Studies on the Applicability of Empirical Equation for Estimating the Skid of the Wheel (1)

Tests of Two Wheel Tractor on Hilly Land

Abstract

It was observed from the tests of single wheel apparatus in door, that the theoretical equation on side force derived by E. Fiala agreed well with the experimental results. According to this equation, the side force of wheel under skid was estimated by the followings: the frictional resistance at the contact surface of wheel, rolling resistance, drawbar load, side slip angle and a factor of cornering coefficient.
A factor of cornering coefficient (C), which could not be measured directly, was one important parameter in appraisal of skid the empirical equation of C on farm was obtained from the experimental results of single wheel.
In this paper, the applicability of the empirical equation was discussed on the basis of experimental results in hilly land, using the two wheel tractor with agricultural tire, double tire and steellugged wheel (attached with the non-skid plates), respectively.
Main results were as follows:
(1) On the rolling wheel of agricultural tire and double tire, the estimated valus of C calculated from the empirical equation agreed well with the experimental values at 10 degree of the inclination angle of land, but not at 20 degree because of the slippage among soils.
On the steel-lugged wheel, the experimental values were larger than the estimated values due to the effect of non-skid plates.
(2) On the driving wheel of agricultural tire and double tire, the estimated values of C agreed well with the experimental values under the small drawbar load. It did not agree however under the large drawber load, and the side slip angle became large due to the slippage among soils.
(3) At the large inclination angle of land, steellugged wheel was better than the others because of the increase of the frictional resistance to the contact surface, preventing the tractor from skid.
(4) From these results, the empirical equation of C agreed well with the experimental results for the skid except the effect of slippage among soils.