0-4-0 Steam Locomotives in Hungary

Class X/20 (Locobase 1538)

Data from P[eter] M[ichael] Kalla-Bishop, Hungarian Railways (Newton Abbot: David & Charles, 1973); and "MAV 20 sorozat" in Wikipedia (as translated by Google) at [], last accessed 1 October 2025. MAV works numbers were 50-53 in January-February 1882 and 54-58, 37-75 in January-February 1883.

Wikipedia describes the intent of these well-tank engines as providing service on very light-traffic lines where a single locomotive and carriage would be enough. The result was an "omnibus train" rated at 30 kph (18.6 mph) maximum speed, generating 91-92 horsepower using local coal and around 125 hp with foreign fuel. The small engines "proved to be a very excellent design", contended Wikipedia,"and served in all parts of the country.. [they] not only served their original purpose, but also became universal small locomotives on second-class lines.."

Fitting the design to the requirements took some doing, but even so small a power pack easily out-matched the alternatives (animal power or walking). The X is a good example of the essential ubuiquity of the basic steam locomotive concept--scale it up or down and its relative simplicity and adaptability ensured its survival for decades.

With success came the realization that the original Xs proved to be undersized and production ended with 22, wrote Kalla-Bishop.

They then were converted as two-cylinder Von Borries compounds (the very first in Hungary), the principal difference being the installation of a 330 mm diameter low-pressure cylinder. Remarkably, the shops figured out how to modify the original Allan-Trick valve motion to accommodate the different cylinder volumes. Compound operation generated 105-108 hp on local coal.

In this configuration, the X (later 20) class remained in service well into the 20th century.