Union Pacific 9000 Class

Infobox Locomotive
name=Union Pacific 9000 Class
powertype=Steam

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caption=The prototype, UP 9000, as presrved at the Los Angeles County Fairplex in Pomona, California.
gauge=4 ft 8½ in (1435 mm)
whytetype=4-12-2
uicclass=2F1
railroad=Union Pacific
railroadclass = 9000
numinclass=88
builddate=1926-1930
builder=American Locomotive Company
length=102 ft 7 in (31,267 mm)
locotenderweight=782,000 lb (354.8 t)
weightondrivers=355,000 lb (161.1 t)
tractiveeffort=96,650 lbf (43,852 kg)
cylindersize=Outside (2): 27 in bore × 32 in stroke (685 mm × 813 mm); Inside (1): 27 in bore × 31 in stroke (685 mm × 787 mm)
cylindercount=3
boilerpressure=220 lbf/in² (15.5 kg/cm²)
driversize=67 in (1701 mm) diameter
tenderc

The Union Pacific 9000 Class was a class of 88 4-12-2 steam locomotives built by Alco between 1926 and 1930.

Origins

Union Pacific's crossing of the continental had steep grades, and train tonnages were constantly increasing. During the 1920s, trains were being handled by 2-8-8-0 Mallet compounds and 2-10-2s. Speeds above 25mph were not then possible with the Mallet arrangement, whilst 2-10-2s had limited adhesion. To enable a 12-coupled locomotive to negotiate curves, the 9000s were provided with Alco's new lateral motion device.

References

*cite book
last = Hollingsworth
first = Brian
title = The Illustrated Dictionary of Trains of the World
year = 2000
publisher = Salamander Books Ltd.
locaion = London
isbn = 1-84065-177-6
* [http://www.steamlocomotive.com/3cylinder/index.shtml Three Cylnder Steam locomtives] maintained by Wes Barris