Determining the tractor’s nominal traction force

Goal. To formulate at the conceptual and methodological levels the determination of the nominal tractive effort (NTE) of a tractor based on a theoretical analysis of its change under the linear nature of the slippage of the drives of a wheeled power vehicle. Methods. Theoretical studies were conducted using the foundations of higher mathematics and the theory of tractor traction dynamics, which consider the dependence of the traction efficiency and the linear law of the slippage of the drives of a wheeled power vehicle on the traction effort realized by it. Calculations were performed in the Mathcad 15.0 software environment. Results. Under the linear nature of the dependence of the slippage of the drives of a wheeled tractor on the traction effort, its traction efficiency may not be optimal. For the tractor KhTZ-17021 with the wheel formula 4K4b, the maximum value of this parameter is 0.642 and is achieved at a traction force of 33 kN and a maximum slip of 15%. The optimal value of the tractor’s traction efficiency is 0.646, but it is realized at a slip of its engines of 17.6%, which exceeds the maximum permissible value, and therefore is unacceptable. Conclusions. When the traction force of the power tool at the maximum level of its traction efficiency (Pkrh) does not exceed the traction force at the maximum slip (Pkrd), the nominal traction force of the tractor (Pkrn) on any agrotechnical background is equal to the arithmetic mean between these forces, and the tolerance interval for NTE is calculated by the expression Pkrn = 0.5×[( Pkrh + Pkrd) ± (Pkrh–Pkrd)]. Otherwise, the nominal tractive effort of the tractor is determined by the tractive effort at the maximum slippage of its engines, and the tolerance interval for the NTE is calculated by the equation Pkrn = (0.9…1.0)×Pkrd.