Union Pacific 9000 Class
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Union Pacific 9000-series | ||
---|---|---|
Factor of adh. 3.66 | |
Career | |
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Operators | Union Pacific Railroad |
Class | UP-1 through UP-5 |
Numbers | 9000–9087 |
Retired | 1953–1956 |
Preserved | One preserved (No. 9000), remainder scrapped |
Disposition | No. 9000 on static display at the RailGiants Train Museum |
The Union Pacific Railroad 9000 Class was a class of 88 steam locomotives, built by ALCO for the Union Pacific between 1926 and 1930.
Wheel arrangement
The Union Pacific 9000 class was the only class of steam locomotives with a
Other equivalent classifications are:
AAR wheel arrangement: 2-F-1
Russian classification: 2-6-1
History
These locomotives were used to increase the speed of freight trains in flat country, and were fairly successful, but had very high maintenance requirements, largely because of their use of an inside third cylinder driving the cranked second driving axle between the frames. There was no inside valve gear, however. ALCO had obtained permission to use the conjugated valve gear invented in the UK by Sir Nigel Gresley, who was the chief mechanical engineer of the London and North Eastern Railway. This system used two hinged levers connected to the outer cylinder's valves to operate the inner cylinder's valve. The 9000 class locomotives were the largest to use Gresley gears.
Between 1934 and 1940, eight of the first fifteen locomotives had their Gresley gear removed and were converted to a "double Walschaerts" valve gear, which utilized a double eccentric (return) crank and second link on the right side (similar to the gear Baldwin used on its three-cylinder experimental compound 4-10-2
During design, the third and fourth driving axles were planned to be "blind" (flangeless) in order to improve curve handling, but ALCO's lateral motion devices on the first and sixth axles (which allowed the axles to slide up to two inches to the side) made this unnecessary. They had the longest rigid wheelbase in North America, and the longest in the world until the Soviet Union built their AA20 4-14-4 locomotive in 1934. The trailing truck carried the same axle load as the drivers, which was unusual.
There has been debate as to whether the first driving axle of the 4-12-2 was cranked to provide clearance for the
Year | Quantity | Class | Alco order number | Alco serial numbers | Union Pacific Number | Notes |
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1926 | 1 | UP-1 | B-1684 | 66544 | Union Pacific 9000 | Preserved |
1926 | 14 | UP-2 | B-1684 | 67024–67037 | Union Pacific 9001–9014 | 9004 to OWR&N 9708, then back to UP 9004 |
1928 | 15 | UP-3 | B-1706 | 67581–67595 | Union Pacific 9015–9029 | |
1928 | 8 | UP-3 | B-1708 | 67596–67603 | Oregon-Washington Railroad and Navigation Company 9700–9707 |
to Union Pacific 9055–9062 |
1929 | 25 | UP-4 | S-1646 | 67944–67986 | Union Pacific 9030–9054 | |
1930 | 15 | UP-5 | S-1701 | 68490–68504 | Union Pacific 9063–9077 | to Oregon Short Line 9500–9514 |
1930 | 10 | UP-5 | S-1701 | 68505–68514 | Union Pacific 9078–9087 | |
Total | 88 |
Only one example has survived into preservation. Union Pacific 9000, the prototype of the class, is preserved at the Railway and Locomotive Historical Society's museum at the Los Angeles County Fairplex in Pomona, California. It received new boiler paint in 2006-2007.
References
- Drury, George H. (1993), Guide to North American Steam Locomotives, Waukesha, Wisconsin: Kalmbach Publishing Company, pp. 397–398, 404, LCCN 93041472
- Hollingsworth, Brian (2000). The Illustrated Dictionary of Trains of the World. London: Salamander Books Ltd. ISBN 1-84065-177-6.
- Kratville, William W.; Bush, John E. (1990). The Union Pacific Type, Vol. 1. Omaha, Nebraska: Barnhart Press. LCCN 90082171.
- Kratville, William W.; Bush, John E. (1995). The Union Pacific Type, Vol. 2. Omaha, Nebraska: Barnhart Press. LCCN 90082171.
- Westcott, Linn H. (1960). Model Railroader Cyclopedia - Volume 1: Steam Locomotives. Kalmbach Books. ISBN 0-89024-001-9.