A drive unit (10) for an inspection vehicle which can be used on ferromagnetic bases (19), especially in generators, which drive unit includes a motor-powered crawler track (18) and also magnetic devices for holding the drive unit (10) on the base (19). An improved insensitivity to uneven spots in the base is achieved by the crawler track (18), in the region where it bears upon the base (19), being guided via inner, spring-mounted running wheels (12), and by the magnetic devices being integrated in the running wheels (12).