Field Evaluation of Skidder Tire Tractive Performance

Abstract

Tractive performance was evaluated under field conditions for a cable skidder equipped with seven combinations of bias-ply tires and one set of radial-ply tires. Traction performance variables and maximum pulling capacity were measured on forested and haul road surfaces. Little difference in maximum pulling capacity was found among the four widest tire combinations tested: 6850-32s, dual 6843-25s, dual 30.5L-32s, all bias-ply construction, and 6868-25 radial-ply tires. Single 28L-26s and 6843-25s operated at two different inflation pressures had the lowest maximum pulling capacity, but the results for the 6843-25s appeared to be biased because of wet site conditions. A net traction-slip model was presented and its parameters estimated using regression. Results indicated that the model accounted for a large proportion of the variability in the net traction/slip data but tended to overpredict net traction at low and high slip and underpredict at intermediate slip. Tire width did not appear to influence the model parameters consistently. The test surface, however, did affect bias-ply tire performance, with the field surface tending to lower the rate at which net traction ratio approached its maximum value, indicating lower tractive efficiency. This was not true for the radial-ply tires, which appeared to be as efficient on either surface.