The number 7 and number 8 Boxpok driving wheels cast for PRR 5550, the first of their kind to be cast in the United States since the late 1940's.

By Source (WP:NFCC#4), Fair use, https://en.wikipedia.org/w/index.php?curid=54047415

PRR 6110, the prototype for the T1 class steam locomotive built for the Pennsylvania Railroad by the Baldwin Locomotive Works seen in 1942.

The prow of PRR 5550, as completed in May 2017, featuring the keystone number plate and headlight.

By Source (WP:NFCC#4), Fair use, https://en.wikipedia.org/w/index.php?curid=54073491​

The number 7 and number 8 Boxpok driving wheels cast for PRR 5550, the first of their kind to be cast in the United States since the late 1940s.
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Artist's rendition of PRR 5550 when finished.

By Source (WP:NFCC#4), Fair use, https://en.wikipedia.org/w/index.php?curid=54051686

The prow of PRR 5550, as completed in May 2017, featuring the keystone number plate and headlight.

PRR 5549, a production series T1. 5549 was the last of the 27 T1s constructed by Baldwin.

USATC 611, a USATC S160 Class steam locomotive.

PRR 6110, the prototype for the T1 class steam locomotive built for the Pennsylvania Railroad by the Baldwin Locomotive Works seen in 1942.

PRR 5549, a production series T1. 5549 was the last of the 27 T1s constructed by Baldwin.

USATC 611, a USATC S160 Class steam locomotive, is currently the only surviving engine to be fitted with the Franklin Type B Rotary Cam poppet valve, intended for use on PRR 5550. Note the large eccentric gear above the first two driving wheel sets, iconic to the Type B valve. By Source (WP:NFCC#4), Fair use, https://en.wikipedia.org/w/index.php?curid=54047597

PRR 5550 Streamlined 4-4-4-4 Duplex Drive Steam Locomotive
Pennsylvania Railroad 5550 is a mainline duplex drive steam locomotive currently under construction in the United States of America. Upon completion, estimated to be around 2030, the locomotive will be the 53rd addition to (and only extant example of) the Pennsylvania Railroad's T1 steam locomotive class. The total estimated cost of PRR 5550 was US $10,000,000, but with the acquisition of an existing long haul tender from the Western New York Railway Historical Society in August 2017, the total cost is now estimated to be closer to US $7,000,000. The project is following some of the protocols and objectives laid down during the construction of the LNER Peppercorn Class A1 steam locomotive Tornado in the United Kingdom. The T1 Trust has also worked closely with many United Kingdom based steam locomotive foundations to aid in the construction of PRR 5550. Construction of the locomotive began in 2014 with the casting of the locomotive's keystone-shaped number plate; several other key pieces, such as the cab, two of the Boxpok driving wheels, and parts of the boiler, were complete as of August 2018.

Introduction
The Original T1 Class
The Pennsylvania Railroad's T1 class steam locomotive was one of the most unique and controversial class of locomotives ever constructed. 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 famous industrial designer Raymond Loewy. The T1 was also the only class of Pennsylvania duplex able to travel on all of the railroad's network. The T1 was also 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 production series for the T1 class, with 25 locomotives Numbered 5500 to 5524 being constructed at the Pennsylvania Railroad's Altoona Works and the other 25 locomotives Numbered 5525 to 5549 being constructed at Baldwin. In total, 52 T1 class locomotives were constructed including the two prototypes.This made the T1 the most numerous engine produced of all the Pennsylvania Railroad's duplex drive locomotives.

The T1 class suffered from a number of performance and design issues including difficulties regarding the poppet valves used by the locomotives. The original materials used to construct the poppet valves used by the T1 had fatigue issues which were increased when the locomotives were operated above 100 miles an hour. 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 the constant issues, the poppet valves did allow the T1 to perform better than conventional valved locomotives at high speeds. The poppet valves required less horsepower for fast operation and were able to distribute steam flow with precision valve operation when running at high speeds. The T1's were further burdened by excessive wheel slip on one of the two engine sets when the locomotive operated at high speed or when the engine started moving. The Pennsylvania Railroad tried to address the problem by changing the spring bed arrangement on the T1, from being a single bed that supported only the eight drivers, to two beds; the forward bed supporting the pilot truck and first engine and the aft bed supporting the second engine and trailing truck. Despite this, a permanent solution couldn't be found to ultimately prevent violent wheel slip, even though an "anti-slip" mechanism had been installed on the PRR Q2 class duplex. It is possible that the engineers, more familiar with the K4s class were better used to the slower throttle action of the K4s, whereas the T1 reacted more immediately to the engineer's throttle input due in part to the use of poppet valves.

