Union Pacific No. 5511 is a class TTT-6 2-10-2 "Santa Fe" type steam locomotive built by the Baldwin Locomotive Works in September 1923 for the Union Pacific Railroad (UP). 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.
History[]
In the early 20th century, the Union Pacific Railroad (UP) 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 Mountains 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Mallet compound articulateds were powerful but complex, and the traditional 2-8-0 “Consolidation” types were becoming outdated.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.
This need led to the development of the 2-10-2 wheel arrangement, commonly referred to as the “Santa Fe” type on other railroads. Union Pacific, however, categorized its locomotives by function and wheel configuration and designated the class as TTT, short for "Two-Ten-Two". The TTT-6 subclass, to which 5511 belongs, was part of a broader fleet of 144 2-10-2 locomotives ordered by UP between 1917 and the early 1920s. The TTT-6s were among the later batches and were designed for maximum hauling power at lower speeds, making them ideal for steep grades and heavy drag freight. These locomotives were equipped with massive boilers, ten driving wheels, and large tenders for long-haul service. What set 5511 and a few of its sisters apart was the inclusion of the Young valve gear, a compact and efficient alternative to the more common Walschaerts or Baker valve gears. While not widely adopted, the Young gear offered smoother operation and was part of UP’s experimental efforts to optimize performance. Locomotives like 5511 were specifically designed for mountain railroading. Their long wheelbase and numerous driving wheels provided exceptional traction. However, because of their length, they weren’t ideal for high-speed service or tight curves—traits that didn’t matter much on the long, straight, and steep grades between Ogden, Utah, and Green River, Wyoming.
As traffic grew, these locomotives became workhorses for UP’s freight division. No. 5511, built in September 1923, was part of this final and most refined group. It represented decades of steam design evolution, taking lessons from earlier classes while integrating newer components to improve power and efficiency.
Throughout its working life, 5511 hauled heavy freight over the challenging Wasatch Range between Ogden, Utah, and Green River, Wyoming, often serving as a helper locomotive on Sherman Hill and other steep grades. After being retired in 1956, it was stored in Cheyenne, Wyoming. The locomotive gained recognition in the UP-produced film Last of the Giants, which highlighted the evolution of UP's steam locomotives, including the Big Boy class. In the late 1950s, 5511 saw temporary service as a stationary boiler in Ogden and later at the Westvaco plant near Green River, which contributed to its survival during a period of rapid scrapping. By the 1970s, 5511 was then moved and stored at the Cheyenne Roundhouse, where it remained unmodified, never donated or cosmetically altered for display, though it was once repainted and briefly displayed for a National Railway Historical Society (NRHS) convention.
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.
First Restoration[]
On April 28, 2022, Union Pacific officially announced the donation of steam locomotive No. 5511 to the Railroading Heritage of Midwest America (RRHMA) in Silvis, IL alongside UP Challenger No. 3985 and UP DDA40X diesel locomotive No. 6936. After decades of storage at the Cheyenne roundhouse, 5511 was finally set to leave its long-time home. On September 14, 2022, Union Pacific’s Big Boy No. 4014 was fired up to move 5511 around the Cheyenne yard for the first time in over 50 years. This brief movement allowed testing and inspection before the locomotive was prepared for transport. On November 11, 2022, 5511 was towed out of Cheyenne by UP AC44CWCTE No. 5716. After a multi-day journey, it arrived at RRHMA’s former Rock Island Railroad shops in Silvis on November 19, 2022. RRHMA announced plans to fully restore 5511 to operational condition—following the restoration of Challenger 3985.
