Class P-1 (Locobase 3074)

Designed with a conical Belpaire boiler and relatively huge 16" piston valves.

These Mountains ran the hilly sections of the Great Northern's route, including a section between Cut Bank and Whitefish, Montana that had 1.8% eastbound grades. According to Railway Age (14 Dec 1914), introducing the Mountains had eliminated the need for a helper engine and had increased speeds to 20 mph.

That speed and the 15 mph over the Cascades' 2.2% grade proved too slow for passenger service, however, and the 4-8-2s were put into freight service. In 1928 they became Q-2 2-10-2 freight hogs, the only time, Drury (1993) notes, that a Mountain was converted to another wheel arrangement; see Locobase 8114.

Class P-2 (Locobase 206)

Data from GN locomotive diagram found on Ben Ringnalda's http://www.greatnorthernempire.net/images/GNP_2523Diagram.jpg (viewed 18 August 2003). Works numbers were (in order of delivery) 57000-57002, 57084-57085, 57182-57190 in September 1923; 57256-57258, 57339, 57012, 57253, 57341-57347 in October.

http://www.ddg.com/LIS/InfoDesignF98/rdoyle/empire/articles/orienttrain.html (18 August 2003) presents the Great Northern Railway Historical Society's Reference Sheet No. 217 (June 1994), which notes that the P-2s were designed to meet the demand of the Great Northern's Oriental Limited.Piston valves were smaller than those of the earlier P-1s, measuring 14" in diameter. Everything else about these engines -- grate, boiler, superheat ratio, adhesion weight, firetube diameter -- grew in response to the demand. The firebox heating surface included 40 sq ft of arch tubes and 95 sq ft in the combustion chamber.

When they went into service, P-2's initially were limited to a 50-mph top speed, but still managed 4,800 miles/month with single crews. 10 of the 28 engines in this class were coal burners; these handled the Oriental east of Cut Bank, Montana. The other 18 oil burners operated farther west. Tonnage rating was 10-12 heavyweight passenger cars up Walton Hill (1.8% ruling grade) at 18 mph..

Drury (1993) comments that these were successful passenger-haulers and were considered by many to have the best-looking Great Northern engine class. He adds (195) "Theire over-square cylinders were unusual; yet more unusual for Great Northern was the conventional radial-stay fireboxes [as opposed to Belpaire]."