Northern Pacific 2-10-0 "Decapod" Locomotives in the USA

Class M (Locobase 800)

Data from [] (19 June 2003) and from a 1944 Northern Pacific Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also DeGolyer, Volume 13, p. 121; and "Decapod Locomotives", Engineering (London), Volume 44 (29 July 1887), p. 117. Works numbers were 8168-8169 in August 1886.

Quoting a Northern Pacific "Tell Tale" article from its February 1950 issue, the site says that these two decapods were intended for heavy freight service in the Cascade mountains and were the heaviest locomotives in the world at the time they entered service.

Engineering reported that the pair had been "a surprise to the mechanical department of the system, owing to the unexpected ease with which they pass round the sharpest curve." This echoed a letter sent by the NP's Superintendent of Motive Power G W Cushing in January 1887 to Philadelphia, who wrote that the Ms could go "anywhere, either on bad track or curves, that an eight-wheeled engine could go." (reported in "Stampede Pass Switchback and Tunnel", Railroad Gazette, Volume 19 (23 December 1887), pp. 824-825.

At the time the NP was building switchbacks to work trains over the Cascades and the Ms would provide helper service. The Stampede tunnel, which would reduce maximum grades to 116 ft/mile (2.2%), was expected by the end of 1888.

The pair were later renumbered 1-2 and converted to yard switchers.