The graduate (diploma) thesis presents the design and 3D modeling of a single-stage reduction drive in the Inventor software. Nowadays, there are more and more different types of reductions drive and designs that are made in a similar way, but none is the same. For each execution that is required and desired, a calculation of all the elements presented in the paper is required. The paper consists of a theoretical and a practical part in which the process of designing reduction drive is described, from budgeting, 3D modeling to the production of technical documentacion. The theoretical part requires a broad knowledge and understanding, and knowlegde of the required machine elements. The theoretical part needs to be made accurately to avoid problems later and it wouldn't come to unwanted breakage and damage when using the reduction drive. The budgeting is necessary to prevent unecessary oversizing of positions, but also safety factors during commissioning. It is important to know the manufacturing process so that it would be possible to make al the necessary machine parts, and later assemble them into the assembly. The practical part of the thesis presents 3D modeling in Inventor. Modeling is performed according to a previously created budget (dimensions and geometry) i models. Finished components and standardized machine elements are used. The electric motor and clutch have already been calculated and defined by their suppliers. All that has to be done is select the appropriate elements and using a STEP model insert them into the assembly for further modeling.