The book describes the design of the excavator E-505 and replaceable working equipment, indicating the changes introduced by the plant in the design of excavators E-505 various releases and E-505A (E-651). Analysis of the causes of malfunctions and breakdowns of excavators during operation, methods of their prevention, as well as brief information on field repairs. The book is designed for workers of excavator teams and linear mechanics working on the repair and operation of excavators. It can also serve as a teaching tool when studying an excavator in excavator courses.