Disassembly and Inspection – 2023[]
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.[1] In February 2023, RRHMA removed petticoat pipe and stack tops to access internal boiler components.[2]
In March 2023, 5511 dome cover has been removed, as well as the super heaters, which have been carefully stacked and tagged for safe storage while work continues on the rest of the #5511.[3]
In April 2023, No. 5511 has had its boiler flue tubes removed. Over the upcoming months its boiler will be cleaned and prepped for inspection and plans will be made for future repairs.[4]
In July 2023, Work continues on #5511. The fire brick has been removed to facilitate the upcoming inspection of the firebox. The safety valves have been removed and are on their way for rebuilding, and the dynamo (used to generate electricity for headlights and lighting on the locomotive) has been removed as well.[5]
In September 2023, 5511 pistons and rings have been removed for cleaning and inspection. Major needle scaling is being done to the bottom of the front tube sheet and bottom of the smokebox to remove deposits left over when tires were burned in the locomotive for the filming of the Union Pacific movie Last of the Giants in the 1950s.[6]
In December 2023, The main rods and crossheads were removed from #5511, so the faulty piston rods may be removed from the crossheads in preparation for new piston rods. New flue tubes have arrived for both 5511 and UP Challenger #3985. Stay bolt caps from our friends at Strasburg Rail Road have arrived as well. [7]
Major Component Removal – 2024[]
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.[8]
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.[9]
Firebox and Running Gear Work – 2025[]
In February 2025, No. 5511 underwent extensive boiler cleaning and inspection. Volunteers focused on cleaning the mud ring and drilling staybolts inside the firebox. Work also began on dressing the front tube sheet, with similar preparation of the rear tube sheet scheduled to follow. As part of this work, two new staybolts were installed in the firebox. The TTT-6 class design incorporated irregular staybolt spacing on the backhead and door sheet, intended to allow for the optional installation of a mechanical coal stoker in locomotives that were not built as oil burners. However, this design left areas that did not meet the modern boiler safety factor of 4. To address this, restoration crews installed additional staybolts in the open spaces, raising the boiler’s safety factor above the required threshold.[10]
In April 2025, 5511’s whistle, along with 3985’s, was returned from Ruzzoli Locomotive Works and tested on Jeddo Coal Company No. 85 during a public shop tour.[11] [12]
In June 2025, No. 5511 reached another major milestone with the installation of a newly constructed dry pipe and the reinstallation of the superheater header. Due to the limited availability of original drawings for the TTT class locomotives, the dry pipe had to be designed and fabricated from scratch. The original 1920s pipe design used thinner material than current safety standards allow, so a thicker-walled pipe was fabricated to comply with modern FRA requirements. The new pipe was cut to length, fitted with flanges manufactured by Quad City Engineering, heated to 500 °F, pressed into place, and welded at both ends to ensure a steam-tight seal. Seating surfaces were then lapped for proper fit against the front tube sheet. Meanwhile, the superheater header was cleaned, with each Type A superheater seat polished and prepared for reinstallation. After both components were lapped and fitted, the superheater header was lifted into the smokebox and joined to the dry pipe. With this work complete, crews are now preparing the throttle valve for installation following the completion of tube sheet dressing and tube installation.[13]
In September 2025, work on No. 5511 shifted to the locomotive’s appliances, which are essential components for proper operation. Among the first appliances to be addressed were the water column and steam turret, both required for an eventual hydrostatic test of the boiler. These appliances were bead blasted, primed, and painted, while individual valves were lapped into their seats and repacked to ensure steam-tight seals. Hydrostatic testing of auxiliary components has also been carried out. The superheater assemblies from No. 5511 are being tested individually at over 300 PSI to check for leakage. Units identified with leaks are tagged for repair before final installation. Once the superheater testing and repairs are complete, the assemblies will be ready for reinstallation following boiler work.[14]
In December 2025, Railroading Heritage of Midwest America (RRHMA) completed restoration work on the headlight and number plate of Union Pacific No. 5511 at its Silvis, Illinois facility. The locomotive’s number plate, a single-piece cast steel component mounted directly to the smokebox, was refinished and restored to original factory appearance. The number plate also functions as the mounting bracket for the Pyle-National headlight, consistent with original Union Pacific design. The headlight assembly underwent complete disassembly and rewiring, with the installation of new internal wiring, fixtures, and electrical components. Period-correct replacement lenses and reflectors were installed to restore proper illumination and appearance. The side-mounted numberboard indicators were cleaned, refurbished, and retained for reuse. This work returned the headlight and number plate to original operational and visual specifications as part of the broader restoration of No. 5511.[15]
UP 5511
Trivia[]
- During its storage at Cheyenne after retirement, the crosshead’s connection to the cylinder was cut for ease of movement. Despite this, it is in okay mechanical condition.
- 5511 was shown briefly in UP's Last Of The Giants; to give the illusion that it was operational, burning tires were put in its firebox and the train was pushed from the rear by a diesel locomotive. Because of this the deposits will have to be chiseled out before work on the engine can begin.
- 5511 is the only surviving member of its class in preservation and is also the only mechanically complete steam locomotive in the U.S. equipped with Young valve gear.