Formation of the hitch weight of wheeled tractors for tillage technologies

The research goal is to substantiate the level and distribution of the hitch weight by the axes of high-powered wheeled tractors as part of tillage units of different types and technological purposes. Taking into account the normative requirements for the main parameter determining the nominal traction force and class of the tractor are taken operational, full ballast mass and the coordinates of the center which corresponds to the weight  and the center of gravity which determine the normal static reactions of the soil to the front and rear wheels. The increase of the tractor hitch weight up to (0.05–0.16)GE and its redistribution along the axes in the working run mode caused by the influence of the normal component of traction resistance and the weight of the working machine is classified as additional ballasting. The condition for adapting 4k4b wheeled tractors to the working run mode with at the optimum center of gravity (mass) as a part of trailed, semi-mounted and mounted tillage units is to provision of weight distribution on the axes in static, respectively: (0.55–0.56); (0.59–0.60) and (0.63–0.65). In the range typical for 4k4a tractors, for these types of units, the center of gravity is respectively: (0.40–0.44); (0.42–0.46) and (0.46–0.50). The increase of soil response to the wheels and the hitch weight of tractors, due to the influence of the normal component of traction resistance and the weight of the working machine, reaches 5.5-16%. When forming the operational weight of tractors, it is advisable to take as a basis the equivalent - specific gravity in statics 58,0 kg/kW with an axle distribution of 0.60/0.40 for (4k4b) (0.40–0.45) and (4k4a) for (0.40–0.45). These parameters ensure the use of units in speed intervals that are rational for technology, reduce the mass of removable ballast to a minimum, significantly reducing the time and money spent on preparation for operation.