蒸気機関車Mクラス (2-6-8-0)は、グレートノーザン鉄道でも変則的な2-6-8-0という軸配置の関節型蒸気機関車です。実物は、1910年にM-1クラスとしてボールドウィン社で複式マレー（後ろのシリンダーで使った蒸気を再加熱して前のシリンダーで再使用するもの）で製造されました。その後、1926-27年に4つのシリンダーに同時に蒸気を送る単式に自社工場で改造されてM-2クラスとなり、更にその後、キャブ前面が斜めになっているスポーツタイプキャブとバンダービルトテンダー、プレート先輪（それまではスポーク）を装備してM-3クラスとなっています。このクラスの機関車は、メサビ鉱山からの鉄鉱石運搬やモンタナ州のマリアス峠越え等に活躍しました。晩年は、1929-31年に全35両のうち22両がO-7クラス(2-8-2)に改造されましたが、残った13両のＭクラスは、この1973号機も含めてモンタナ州の支線等で1950年代まで使用されました。
今般、gngoatに細かい番号入りで詳細な歴史が投稿されましたので、転載します。なお、小職が持っているＨＯモデルＭ－３（写真）については、このブログの2005年4月20日版もご参照ください。
Railroad History #143, published by the Railway & Locomotive History, Autumn, 1980 & reprinted in 1989 by the GNRHS, by Kenneth R. Middleton & Norman C. Keyes, Jr.
Per this publication, the M-2's were simplified in 1926 - 1927 from the M-1's, which were compound 2-6-8-0's. They kept this wheel arrangement until 1929 -31 when, #'s 1950, 1952 - 1962, 1964, 1966, 1969 - 1971, 1975, 1976, 1978, 1979 & 1982 were rebuilt into O - 7's, 2-8-2's with renumbering per the referenced publication. The M-1's were originally built in 1909 - 1910.
All the other M - 2's stayed 2-6-8-0's until they were scrapped starting in 1949 with #1984. #'s 1951 & 1963 were scrapped in 1950. #'s 1972, 1974 & 1980 were scrapped in 1951. #'s 1965, 1967, 1968 & 1981 were scrapped in 1953. #'s 1973 & 1983 were scrapped in 1954.
Per what I've read, these M - 2's were good for branchlines because of their light axle loading & they had some decent tractive effort, 95,500 #'s.
After World War II, the O - 7's were rebuilt into O - 8's.
今般、gngoatに細かい番号入りで詳細な歴史が投稿されましたので、転載します。なお、小職が持っているＨＯモデルＭ－３（写真）については、このブログの2005年4月20日版もご参照ください。
Railroad History #143, published by the Railway & Locomotive History, Autumn, 1980 & reprinted in 1989 by the GNRHS, by Kenneth R. Middleton & Norman C. Keyes, Jr.
Per this publication, the M-2's were simplified in 1926 - 1927 from the M-1's, which were compound 2-6-8-0's. They kept this wheel arrangement until 1929 -31 when, #'s 1950, 1952 - 1962, 1964, 1966, 1969 - 1971, 1975, 1976, 1978, 1979 & 1982 were rebuilt into O - 7's, 2-8-2's with renumbering per the referenced publication. The M-1's were originally built in 1909 - 1910.
All the other M - 2's stayed 2-6-8-0's until they were scrapped starting in 1949 with #1984. #'s 1951 & 1963 were scrapped in 1950. #'s 1972, 1974 & 1980 were scrapped in 1951. #'s 1965, 1967, 1968 & 1981 were scrapped in 1953. #'s 1973 & 1983 were scrapped in 1954.
Per what I've read, these M - 2's were good for branchlines because of their light axle loading & they had some decent tractive effort, 95,500 #'s.
After World War II, the O - 7's were rebuilt into O - 8's.
