Theory of motion controllability of a wheel machine-tractor aggregate

Abstract

Aim. To obtain analytically new dependencies, determining the indicator of motion controllability of a wheel machine-tractor aggregate, taking into consideration external forces, constructive and kinematic parameters of the aggregate while the latter moves in the transport mode. Methods. The methods of tractor and vehicle theories, theoretical mechanics, the theory of dynamic stability, and methods of numeric computer calculations. Results. A new theory of motion controllability of a wheel machine-tractor aggregate during its non-linear mo- tion along the surface of the soil at an angle to the horizontal was elaborated. The analytic expressions for the determination of the actual indicator of aggregate controllability, including force and constructive parameters of a machine-tractor aggregate, affecting this indicator in the longitudinal-vertical plane were made. The ana- lytic expressions were obtained for the transport mode of the aggregate movement. The conditions, in which cross slips of the directive wheels of the tractor with implements in the longitudinal plane were analytically considered for the fi rst time. The analytic expressions for the determination of the required indicator of the controllability of the machine-tractor aggregate in the longitudinal plane, excluding any possibility of a cross slip of the aggregate while turning its directive wheels at a certain angle, were defi ned. Conclusions. Computer calculations demonstrated that during the non-linear movement along the surface of the soil at an angle of 12 ° to the horizontal the wheel machine-tractor aggregate will be controllable only if the wheel turning angles for the tractor with implements do not exceed 9 ° . In case of the working motion of this aggregate along the slope, its controllability is preserved on condition that the turning angle of directive wheels does not exceed 11 ° . It was established that the controllability of the wheel machine-tractor aggregate is determined by the actual λ d and required λ о indicators of controllability, which take into consideration the values of the vertical load on the directive wheels of the power source, the possibility of their turn in the longitudinal plane, and the pull during the deviation from rectilinear motion when it moves along the surface at an angle to the horizontal.