The Northern type locomotives on the Union Pacific were built by Alco Schenectady Works in 3 classes between August 1937 and December 1944. The first class, designated FEF-1, for Four Eight Four, comprised numbers 800-819. Fitted with 77-inch drivers and a 300-pound boiler pressure, UP was impressed by their performance and took delivery of 15 additional 4-8-4 locomotives in Aug-Oct 1939, numbers 820-834. These locomotives were equipped with 80-inch drivers and larger 14-wheel centipede style tenders with a 23,500 gallon capacity and were class FEF-2. In Dec 1944, 10 additional 4-8-4 locomotives were delivered, these equipped with low-backpressure double stacks, numbered 835-844, and designated FEF-3. All three classes developed 63,800 lbs of tractive effort.
Throughout their service careers multiple modifications were made, including conversion to oil, feedwater heater systems, addition of smoke lifters (designated Wind Wings on UP drawings) and a Mars light, and replacement of stacks from singles to doubles and even triple stacks. UP 844, the final steam locomotive delivered to UP, has been in continuous service on Union Pacific since it was built in 1944; renumbered from UP 844 to UP 8444 between June 1962 and June 1989.
In this production, BLI is modeling the FEF-2 Class and also the #844 with its Mars Light. Notable features are listed below:
Accurately modeled FEF-2 double stack and triple stack - prototypically accurate for each road number
Accurately modeled turret casing
Individual side rods
Centipede-style oil tenders with finely detailed oil inserts. #844 has the Heritage Fleet containment dam, other road numbers do not.
Options for Worthington and Sellers FWH
Wind Wings on models where prototypically accurate
Prototypically accurate FEF-2 front end and pilot (except #844)
Walschaerts Valve Gear
#844 as it ran from 1989-2013, with Mars Light