Union Pacific Class FEF-3

The Union Pacific FEF-3 is the third and final batch of the FEF Series (FEF meaning, "four-eight-four") which consisted of ten 4-8-4 "Northern" type steam locomotives built by the American Locomotive Company (ALCO) in 1944 for the Union Pacific Railroad (UP). They were assigned road numbers 835 through 844.
== Origins ==
During the late 1930s, the rising trainloads started to exceed the limits of the 4-8-2 that were the mainstay of the UP passenger operations. One day, in 1937, with UP President William Jeffer's business car in the rear, a "7000" Class 4-8-2 demonstrated the lack of steaming power inherent in the type. Even when the train was waiting for rescue, a telegram was sent to ALCO in Schenectady seeking something better. The result was a superb class of 45 locomotives known as the FEF Series that could run at 100 mph and produce between 4,000 and 5,000 drawbar horsepower. They also ran about 14,000 miles a month.
The first twenty locomotives were delivered by ALCO in 1937 and were classified as the FEF-1 with the later 25 being classified as the FEF-2 and FEF-3. The "800"s, as they were sometimes known, as a whole followed the simplest possible arrangement of only having two outside cylinders. Fitting ALCO's lateral motion devices to the leading coupled wheels eased the negotiation of curves. Complicated accessories often spoiled the basic simplicity of so many US locomotives, but UP resisted most of them, resulting in an elegant, uncluttered appearance. Despite frequently moving at speeds over 100 mph (161 km/h), the forces and stresses on the coupling and connecting rods were kept within acceptable limits. There were thus excellent results, and there were many reports of the class reaching the design limit of 110 mph (177 km/h).
The second batch of fifteen was delivered in 1939. These had several improvements, including larger cylinders, better tractive effort, smoke deflectors on the sides of the smokebox, and the driving wheel diameter was increased by three inches. The greatest change, however, was the provision of a fourteen wheeled "pedestal" or "centipede" tender, in place of the twelve wheeled ones of the first twenty locomotives. 
The final batch of ten were nearly identical to the FEF-2. After World War II, coal supplies were affected by a series of strikes. In order to safeguard operations, UP converted the 800s to oil burning, and a 6,000 US gallons (23,000 l; 5,000 imp gal) tank was fitted in the bunker space. Otherwise, few modifications were needed to ensure years of mainline service. These were the last steam locomotives delivered for the UP. 
==Preservation==
Of the 10 that were built only two of the class have survived into preservation, Nos. 838 and 844, with 838 serving a source of spare parts for No. 844 which is still in service to this day.
== Stock list ==
Loco No.	Image	Build date(s)	Retirement date(s)	Status
835 	 	1944 	July 1962 	Scrapped
836 	 	1944 	- 	Scrapped
837 	 	1944 	- 	Scrapped
838 	 	December 1944	July 1962 	Remains as a source of spare parts for No. 844
839 	 	1944 	- 	Scrapped
840 	 	1944 	- 	Scrapped
841 	 	1944 	1957 	Scrapped
842 	 	1944 	- 	Scrapped
843 	 	1944 	1957 	Scrapped
844 	 	December 1944	Never retired 	Still in service
Category:4-8-4 steam locomotives
Category:4-8-4 locomotives
Category:Union Pacific FEF Series
Category:Steam locomotives
Category:Union Pacific locomotives
Category:Tender locomotives
Category:ALCO locomotives
Category:Built in 1944
Category:American steam locomotives
Category:Locomotives
Category:American locomotives
Category:United States
Category:Eight-coupled locomotives
Category:Standard gauge locomotives
Category:Standard gauge locomotives of the United States