In 1928 in Poznań H. Cegielski Manufacturing Company started the production of locomotive without tender designed for agglomeration traffic. It was the first completely Polish construction created on the basis of documentation prepared under engineer Gustav Brylinga by a team of engineers Stanisław Domaniewski, Stanisław Cwynar and Witold Mrażek. To 1933 122 locomotives of this type were built; in the course of production various changes were implemented such as: a reinforced frame, welded water compartments and experimental valve gear system of engineer Wiktor Wysuch (OKl27-112). The suspension system on leaf springs allowed adaptation to axle load of 16 or 18 t. Steam locomotive was designed for use in suburban traffic: Warsaw, Gdańsk and Katowice. In the postwar period the Polish State Railways used 95 locomotives of this type. In the final period of exploitation, despite a significant diversification of the Polish State Railways network the locomotives could be found most frequently in the area of Silesian and Central District State Railways Management (DOKP). Locomotive OKl27-26 (former OKl27-61) preserved on the museum exhibition ended its service in Białystok depot and was deleted from the inventory on 22 November 1978.