Engineering and construction of 6 tunnel locomotives 45 ton hydrostatic diesel engine was defined in Mapna Locomotive Company (MLC) due to the need of the Islamic Republic Of Iran for internalization of tunnel locomotives for subway projects. The design and supply of key components and assemblies were done using the internal power of Mapna engineers locomotive engineers and domestic suppliers as well as utilizing up-to-date European knowledge and equipment. The final product of this project has been used to meet the needs of the employer and to operate under conditions in the ongoing subway infrastructure projects in Iran. For example, this product is currently used in some cities of Iran such as Mashhad and Tabriz, which are undergoing urban metro construction operations.