The book presents practical examples of troubleshooting tools applied in real technological processes. The content is useful for technicians, engineers, or maintenance professionals involved in setting up technical systems and reliable operation of rotary machines. The book presents various proactive maintenance methods, exploring how they can be applied to enhance the reliability and efficiency of technical systems. The importance of technical diagnostics is highlighted, offering valuable insights into the process of identifying and analyzing potential issues. The measurement and assessment of vibrations in technical systems are examined. Moreover, the book covers assessing the condition of systems through the study of friction, lubrication, and wear. The application of technical diagnostics tools in reductors’ test operation is also detailed. In the concluding section, readers will find a thoughtful synthesis of the key concepts discussed throughout the book.