The turning gear, code P51325-23, is an essential auxiliary device in the MAN L21/31 engine that allows safe, controlled rotation of the crankshaft during inspection, maintenance, and startup procedures. Powered by a 3 x 440V electric system, the turning gear ensures precise positioning of engine components, preventing damage and enabling thorough checks of pistons, valves, and bearings. Its reliability is critical for both operational safety and ease of service.