Union Pacific 5511

Union Pacific 5511 is a 2-10-2 “Santa Fe” type steam locomotive built by the Baldwin Locomotive Works in September 1923 as part of the Union Pacific Railroad's TTT-6 class. While other railroads referred to this wheel arrangement as the “Santa Fe” type, Union Pacific simply categorized it by its wheel configuration—2-10-2—and class. It is the last surviving 2-10-2 of 144 units operated by the UP from 1917 to the end of steam in 1959, and the only complete UP steam locomotive equipped with Young valve gear.

Union Pacific 5511
No. 5511 in Brady, Nebraska, being towed to Silvis, Illinois, in November 2022
Type and origin Power type Steam Builder Baldwin Locomotive Works Serial number 56999 Build date September 1923
Specifications Configuration: ​  • Whyte 2-10-2  • UIC 1'E1 Driver dia. 63 in (1,600 mm) Wheelbase 79.37 ft (24.19 m) ​  • Engine 41.42 ft (12.62 m)  • Drivers 22.50 ft (6.86 m) Axle load 58,000 lb (26,000 kg) Adhesive weight 288,700 lb (131,000 kg) Loco weight 362,200 lb (164,300 kg) Tender weight 231,000 lb (105,000 kg) Total weight 539,200 lb (244,600 kg) Fuel type Fuel oil Fuel capacity 5,200 US gal (20,000 L; 4,300 imp gal) Water cap. 12,000 US gal (45,000 L; 10,000 imp gal) Firebox: ​  • Grate area 84 sq ft (7.8 m2) Boiler pressure 200 psi (1,400 kPa) Feedwater heater Coffin C-87 Heating surface: ​  • Firebox 341 sq ft (31.7 m2) Cylinders Two, outside Cylinder size 29.5 in × 30 in (750 mm × 760 mm) Valve gear Young Loco brake Air brakes
Performance figures Maximum speed 45 mph (72 km/h) Tractive effort 70,449 lb (31,955 kg) Factor of adh. 4.10
Career Operators Union Pacific Railroad Class UP TTT-6 Number in class 12 of 25 Numbers UP 5511 Retired 1956 Current owner Railroading Heritage of Midwest America Disposition Undergoing restoration to operating condition

The locomotive ran in revenue service until being withdrawn in 1956. Afterwards, it remained in storage in the UP's roundhouse in Cheyenne, Wyoming. In April 2022, Union Pacific announced that No. 5511 was among several pieces of equipment to be donated to Railroad Heritage of Midwest America (RRHMA) in Silvis, Illinois, with plans to rebuild No. 5511 for operational purposes once Challenger No. 3985 is rebuilt. As of 2025, both Nos. 3985 and 5511 are still undergoing operational restoration.^[1]

History

Revenue service

Between 1917 and 1924, the Union Pacific Railroad was facing new operational challenges. As freight traffic increased and the railroad expanded across the rugged terrain of the American West especially through the Wasatch Mountain and Sherman Hill, UP needed more powerful locomotives capable of handling long, heavy trains over steep grades. By the 1910s, the Mallet compound articulateds were powerful but complex, and the traditional 2-8-0 “Consolidation” types were becoming outdated. UP engineers, in collaboration with the Baldwin Locomotive Works, began looking for a solution that could provide strong tractive effort, reliable performance, and a simpler mechanical layout. Union Pacific purchased 144 2-10-2 "Santa Fe" types, divided into classes TTT-1 through TTT-7. American Locomotive Company (ALCO) built 18, Baldwin Locomotive Works built 88 and Lima Locomotive Works built 37. Despite the divided classes, all of the UP 2-10-2s had the same cylinder dimensions, driving wheel diameter and boiler pressure.^[2]

As traffic grew, these locomotives became workhorses for UP’s freight division. No. 5511 was the twelfth member of twenty-five TTT-6's to be built in 1923. It was initially assigned to pull heavy freight trains over the steep grades of the Wasatch Mountain Range between Ogden, Utah and Green River, Wyoming. With the eventual introduction of the 4-6-6-4 "Challengers", which would be more capable of climbing steep grades than the 2-10-2s, No. 5511 was reassigned to pull long freight trains across the Great Plains in Wyoming, Nebraska and Iowa. Sometimes, the locomotive would also be used to help push other freight trains up Sherman Hill.

