Studies on the Steering Characteristics of Tractor (I)

Performance of Turning Motion

Abstract

As one of the fundamental characteristics to evaluate the controllability and the stability of the travelling tractors on the ground, the cornering characteristics were discussed based on the experimental results obtained from the stational circular turning tests under the fixed steering angle.
(1) On the turning motions of the tractor, the turning radius increases according with the increase of the travelling speed in any case of the weight distributions on the front and the rear axle.
(2) The cornering powers, namely the relation between the side slip angles and the cornering forces, varies with the distributions of the weight on the front and the rear axle, and with the types of the tires, but not with the front wheel angles. In general, the tractors are equipped with different tires on the front and the rear wheel, and the cornering powers of the front wheels are less than the rear wheels. Therefore, it seems that the high degree of the understeering characteristics of the tractor is caused by the differences of the cornering powers of the front and the rear wheel tires.
(3) The cornering coefficient is nearly constant at any distribution of the weights on the axles. Therefore, as the fundamental characteristics value to evaluate the cornering characteristics of the tractors, the cornering coefficients are available.
(4) The tire inflation pressure of the tractor of the tractor on the ground, has little influence on the cornering characteristics. It is considered that the soil deformations under the tires are caused.
(5) The maximum values of the cornering force are defined with the coefficient of friction between the tire and the ground. Hence, in the case of the tractor with the steering front wheels of which cornering coefficients are smaller than the driven rear wheels, the side skid should be discussed in the way of limitation of understeering characteristics, on the directional stability of the tractor.