Union Pacific FEF series

The Union Pacific FEF series consists of 45 4-8-4 "Northern" steam locomotives built by the American Locomotive Company (ALCO) between 1937 and 1944 and operated by the Union Pacific Railroad until 1959. Like other Union Pacific steam classes, the acronym comes from the first letter of the spelling of its wheel arrangement: Four Eight Four.

The final steam locomotives built for the Union Pacific, the FEFs represented the apex of dual-service steam locomotive development in the United States, as funds and research were thereafter concentrated into the development of diesel-electric locomotives. Designed to burn coal, they were converted to run on fuel oil in 1946. They pulled a variety of passenger trains, such as the Overland Limited, Los Angeles Limited, Portland Rose and Challenger, until diesel-electric locomotives took over passenger service. Many FEF series locomotives were reassigned to freight service during the last years of their careers.

Four FEF series locomotives survive, including No. 844, which remains in operational condition and runs in excursion service. The 844 is one of the Union Pacific's oldest serving locomotives and the only steam locomotive never retired by a North American Class I railroad.

Origins
In the late 1930s, rising trainloads started to exceed the limits of the 4-8-2s that were the mainstay of 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 as the train was waiting for rescue, a telegram was sent to ALCO in Schenectady seeking something better. The result was the FEF series, a superb class of locomotives that could run at 100 mph and produce between 4,000 and 5,000 drawbar horsepower. They would run about 14,000 miles a month.

Models
The FEF series consisted of three classes of steam locomotives: FEF-1, FEF-2, and FEF-3.

FEF-1
The first 20 locomotives, numbered 800–819, were delivered by ALCO in 1937. As a whole, they followed the simplest possible arrangement of two outside cylinders, as had the Northumbrian locomotives 108 years earlier. Fitting ALCO's lateral motion devices to the leading coupled wheels eased the negotiation of curves. UP resisted most of the complicated accessories on many other locomotives, resulting in an elegant, uncluttered appearance. Despite frequently running faster than 100 mph, the forces and stresses on the coupling and connecting rods were kept within acceptable limits. There were many reports of the class reaching the design limit of 110 mph.

FEF-2


Dubbed FEF-2, the second batch of 15 was delivered in 1939. Their improvements included larger cylinders, better tractive effort, smoke deflectors on the sides of the smokebox, and driving wheels that were three inches wider in diameter. The biggest change was the replacement of the 12-wheeled tender with a 14-wheeled "pedestal" or "centipede" tender. FEF-2, UP 833 has been tied to claims to have hit the classes' max speed of 120 mph; but was not officially recorded due to the speed violating Union Pacific's corporate rules.

FEF-3
Except for the use of some substitute materials, the final batch of 10 were nearly identical to the FEF-2. After World War II, coal supplies were limited by a series of strikes. To safeguard operations, UP converted the 800s to burn oil, and fitted a 6000 usgal tank 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. Like many of the "late era" steam locomotives, their final design was cut short by the advent of diesel locomotives, the new monarchs of the rails. A former manager of the Union Pacific Steam Program said, "Although it is stated that the UP FEF Series were designed to safely operate at 120 mph, no one really knows how fast the final 4-8-4 could go. The last FEF-3 was actually never retired."

Surviving examples
Four FEF series locomotives survive. No. 814 (FEF-1) and No. 833 (FEF-2) are on static display. No. 844 (FEF-3) has remained operational and is used in excursion service. No. 838 (FEF-3) is used solely as a source of spare parts for No. 844.