In the presented paper there is presented description of discredited calculation model and course of calculations of design connected with project of secondaty tillage set of new generation for simultaneous soil tillage and sowing with the use of universal drill. The design was elaborated with the use ofcomputer system CAD-3D that allowed to build virtual solid models of machine. Strength calculations were carried out with the use of computer system of the "high range" group. The results of simulation and computer calculations served for the choice of optimal shapes and materials to build prototype of the machine.