Ten Wheelers and the Northern Pacific S-4's

Engine 1364 is one of more than 16,000 steam engines built to the general category known as 'ten wheelers'. They were called ten wheelers because they had a wheel arrangement of 4-6-0, with four wheels on the front (pilot) truck, and six driving wheels. There was no rear truck under the cab. This locomotive design was one of the most popular and versatile ever built.  Construction of the ten wheelers engines began about 1850, and the last United States ten wheelers were built in the late 1920's. The British were building ten wheelers long after that.

The Class S-4 was the last of the ten wheelers built for the NP.  The Baldwin Locomotive Works built forty  S-4's numbered 1350-1389.  The 1364 was built in May of 1902 and assigned the serial number 20421.  The S-4's were built for mainlinefreight service west of Livingston, MT, but they were also used in passenger service.  As newer more powerful locomotives were built, the S-4 class locomotives were used more in local and branchline service.  Most were active to the end of the steam era in the 1950's.  In addition to the 1364, three other NP S-4 engines still exist in parks in Pasco, WA, (NP 1354), Helena, MT, (NP 1382) and Missoula, MT (NP 1356).

S-4 class steamers were originally built with compound Vauclain cylinders and had 63 inch drivers. They operated on 200 lb. of boiler pressure. The empty locomotive weighed 174,100 pounds but increased to 184,850 ready to run.  Add 103,00 pounds for the tender ready to operate and the total weight was 287,850 pounds. Using coal as a fuel, 31,320 pounds of tractive effort were created.  During World War I, the compound cylinders were removed and Schmidt superheaters were added to improve performance and lessen operating costs. The resulting engines were among the most successful steam engines on the NP. 

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