39676 – SNCB/NMBS Class 202 Diesel Locomotive
The units also known as "Round Noses", "Potato Bug", or "Bulldogs" were based on the famous American F7/FP7 diesel locomotives of Electro-Motive Division (EMD of General Motors (GM). Yet the direct prototype of the "Round Noses" came not from the USA but from Australia, since there a rather European clearance gauge predominated, and a six-axle bi-directional variant was built by Australian licensees. The result of this at the start of the Fifties was the European license variation AA16 at GM/EMD. Its body rode on two three-axle Flexicoil trucks with drive to all wheel sets or only to the outer wheel sets. The power transmission was done with the proven GM drive train with DC power transmission whereby the main generator mounted on the diesel motor fed electrical power to the axle-suspended traction motors on the powered wheel sets. The slow running, water-cooled, two-stroke cycle type GM 567 diesel motor could be controlled in eight speed steps. Ultimately, the rather "archaic" diesel electric system based on the GM regular production models built in large numbers in the Thirties and Forties no long met the latest level of the technology, but it had proven itself in thousands of locomotives.
In 1954, the SNCB ordered 40 "Round Noses" from the Belgian sub-licensee AFB, which were delivered in three classes between 1955 and 1957: class 202 (202.001-013 & 015-018, 1,720 hp, 120 km/h / 75 mph, with steam heating), class 203 (203.001-019, 1,720 hp, 120 km/h / 75 mph, without steam heating), class 204 (204.001-004, 1,900 hp, 140 km/h / 87 mph, with steam heating). Since the Luxembourg Railways (CFL) urgently needed powerful road diesels, four of the units originally intended for Belgium were transferred to the CFL in April of 1955 as 1601-1604, and four additional locomotives (202.015-018) were ordered for the SNCB, which were admittedly already converted in 1957 into 204.005-008. Starting January 1, 1971 the class designations changed to 52, 53, and 54. Between 1978 and 1993, the "round noses" were done away with on 34 locomotives, because they were equipped with completely new, so-called "floating" cabs ("Cabine flottante"). In addition in the Eighties, there were several conversions of class 53 locomotives into class 52 and vice versa. Currently there are only two round nosed SNCB units preserved, SNCB museum locomotive 5404 and the 5204 cared for by the association "Patrimine Ferroviaire et Tourisme" (PFT).