Oregon Short Line / Union Pacific 4-8-0 "Mastodon" Locomotives in the USA

Class 900 (Locobase 3945)

Data from "Twelve-Wheel Freight Locomotive for the Oregon Short Line Railroad", Railroad Gazette, Volume XXXII [32], No 10 (9 March 1900), p. 149.

A subsidiary of the Union Pacific, the OSL had several main lines out from western Wyoming into Idaho and Oregon. On the rugged grades of such terrain a low-drivered twelve-wheeler fit right in.

According to the RG for 20 April, one of these engines would pull a 1,650-1,700-ton train over a ruling grade of 0.9% from Pocatello to Dubois, where two Consolidations pushed from the rear to get the train up a 2 1/2% grade to Monida.

A compilation of Cooke locomotives by B.Rumary (25 Kingscombe, Gurney Slade, Radstock, BA3 4TH, ENGLAND) and supplied to Locobase by Allen Stanley in March 2004 shows the following works numbers:

2469-2471 (October 1899); road 900-903

2475 (October 1899); road 904

2495-2496 (November 1899); road 905-906

The class was vacated beginning in March 1926 (1854) and ending in November 1928 with 1853 and 1855.

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Class Mastodon / TW-57 (Locobase 1224)

Data from an 1899 Brooks catalogue.

Brooks builder info from B.Rumary, 25 Kingscombe, Gurney Slade, Radstock, BA3 4TH, ENGLAND and Jeremy Lambert as supplied by Allen Stanley in March 2004. Works numbers 3211-3218 in May 1899. (Another seven 4-8-0s were classed as TW-55 and numbered 1850-1856.)

Illustration shows a high-mounted "Improved Belpaire" boiler with characteristic squared firebox (with 23 sq ft of arch pipes) and short funnel-shaped stack. Data from a Railroad Gazette article of 1900 (Vol XXXII, No. 18) shows slightly different grate and heating surface areas. Utah Rails points out that this class and the class of Ten-wheelers, were the only UP locomotives to have been fitted with Belpaire fireboxes.

Renumbered 1800-1807 later on. Retirements came in 1925 (1800-1804) and 1926 (1805-1807).