By the end of 1956, No. 5511 was removed from the UP's active list before it was used as a stationary boiler in Ogden and then Green River. In December 1958, No. 5511 was filmed to appear in Last of the Giants, a UP film that mostly featured the railroad's 4-8-8-4 "Big Boys". During filming, because the locomotive was no longer operational, it was coupled to a string of freight cars with an EMD diesel locomotive coupled to the other side to push, while No. 5511 would have burning tires inside the smokebox. After filming was finished, the locomotive was sent to Cheyenne, where its piston rods were cut and it was scheduled to be scrapped with the rest of the UP's 2-10-2s. However, an unknown employee had ordered the locomotive to be held for preservation due to its movie appearance. As a result, the locomotive was moved from Green River to Cheyenne Wy and stored inside the UP's roundhouse in Cheyenne. ^[3]

Preservation

By the end of the 1960s, No. 5511 became the only 2-10-2 locomotive from the UP to be preserved. The locomotive was repainted for a cleaner appearance and stored inside the UP's Cheyenne Roundhouse for the next six decades. During that time, the locomotive was repainted and moved onto a turntable to be displayed for a National Railway Historical Society (NRHS) convention. Subsequently, the locomotive was stored without boiler jacketing. Over the years, there was debate about 5511’s condition. Some claimed it was in poor shape, stripped of cab components and lacking a boiler inspection. Others reported that UP’s steam team had evaluated the boiler and found it to be in surprisingly restorable condition. Still, many considered 5511 a poor candidate for operation. It was designed for slow, heavy freight—its large cylinders and small drivers limiting it to about 45 mph. It had a long wheelbase, friction bearings, and a small tender, all seen as disadvantages. Some hoped it would be sent to a museum; others believed it missed its chance when UP traded Big Boy 4014 to Cheyenne and gave RailGiants an operational diesel in return. Many felt 5511 would have been the perfect trade—a rare, one-of-a-kind engine with Young valve gear, ideal for display and preservation. ^[4]

Restoration

In April 2022, the UP announced that No. 5511 would be among four locomotives to be donated to the Railroading Heritage of Midwest America (RRHMA), with the others being 4-6-6-4 No. 3985, EMD DDA40X "Centennial" No. 6936 and an EMD E9 B unit. Several other pieces of rolling stock from the heritage fleet were also included in the donation.^[5] The RRHMA has plans to rebuild both 5511 and 3985 back to operation.^[6] On May 13, 2022, RRHMA launched a fundraiser to raise enough money for the restoration of the Nos. 5511 and 3985 steam locomotives.^[7] On September 14, 2022, No. 5511 was moved from the Cheyenne roundhouse and around the yard for testing, behind Big Boy No. 4014. This marked the first time 5511 was moved out of the roundhouse since 1970. ^[8] In November of that same year, UP moved No. 5511 and the rest of the donated equipment to the RRHMA's large shop facility in Silvis, Illinois.^[9] No. 5511 is undergoing operational restoration alongside 3985.

In January 2023, 5511's smokebox was opened for the first time since storage, and crews began drying out the boiler in preparation for tube removal. In February 2023, RRHMA removed petticoat pipe and stack tops to access internal boiler components. In March 2023, RRHMA Crews removed the superheaters and began milling the boiler pipes. In April 2023, all boiler tubes were removed, and the interior was marked for cleaning and inspection. In July 2023, the firebrick and safety valves were removed for cleaning and refurbishment. In September 2023 the pistons, valves, rings, and piston rods were removed from the cylinders. Needle-scaling prep began to clean out heavy carbon and tire residue from filming Last of the Giants. In December 2023, the crossheads, crosshead guides, and rods were removed and sent to Alex Beams’ shop in Newton for restoration. New firebox sheets, piping, and decking arrived and were staged for installation.

In February of 2024, the stacks, dry riser pipes, branch pipes, T-pipes, and superheater headers were removed. The boiler was washed ahead of planned flue sheet removal. The heavily corroded dome was shipped to Strasburg for patterning a replacement. In July 2024, RRHMA received a brand-new steam dome fabricated in Strasburg and was installed on 5511. The next phase focused on removing the flue sheets and beginning the replacement of deteriorated boiler sheets. In February 2025, RRHMA began cleaning the mud ring and drilling out defective stay bolts in the firebox. The original firebox sheets were marked to create accurate patterns and address design flaws in the staybolt layout. The mud ring, remaining stay bolts, and damaged firebox and flue sheets were prepped for removal. Meanwhile, damaged piston and valve rods—originally cut in 1959 when the engine was marked for scrapping—were sent to Newton to have new castings made. In April 2025, 5511's whistle, along with 3985's, was returned from Rizzoli Locomotive Works and tested on Jeddo Coal Company No. 85 during a public shop tour. In June 2025, the superheater header plate and dry riser pipe were reinstalled following complete rebuilds. Next, crews will replace the throttle assembly and reattach boiler piping in preparation for steam testing.^[10][11][12]

See also

• Southern Pacific 975
• Southern Pacific 5021