Imperial Government Railways Articulated Locomotives in Japan

Class 4600/9750 (Locobase 10974)

Data from [], and 1922 Locomotive Cyclopedia, p.1016. See also Akira Saito, "A Summary of Overview of Japan's Modern Steam Locomotives", based on his May 2000 Rail Magazine article and available on the web from 2004 at [] . (Thanks to Alexander Blessing for his 15 October 2024 email correcting the adhesion wheelbase. NB: for articulateds, this figure is always smaller than the "driving wheelbase.") Schenectady works numbers were 51946-51969 in 1912.

Alco's home plant in Schenectady, NY, turned out this batch of Mallets in 1912 as part of a big JGR splurge on compound articulated locomotives that were hoped to "solve a big bottle neck at Hakone-pass, the most important trunk line." Alco had already supplied six 0-4-4-0 Mallets, a small design Saito dismissed as training vehicles.

He speculated that Yasujiro Shima, the JGR's well-known motive power exponent, wouldn't have accepted "imports that had not been technically evaluated" by JGR's locomotive engineers." But Shima was in Germany at the time and couldn't counter "aggressive" sales tactics on the part of three major locomotive builders--Baldwin, Henschel, and Alco. Indeed, "importation circumstances were really vague. The engineer had neither knowledge of it nor its prospect for the future."

One key failing was the lack of a leading truck, which would have reduced flange wear. Unlike South African efforts to improve Mallet and later Garratt articulated locomotives, Saito wrote, Japanese Mallets were "neither remodeled nor developed into a new design, and ended their lives in less than 20 years."

(The 0-4-4-0s mentioned above later received a leading axles and were reclassified as Class 9020 2-4-4-0s. The modification only marginally extended their working careers, which ended in 1925.)

Class 4600/9800 (Locobase 4419)

Data from narrowmind.railfan.net, which reproduces a plate from AE Durrant's The Mallet Locomotive. See also data from Record of Recent Construction #91 (Baldwin Locomotive Works, 1918), p.16-17; and DeGolyer, Volume 49, pp. 214+. (Thanks to Alexander Blessing for his 15 October 2024 email correcting the adhesion wheelbase. NB: for articulateds, this figure is always smaller than the "driving wheelbase.") Works numbers were 51946-51969.

Durrant's comment: "Baldwin's ...superheated Mallet for Japan did not inspire a general adoption of articulated power for the prevailing mountainous terrain." The photograph shows a surprisingly racy-looking design with relatively tall drivers outlined in white and a high-pitched boiler.

Baldwin noted that the locomotive was designed for grades as steep as 1 in 30 (3.3%) and curves as tight as 400 ft radius.

See Locobase 10974 (Alco's Mallet batch of 1912) for Akira Saito's May 2000 criticism of the original procurements of 0-6-6-0s from Baldwin (here), Henschel (Locobase 7622), and Alco (Locobase 10974).

Class 4600/9850 (Locobase 7622)

Data from Robert Garbe, "C+C Mallet-Heissdampf-Verbundlokmotive fur die japanishen Staatsbahnen" in Die Dampflokomotiven der Gegenwart (Berlin: Julius Springer, 1920), pp.513-515 (title translates, perhaps, to "Locomotives of Today".). See also the Kotsu Hakubutsukan Japanese transportation museum site [], last accessed 3 July 2006; and "Class 9850" on the A Profile of

Japanese Steam Locomotives website at [], last accessed 26 October 2024. (Thanks to Alexander Blessing for his 15 October 2024 email correcting the adhesion wheelbase. NB: for articulateds, this figure is always smaller than the "driving wheelbase.") Works numbers were 11657-11668 in 1912.

In Locobase 4419, Locobase reports on the Baldwin batch of Mallets delivered to Japan in 1912. This entry covers the Henschel order. All four cylinders used piston valves to supply steam.

The Profile website supplies considerable detail on the class's history: "These Mallet engines were not only on Hakone pass on the Tokaido line, but also they were used on the Otsu - Kyoto on the Tokaido line, Kuroiso - Shirakawa on the Tohoku line, Nagano - Naoetsu on the Shinetsu line and Kameyama - Kamo on the Kansai line for freight trains and pusher operations. A few Mallet engines temporarily ran between Yubari and Iwamizawa on the Muroran line Hokkaido.

And in the end, almost all Mallet engines were finally concentrated at Yamakita depot for Hakone pass banker during 1922.

These Mallets operated briefly on the Tokaido main line until the 9600-class 2-8-0s (Locobase 3816) replaced them.

Yet the Mallet's considerable size did not result in significant power, the Profile notes, and maintaining the four-cylinder compound setup required "extra effort". 9600-class 2-8-0s (Locobase 3816) replaced the engines in main-line helper service. They were then relegated to branch-line service until the 1930s.

See Locobase 10974 (Alco's Mallet batch of 1912) for Akira Saito's May 2000 criticism of the original procurements of 0-6-6-0s from Baldwin (Locobase 4419), Henschel (here), and Alco (Locobase 10974).