Union Pacific 9000
Southern California Chapter
Railway and Locomotive Historical Society
Union Pacific locomotive number 9000 was donated to the
the Union Pacific in May of 1956. Designated a 4-12-2, or Union
type, it is the largest steam locomotive built on a rigid frame and it
a wheelbase of over 30 feet. Its 12 drive wheels are powered by
massive cylinders, one of which is located between the frame -
transmitting its power through a crankshaft on the second driver
axle. The other two cylinders are connected to the conventional
main and side rods which
attach at the third driver. Number 9000 was built for fast, heavy
service and it is the only survivor of a group of 88 similar
built for the Union Pacific. It saw continuous service for almost
years and was used mainly between Green River, Wyoming and Council
Shortening the piston stroke of the center cylinder by one inch (which connected to the second set of drivers) along with increasing the separation between drivers one and two (by almost 18"), increasing the separation between the first pair of drivers and the cylinder saddle and inclining the center piston assembly to an angle where the forward end was 9" above horizontal, allowed the center piston rod, wrist pin assembly and main rod to clear the first driver axle during all movement, thereby avoiding the need to put a clearance bend or "crank" in the axle of the first driver set.
The original integrated feedwater heater/pump assembly was the Worthington 4½ BL-2. Changing to the 5-SA allowed the weight of the components to be distributed along the length of the locomotive and and not concentrated in one spot and on one side.
The 9000 retained its spoked drivers during most its career. However, Boxpok wheels were placed on the main driving axles (#2 and #3) on of many of the series.
Orders UP-3 through UP-5 received American Throttle Company's front end (superheater) throttles in place of the steam dome throttles on earlier Nines.
The 9000 was delivered with an Elvin
Stoker, which also quickly proved to be inadequate. Duplex D-3
stokers were applied to locomotives starting in the UP-3 order, but
noisy and took up significant space in the small cab. Duplex
gradually began replacing the D-3's.
UP 9000 Photo Gallery
Listen to a 9000
The following audio clips of UP-9009 were recorded by Howard
Fogg in 1954 in Nebraska.
|Page last revised - 07/01/2003|