The traveling performance of rigid wheels on sand stratum is measured using two kinds of surface material, i.e., steel and steel coated with rubber. A new method for measuring the displacement of soil beneath the wheel has been developed using small polyester film markers. The trajectories of soil particles beneath the wheels are approximated by an exponential function and the fluctuations in the drawbar pull are represented by a sinusoidal function. The amplitude and basic wavelength of the fluctuation in the drawbar pull are discussed for both types of wheels.

〔Keywords〕rigid wheel, soil deformation, strain distribution, drawbar pull, fluctuation