Class MT-1/MT-2 (Locobase 230)

Data from 1936 Union Pacific locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive collection.

Originally delivered with Young valve gear and greater superheater surface, the only Mountains the Union Pacific ran were upgraded in the 1930s with Walschaerts valve gear and one-piece cast-steel frames; it is this upgrade that's shown in the data. Locomotives 7850-7864 were leased to the Los Angeles & Salt Lake.

When Railway and Locomotive Engineering's July 1922 issue featured this greyhound, the author commented on the "lightness of parts" that went into the design. He notes that the 2-8-2s then in service were not equal to the task of maintaining an average speed of 37 mph over the 484 miles between Ogden, Utah and Cheyenne, Wyoming; their drivers were simiply too small to meet the higher speed requirements.

In addition, "It may not be generally known that there are grades west of Cheyenne in the Wyoming division of long distances running as high as 1.55 per cent on the westbound, and 1.14 per cent grades on the eastbound operation. Six through passenger trains pass over this region daily"

Then RA's reporter noted the catch in using a 4-8-2 layout with taller drivers: "The only difficulty in introducing the mountain type of locomotive was in the recognized fact that the weight should not exceed 345.000 Ibs., for while the railroad, as is well known, is double tracked and of the most substantial construction, the numerous bridges, viaducts and other structures are not calculated to meet the requirements of heavier motive power than the weight referred to."

The result was a success: "[7000] has not been approached in point of design where boiler capacity in relation to weight is considered, and has only been made possible by a close comparison with other types where weights are known and by thorough tests of individual parts and material in order to ascertain what was possible as the looked for accomplishment, looking towards a general introduction of the mountain type of locomotive, if the success of the experiment should prove beyond controversy."

The diagrams show that many were fitted with a streamliner casing and bullet nosecap. They also reveal the 16" piston valves. Wes Barris's steamlocomotive.com site (http://www.steamlocomotive.com/colored/#brown, last accessed 27 February 2010 ) shows a more extensive streamlining of 7002. The purpose of streamlining 7002 (and Pacific 2906, described in Locobase 6612) was to substitute for the early diesels when they were unable to pull the heavy, all-Pullman Forty-Niner trains 5 times a month between Chicago and San Francisco in 1938-1941 to help celebrate the Golden Gate Exposition. Like the 2906, the UP fitted Timken roller bearings on every engine axle and in the rods as well. Weight grew to 257,500 lb on the drivers and 382,500 lb for the engine overall.

Like that of the 2906, the casing adopted fell short of aesthetic triumph to perhaps a greater degree than the installation on the 2906. The most dominant color was chocolate brown (called Leaf Brown by the UP), accented by the Armour Yellow stripe on the bluntly curved nose (it had yellow whiskers as well), Scarlet trim above yellow on the valences that underlay the running boards, lazy-oval cab windows, and the trademark yellow-with-red stripe tender. The overall effect was to reduce the mighty Mountain and its 6-axle tender to a Lionel nightmare.