The book describes the designs of the most common narrow gauge steam locomotives of the "factory type" (750 mm): series 157, 159, PT-4, Kch-4, Gr and others. The thermal calculation of the steam locomotive boiler and data on testing steam locomotives are given. The book is designed for engineering and technical workers related to the operation of narrow gauge steam locomotives. At the moment, it is a bibliographic rarity given the circulation of 8,000 copies. and year of publication. In addition, the literature on the design of narrow gauge steam locomotives in itself was not so massive due to the small number of machines themselves compared to wide gauge steam locomotives.