Pennsylvania Railroad 5550, named Dave Fink, is a mainline duplex drive steam locomotive under construction in the United States. With an estimated completion by 2030, the locomotive will become the 53rd example of the Pennsylvania Railroad's T1 steam locomotive class and the only operational locomotive of its type, as well as the largest steam locomotive built in the United States since 1952 and the only existant duplex locomotive in the world. The estimated cost of PRR 5550 Dave Fink was originally $10 million, but an updated projected cost of $7 million was released with the acquisition of an existing long-haul tender from the Western New York Railway Historical Society in August 2017. Construction began in 2014 with the casting of the locomotive's keystone-shaped number plate. As of May 2026 the locomotive is 65.4% complete. The T1 Trust, the nonprofit constructing the locomotive, has so far completed all 8 driving wheels as well as the boiler, cab, keystone, frame and the cylinders.
Introduction The original T1 class
The Pennsylvania Railroad class T1 class steam locomotive was a unique and controversial class of locomotives. This was due to its unusual duplex drive 4-4-4-4 wheel arrangement, its use of the Franklin Type A oscillating-cam poppet valve, and its characteristic streamlining conceived by renowned industrial designer Raymond Loewy. The T1 was also the only class of Pennsylvania duplex able to travel the railroad's entire network and the first production series locomotive designed to use the poppet valve. The two prototype T1 locomotives were constructed in 1942 by the Baldwin Locomotive Works, numbered 6110 and 6111 respectively. Of the fifty production units, twenty-five (numbered 5500 to 5524) were constructed at the Pennsylvania Railroad's Altoona Works and twenty-five (numbered 5525 to 5549) at Baldwin, for a total of fifty-two T1 class locomotives. This made the T1 the most-produced of all the Pennsylvania Railroad's duplex-drive locomotives.
The T1 class suffered from several performance and design issues, including difficulties with the poppet valves. The original materials used to construct the valves were subject to fatigue issues, particularly when the locomotives were operated above 100 miles an hour. When Franklin received complaints about this, they sent some of their employees on trains hauled by the T1. They timed the train between stations. The engineers apparently reported the T1 operating at speeds above 130 miles per hour. These speed timings resurfaced through interviews decades later. In 1947, a higher-strength and fatigue-resistant alloy was used and retrofitted to the T1 class to solve the fatigue problems. Nevertheless, the design of the Franklin Type A poppet valves made several key areas of the valves hard to access during maintenance overhauls. Despite these issues, the poppet valves did improve the T1's high-speed performance, requiring less horsepower and distributing steam flow with greater precision. The T1 locomotives were further burdened by excessive wheel slip on one of the two engine sets at startup or high speed. The Pennsylvania Railroad tried to address the problem by changing the spring bed arrangement on the T1—from a single bed, supporting all eight drivers, to two beds, each of which supported one of the engines and its adjacent truck. However, no complete solution was found to the problem of wheel slip, even though an "anti-slip" mechanism had been previously installed on the PRR Q2-class duplex. One possible reason is that the engineers, familiar with the slower throttle action of the K4 class, were unprepared for the T1's more immediate throttle response.
Before many of the problems that plagued the T1 class could be solved, the Pennsylvania Railroad decided to begin the transition from steam power to diesel. Moreover, these problems ensured that the T1 class would be retired before more reliable steam engine classes such as the K4s. The T1 locomotives were retired between 1952 and 1953. Scrapping began in 1953, and the last surviving T1 was scrapped in 1956. The hasty retirement of the T1 left several performance-related and technical questions unanswered.
The T1 Trust The Pennsylvania Railroad T1 Steam Locomotive Trust, also referred to as the T1 Trust, is a non-profit public charity founded in 2013. The T1 Trust is composed of railroading experts who intend to build the 53rd member of the T1 class and put it into mainline steam excursion service within the United States. The last production T1 bore the number 5549, making 5550 the logical choice for the new locomotive's number. The T1 Trust's goal was to construct the locomotive within 17 years (by 2030) at an estimated cost of $10 million. The price is based on calculated costs for inflation, labor, material, fabrication, retooling, and design. Lessons learned during Tornado's construction in the U.K. were also taken into account. The T1 Trust chose to build a T1, rather than a proven design such as the New York Central Railroad's "J" class Hudsons, to test the T1 class's long-rumored performance and to avoid conflicts of interest with other locomotive replication projects.
World Steam Speed Record The builders of PRR 5550 hope to break the world steam speed record, which is held by the LNER Class A4 4468 Mallard at . The 5550 will operate under its original design with no major modifications in its attempt to break the record. It has been claimed that PRR T1 locomotives were capable of achieving speeds in excess of with lighter trains of six or seven cars, and the T1 Trust believes the original T1 design is capable of achieving this feat.
