It is ever more necessary that equipment, systems, and installations operate as long as possible without failures. And when failures occur they must be as short as possible. This is when maintenance becomes actively important through the obligation of giving a quick response, efficiently, and economically. To be successful at these types of responses, it is fundamental to continually improve the practices used in maintenance activities. This paper focuses on the use of the TPM methodology combined with a few lean thinking tools in order to optimize the availability of a critical production line in a company which produces mechanical components and gearboxes for the automotive industry. To measure the success of the implemented actions and to compare the final results with the initial situation, a few indicators were used: Overall Equipment Effectiveness (OEE), Mean Time Between Failures (MTBF) and Mean Time to Repair (MTTR).