In 1936–1939 Baldwin Locomotive Works built nine 0-10-2 steam locomotives for the Union Railroad. Since these were the only locomotives ever built in the United States to this wheel arrangement of 0 pilot wheels, 10 driving wheels and 2 trailing wheels, the name “Union” was applied to this type. The Union Railroad was a transfer line located in Allegheny County, Pennsylvania that was owned by U.S. Steel which served steel plants in the area while connecting with six trunk line railroads.
The railroad needed to get rid of helper locomotives on the grades that the roads 2-8-0 Consolidation class couldn’t cope with. However, the railroad turntable's were not long enough for a 2-10-2 locomotive. So the decision came down to selecting the 0-10-2 because a leading truck’s stability was not required since they were to be operated at low speed. No pilot wheels and no trailing wheels were typical for railroad yard switchers, so what happened here in effect was the creation of the worlds largest and most powerful switcher. It was, as mentioned, unique in the USA.
The use of ten driving wheels spread the enormous weight and maximized traction. The trailing truck supported the large firebox and combustion chamber necessary to heat all the water in the enormous boiler. To raise the tractive effort (pulling power) of the locomotive to the max, the Union Road ordered a front mounted tender truck booster engine, a rare device. (The tender is the car behind the locomotive that holds the coal and water.) The locomotive was rated for 90,900 lbs of tractive effort, the tender engine for 17,150 lbs making for a whopping total of 108,050 lbs. This machine could move anything attached to its coupler’s.
After 10 years of fine service, in 1949 the Union Railroad dieselized and these locomotives became surplus. The good news for these 9 was U.S. Steel not only owned the Union Railroad but the Duluth, Missabe and Iron Range in Minnesota. So off they went shoving ore jennies (small heavy-duty iron ore hopper cars) in upland Minnesota for another 11 years or so.
At the end of steam on the DM&IR, 8 of the locomotives were scrapped but 1 was saved and was brought home to Pennsylvania. In a wonderful sense of history, the locomotive now sits painted for both railroads, one on each side of the tender. Presently, while outside exposed to harmful elements, it is beautifully, even lovingly, preserved with other pertinent artifacts of local Greensville railroading history.
My only consternation is that the good people of Greensville have placed so many railroad signals and bushes around it, you cannot get a full view of the locomotive. The effect is that the locomotive becomes a gigantic lawn ornament.
But be that as it may, it is glorious that URR 304/DM&IR 604 exists so that we may all see the biggest steam locomotive switcher in the world.