The JGR Class 3920 (originally the JGR Class AH) was a 2-6-0RT Mogul-type side tank Abt rack rail steam locomotive operated by the Japanese Government Railways from 1895 to 1917.
History[]
The Class 3920 was an early steam locomotive operated in Japan. The type was manufactured for the JGR, with two locomotives manufactured by Beyer, Peacock and Company in the United Kingdom and delivered in 1895. The locomotives were classified the Class AH on the JGR and numbered 168 and 169; the locomotives were then reclassified as the Class C2 and renumbered 505 and 506. The locomotives were ordered out of necessity as the JGR had required a dedicated rack rail locomotive to scale the 66.7‰ (1/15 gradient) gradients of the Usui Pass, as well as to exploit foreign employees in Meiji Japan; the only rack rail locomotives at the time were German locomotives manufactured by Maschinenfabrik Esslingen, and the British wanted to find a way to refine and surpass the capabilities of the Esslingen locomotives. The design of the locomotives was overseen by Francis Henry Trevithick (a son of Richard Trevithick), with the locomotives having a distinctive T-shaped smokestack with a long probe extending to the rear of the locomotive in an attempt to reduce the soot problems as seen with the previous Class AD locomotives; this worked in practice but reduced the locomotive's efficiency.
The locomotives were reclassified as the Class 3920 in 1909 when a formal rule regarding standardized classification of locomotives was enacted; the locomotives were thus renumbered 3920 and 3921. When the section for the Usui Pass was electrified, the Class 3920s were no longer needed there and as such they were used to haul normal freight trains. The locomotives were retired in 1917. No Class 3920s survive, although it appears that 3921 was not actually scrapped after retirement and was damaged during the Great Kanto Earthquake.
