on traction
M. Schreiber1, H.D. Kutzbach2
1 2

AGCO GmbH, Product Marketing Manager (MP), Marktoberdorf, Germany University of Hohenheim, Department of Agricultural Engineering, Stuttgart, Germany

Abstract: The drawbar pull, travel reduction (slip), and rolling resistance are the main criteria to describe the traction behaviour of off road vehicles. Besides the engine performance, the drawbar pull is influenced by the traction conditions such as soil and the tire parameters. These traction conditions have to be described by a limited number of parameters which can be easily determined. Empirical equations were used to analyse roughly 850 traction curves measured and published by Steinkampf. As a result, the important parameters to describe the traction conditions are three tire parameters (radius, width, inflation pressure) and five soil parameters (soil cover, upper soil strength, lower soil strength, clay content, moisture content). These parameters with relative values between 0 and 100% are used to establish the equations for the traction prediction. Main steps to achieve this goal are the extension of the traction slip equation by a linear term of slip, and the description of this curve by 4 meaningful characteristic coefficients: the x- and y-coordinates of the κ-maximum (σκmax, κmax), the y-axis intercept ρe, and the gradient of κ at zero slip (κ’(0)). Keywords: tire; traction; wheel-slip

The tire and soil parameters influence the traction performance of farm tractor tires (Schreiber 2006). In 1956, Bekker laid the foundation for scientific investigation of soil-wheel interaction mechanism and extended his model in the following years (Bekker 1956, 1960). Numerous attempts followed to quantify the soil-traction device interaction in order to set up models for the traction prediction (Upadhyaya & Wulfsohn 1990). Wismer and Luth (1973) used the Cone