The article is devoted to the search for a mathematical model convenient for practical calculations to determine the critical value of the angle of gradient for the tractor-mounted heavy tilther. It shows the existing mathematical model, which is then refined based on the stiffness of the elastic tractor wheels and their vertical reactions offset. Three methods of solving the resulting equations are analyzed, upon which the optimal one is chosen. As a result, a simple and convenient in practice mathematical model to determine the critical value of the angle of gradient for the tractor-mounted implement is obtained. The analysis of the calculation results showed that depending on the operating conditions and the weight of the tractor counterweight, the differences between the results calculated using the traditional and refined models can reach more than 4 degrees, which is very important to ensure the hill climbing safety.

The article provides analytical dependences for calculating such important parameters of the cutter for soil cultivation as the number of revolutions of the shaft with the knives fixed on it, the indicator of the kinematic regime, feed to the knife, as well as the power consumed by the cutter. Taking into account the results of research by other authors, numerical calculations were carried out. The following are the results of experimental studies of the process of milling the soil, carried out using a prototype machine. The torque on the drive shaft of the machine was determined using the strain gauge method. To determine the rotational speed of the cutter shaft, optical sensors were used, the translational speed of the machine was determined based on the processing of signals from a speed meter driven by the support wheel of the machine. As a result, it was found that the milling cutter with the values of the parameters determined theoretically provides high quality soil cultivation. The calculated values of the power consumed by the cutter are in good agreement with the experimental results.

The article is devoted to the improvement of the tiller designed to operate on rocky soils. The elements of the interaction theory between the tiller work tools and the rocks in the soil are presented. Two cases of the machine blade hitting a rock were analyzed. The improved machine design containing safety devices and a digital alarm system that reports the operator on the safety device response is proposed. Safety devices are installed on each machine section, which reduces the area of untilled soil during their response. A contactless sensor is installed above each section, the signal from which is analyzed by a measuring device according to a special algorithm. Rational values for the main parameters of the tiller section fuses are determined and the time of the section blade hit a rock is studied. The improved tiller sample testing of 2020 and 2021 on rocky soils in the mountainous terrain proved the efficiency of the proposed design.