Design and construction Project leadership, techniques, and organization The chairman of the T1 Trust is Bradford Noble, with Scott McGill the chief mechanical officer, Wes Camp the director of operations, and Jason Johnson the general manager. The project structure is similar to that used by the A1 Trust to accomplish the funding and construction of Tornado. To do this, the T1 Trust reached out to the UK-based A1 Trust and its engineering director, David Elliot, who gave important advice on organizational structure and engineering techniques to be used when critical information or blueprints regarding specific locomotive parts or needed materials are absent. Other UK-based organizations that are helping or working with the T1 Trust include the BR Class 8 Steam Locomotive Trust, the Caprotti Black 5 Limited and the P2 Steam Locomotive Company. The T1 Trust has sponsorship programs, where donors can choose to sponsor driving wheels or other parts of the locomotive as well as sponsoring blueprints. This along with occasional Kickstarter campaigns, regular monthly donations, one-time donations and membership for the Trust's "Founders Club" help raise the money necessary to construct the locomotive. The CMO of the Trust, Scott McGill, visited the Pennsylvania State Archives in Harrisburg, Pennsylvania, where he scanned hundreds of original drawings and blueprints of the Pennsylvania Railroad class T1 from the Pennsylvania Railroad collection into digital formats.
By November 2016, most of the scanning work had been completed with 1,638 of the 1,798 needed drawings and blueprints having been scanned and acquired by the T1 Trust. Only 150 of the drawings are missing from the collection, and these are composed mainly of simple fasteners and other readily-available, commercial components. The digitally-scanned drawings collected by the T1 Trust are used to create detailed and intricate 3D Models using the Dassault Systèmes SolidWorks computer aided drafting (CAD) program. For construction of the locomotive's many pieces and components, the T1 Trust contracts with different manufacturers and organizations such as the Strasburg Rail Road and Diversified Rail Services. The T1 Trust also prints a quarterly newsletter called the T1 Trail Blazer, which is received by members of the Trust's "Keystone Society": a group of donors that either pledge life income gifts to the Trust or pledge to list the Trust as an estate beneficiary. In September 2016, Doyle McCormack, a locomotive engineer best known for restoring and operating the GS-4 class 4-8-4 steam locomotive Southern Pacific 4449, joined the T1 Trust as a member of the organization's advisory board.
First signs of progress Construction of PRR 5550 was officially started on May 31, 2014, with the completion of the locomotive's bronze keystone-shaped number plate, following a successful conclusion to the initial Kickstarter campaign launched by the Trust. The number plate was cast by traditional methods by a member of the T1 Trust, Chuck Blardone, at an Amish foundry within Lancaster County, Pennsylvania. This was followed by the construction of the first driving link pin, in October 2014. On May 2, 2014, the T1 Trust began meetings and discussions with the Federal Railroad Administration (FRA) to help ensure that PRR 5550 is constructed to FRA standards. The T1 Trust's application to the Internal Revenue Service (IRS) to operate as a federally approved tax-exempt 501(3)(c) charity was approved in July 2014. By March 2015, Steamtown National Historic Site, the Steam Railroading Institute (SRI) and the Cuyahoga Valley Scenic Railroad (CVSR) expressed interest to the T1 Trust to have the locomotive run on their premises. A part sponsor named Gary Bensman constructed the headlight of PRR 5550 in May 2015 and donated it to the T1 Trust. As a sign of gratitude, Bensman's name was engraved into the headlight by the Trust.
Wheelset and engine assembly
5550 is slated to use the Franklin Type B2 rotary-cam poppet valves in place of the Type A oscillating-cam poppets due to an increased ease of maintenance and superior performance. Although an unusual arrangement, it is not the first time the Type B poppets were used on a Pennsylvania Railroad class T1. In 1948, T1 number 5500 was rebuilt to use the Type B2 poppets following a damaging collision with a K4s in St. Louis, Missouri. Franklin Type B gear was applied to a handful of locomotives starting in 1948, including K4s 3847, which had been designed or built with conventional piston valves. Type B2 was devised specifically for the T1 as the existing valve arrangement from the Type A gear differed from Type B. 5500, perhaps the first locomotive fitted with two types of poppet valve gear, was soon noted for its superior performance over the other engines of its class. The Pennsylvania Railroad at one point even considered retrofitting the Type B2 poppets to other T1's, but this action was never taken. The Pennsylvania Railroad also experimented with the idea of fitting the T1 with conventional Walschaerts valve gear and retrofitted number 5547 to such a configuration.