Manila Railroad 45 class

The most notable feature of the 45 class was that the roof of the locomotive extends to the tender. It provided cover against rainfall, a necessity for engineers shoveling coal from the tender to the engine. Some first batch engines were not designed this way however, and would instead borrow the tenders used by the earlier 37-class.^[6] Like all steam locomotives of the era, it had a buffer and chain type of railway coupling, the standard that would be adopted by the UIC later on.^[6] It also featured a Walschaerts valve gear which gained popularity among Asia-Pacific railroad operators.^[1]

The design was praised by the Manila Railroad for its efficient fuel usage, as well as its ease of maintenance.^[1] It will influence the design of later, larger steam locomotives. The Baldwin-built 140 class of 4-6-2 Pacifics used the design made by Porter.^[7]

The first group of locomotives, numbered 45-54 entered service in 1919 with the locomotives stored in Caloocan yards. Satisfied with its design, the Manila Railroad ordered 10 more locomotives and were built by Porter in 1921.^[2] The locomotives were used throughout the system during the 1920s and the 1930s. After World War II, several units survived unlike its bigger peers such as the 140 class and the 200 class. The remaining units continued pulling trains after the war until the 1950s.^[1]

The switch to diesel power made the Manila Railroad to retire its steam locomotive fleet starting in 1954. The Porters were the first to be relegated from mainline service to short-distance maintenance trains carrying ballast, and served as such as late as 1980s.^[1] One of the locomotives; No. 62 would later be on static display as props for movies such as the 1989 Japanese war film Harimao. The last units were scrapped in the 1990s and were never preserved.