Mechanical Considerations on the Fluctuation of Drawbar Pull of a Rigid wheel on Sandy Ground

Abstract

Drawbar pull of a traveling wheel varies with certain amplitude in a stationary state, even though the traveling speed is so slow that the inertia force is negligible. Averaged values of the mechanical quantities are used as characteristic values of traveling performance, and such small fluctuation is usually neglected. The properties of fluctuation of drawbar pull and so on are mechanically examined by the traveling tests of a rigid wheel on sandy ground so that the fluctuation is important phenomena to clarify the traveling performance and to control machine operations. A soil reaction vector acted on the wheel moves back and forth on the contact surface with some extent of width. It is clarified that such behavior is similar to the walking motion of a man's leg. The horizontal distance from the intersecting point of the vector to the vertical center line of the shaft increases with the decrease of drawbar pull, conversely decreases with the increase of drawbar pull. There is a negative correlation between the horizontal distance and the drawbar pull. It is shown that the phenomena can be represented by the balance equation of torque.