This paper analyzes the maintenance of a two-stage deep pump gearbox reducer (swing type ĐĐ-160) and the following overhaul procedures, from the planning phase to completion and the final report. In general, the swing ĐĐ-160 and its parts are described. The gearbox reducer and its main parts and technical data are explained in the table view, and the gearbox reducer is shown in the assembled condition and sectional drawing. Genuine maintenance of the gearbox reducer and proper repair preparation and repair itself ensure a safe and reliable operation of the swing. The maintenance of the gearbox reducer consists of corrective maintenance, which in almost all cases is carried out in the workshop, and preventive maintenance where lubrication of the bearings is carried out with oil and grease. The analysis includes a schedule of maintenance and overhaul activities, organization, manufacturer’s list with recommended repair and maintenance steps, technological and operational documentation, procurement of required spare parts, workforce plan, maintenance information system (SAP), repairs and overhaul of the gear reducer. All these steps are important for the high quality and reliable maintenance and execution of planned overhaul works.