The aim of this book is to disseminate this new test method to a wider audience. It deals briefly with the general maintenance problems of machines, the guiding principles of modernization and of technical condition tests, including technical diagnostics, with the instruments of vibrometry and in more detail with the testing of a few characteristic machine elements and main components, as well as the organization of machine control. The causes of imbalance, including the principle, methods, and machines of balancing are also discussed from the practical aspect. [p] The book will be a useful aid to specialists dealing with the modernization of maintenance, and those in charge of plant maintenance in general.