Faculty of Forestry and Wood Technology, University of Zagreb
Abstract
This article deals with the assessment of traction properties of tyres on forest grounds. The research was carried out on skid trails located in pine stands. The tested grounds were different due to the cover of the soil and its mechanical properties. The study also deals with the evaluation of ways to improve traction by reducing the inflation pressure and using the tyre chain. The research was carried out using a specialized traction test stand for two tyres (9.5–24 and 400/55–22.5) different in width and tread pattern. The studies showed significant effect of ground conditions on traction. As a result of changes in the ground conditions, the values of drawbar force, rolling resistance and tractive efficiency were altered by 25%, 23% and 6%, respectively. The higher values of the drawbar force and tractive efficiency on all tested trails were obtained for 400/55–22.5 tyre. Both the use of tyre chains and the reduction of inflation pressure resulted in the increase in drawbar force and tractive efficiency. A better way to improve traction properties was the reduction of the tyre inflation pressure, which caused the increase in drawbar force and tractive efficiency. The use of tyre chains caused an increase in drawbar force over the entire slip range, while an increase in tractive efficiency has only been shown for the slip larger than 15%
