Abstract
	The application and design of products (e.g. spur gears) is nowadays considerably simplified and accelerated by using different design software. Mentioned software enable to make an exact product with required accuracy, witch could in configurations of mechanical drawing because of fabrication or gave application to the case solution by FEM. The FEM method is the most enhanced up-to-date method suitable for strain and stress investigation. It is several programmes for solving the cases by FEM, but the first condition for it is the most accuracy constructing of product. The programme COSMOS/M or ANSYS enable depict the products at its background. But lonely depicting of product (e.g. spur gears) because of complicated form of tooth flank is too difficult and time consuming. This aspect by preferable course is transporting of tooth flank geometry prepared with help by CAD-2D or CAD-3D (AutoCAD, Pro/Engineer, etc.). The article hints a comparison of availability mentioned programmes used to the designing of spur gears. In the both cases the big attention was given at the most precisely construction of involute and smooth fillet parts of the tooth side by basic rack. Forasmuch as in the practise mainly are used the tooth gears with modifiable tooth fashions, depicting of them by CAD-2D is not excessively suitable. This point view by the most suitable method for preparing of spur gears is using programme CAD-3D, in our case programme Pro/Engineer, witch enables by designing of gear to use relations between dimensions. This enables to prepare a dimension various range of spur gears of required accuracy in brief. In the conclusion of paper are showed developments of strains by FEM on specifically case of spur gear by transferring of geometrical data of them from Pro/Engineer in COSMOS/M.