Lateral force applied to a wheeled machine on turning. The lateral force calls forth unstability of tractors and propelled farm machines on turnings. At the curvilinear motion the lateral force results from the centrifugal force and in the case of speed variation it results from the force of inertia (Figure 1).
A computational experiment is used to research the variation of the lateral force and the factors having an effect upon it. A classic tractor with the front steerable wheels is considered as a simple planar solid. The lateral force applied to the tractor is computed at two manoeuvres: at turning and in the case of changing the lane. The steerable wheel turning angle is considered to vary sinusoidally (Figure 2).
The results of the computation indicate, that in case of movement with the constant speed the lateral force varies respectively to variation of the steerable wheels turning angle. Acceleration increases the lateral force while the maximum of the lateral force is postponed with respect to the maximum of the steerable wheel turning angle. In the case of decelerated movement the lateral force decreases and obtains its maximum with anticipation when compared to the maximum of the steerable wheel angle.
The steerable wheel turning angle and the speed of tractor have the most essential effect upon the lateral force (Figures 3,4 and 6). The constructive and exploitation parameters, like mass, axle base, lateral co-ordinate of the centre of gravity also have effect on the lateral force.
The lateral force applied to the tractor consists of three components (Formulae 11 and 12). The component F1 of the lateral force caused by the centrifugal force makes up the domi-nating part of the lateral force. In the case of low speed the component F2 of the lateral force caused by the variation of the speed may appear comparable with the component F1 caused by the centrifugal force (Figure 7).