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. Furthermore, the problems associated with the operation of the T1 locomotives would help to ensure an earlier retirement from service as compared to the more reliable steam engine classes such as the K4s. Between 1952 and 1953, the T1's were retired from service within the Pennsylvania Railroad. Scrapping of the T1's began in 1953. The last surviving T1's were scrapped in 1956. Consequently, the premature retirement and disposal of the T1 left several vague speed claims and performance related or 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 several railroading experts which include professional engineers, historians and steam locomotive operators. The T1 Trust is building the 53rd member of the long extinct Pennsylvania Railroad class T1 class locomotive, numbered 5550, meant for mainline steam excursions within the United States and to provide an example of a missing link in American railroading history. The number of 5550 was decided either by the last production T1 bearing the number 5549, or that the sum of the numbers of the currently preserved streamlined steam locomotives in the United States equaling 5550 (SP 4449 + N&W 611 + C&O 490 = 5550). An immediate goal was set by the T1 Trust to construct the locomotive within a 17-year span, hopefully allowing PRR 5550 to be completed by 2030 at an outstanding cost of $10,000,000 US. The price was based off calculations regarding several factors, which included inflation, labor costs, material costs, fabrication costs, retooling costs and design costs. The calculations were also based off similar examples taken under consideration during Tornado's construction in the U.K. An operational example of a T1 could answer unproven claims or otherwise unanswerable questions about the operational capabilities of the T1. This is a major reason why the T1 Trust has decided to construct a T1 rather than a proven design such as the New York Central Railroad's "J" class Hudsons, which famous for pulling the 20th Century Limited. Another reason was to avoid a conflict of interest with other projects that are currently trying to replicate the Hudsons or other lost classes of American engines.

World Steam Speed Record
A major role the T1 Trust intends for PRR 5550 to fill is to break the current world steam speed record, which is currently held by the LNER Class A4 4468 Mallard at 125.88 miles per hour (203 km/h). The T1 Trust believes the reputation of the T1 could be changed if the record was taken by 5550. Another reason the T1 Trust intends to break the record is to try and raise nationwide support for the project. The Trust speculates most American railroad enthusiasts tend to be centered towards their favorite railroad, therefore enthusiasts not centered around the Pennsylvania Railroad would be less likely to support the construction of PRR 5550 if not for the speed record attempt. However, no major design changes will be made to 5550 for the record attempt. The T1 Trust believes the original T1s, as built, were very capable of exceeding 120 miles an hour in service, which would increase the likelihood of a T1 breaking Mallard's speed record. There are also claims stating the original T1s operated at higher operational speeds than the official recorded speed held by Mallard. It has been reported that PRR T1 locomotives were capable of achieving speeds in excess of 140 miles per hour with fully loaded trains. These performance capabilities are one of the reasons the T1 Trust believes the T1 class to be the pinnacle of American steam engine development and construction.

Design and Construction
Project leadership, techniques and organization
The chairman of the T1 Trust is Bradford Noble, with Scott McGill being the Chief Mechanical Officer, Wes Camp being the Director of Operations and Jason Johnson the General Manager. The project structure is in a similar fashion 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 United Kingdom 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 United Kingdom 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 to different manufacturers and organizations such as the Strasburg Rail Road or 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 investors 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 best for restoring and operating the 4-8-4 GS-4 class 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 forged by traditional methods by a member of the T1 Trust, Chuck Blardone, at an Amish forge 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 to help ensure that PRR 5550 is constructed to FRA standards. The T1 Trust's application to the United States 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 and the Cuyahoga Valley Scenic Railroad 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 B poppets following a damaging collision with a K4s in St. Louis, Missouri. 5500 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 B poppets to other T1's, but this action was never taken. It is worth noting the Pennsylvania Railroad also experimented with the idea of fitting the conventional Walschaerts valve gear to the T1 and retrofitted number 5547 to such a configuration. To aid in the reconstruction of the Type B2 poppets, the T1 Trust was generously given full access to the USATC S160 Class 2-8-0 USATC No. 611 by Bill Miller Equipment Sales. USATC 611 is located along with its owner in Eckhart Mines, Maryland. USATC 611 was fitted with Franklin Type B1 rotary-cam poppet valves during the 1950s during its career at Fort Eustis, Virginia. The T1 Trust hopes to do a full inspection and documentation of key features within the Type B1 poppets to use as a basis for reconstructing the Type B2 poppets proposed for use on 5550. It is also hoped that the investigative work and documentation can aid a future restoration of USATC 611. The P2 Steam Locomotive Company is also planning on using the Franklin Type B Rotary Cam poppet valve (albeit the earlier B1 model) for the proposed new build LNER Class P2 steam locomotive, No. 2007 Prince of Wales, and has shared valuable design documents to the T1 Trust needed to reproduce the valve. Components of the Caprotti valve gear will be examined to help recreate the gear box of the Type B2 poppet valve as the original blueprints of the Type B2 gearbox have been lost. The copies of design documents and blueprints of the Caprotti gearbox were provided by the BR Class 8 Steam Locomotive Trust and Caprotti Black 5 Limited.

The eight Boxpok driving wheels of the original T1's were 80 inches (2,032 mm) in diameter and were of a hollow steel design where as a conventional steam locomotive driving wheel is completely solid. The design is also a higher strength than conventional driving wheels and ideal for high speed operations. On July 8, 2015, the T1 Trust launched a Kickstarter campaign titled "Let's Get Rolling" to raise $20,000 to be used in the design and building of a casting pattern for the new Boxpok drivers. The campaign reached over its goal and construction began on the casting patterns, which were finished in October 2015. Construction of the casting patterns was undertaken by Liberty Pattern in Youngstown, Ohio using a complex CAD model made of PRR 5550's proposed number four wheelset. Casting of the drivers was awarded to Beaver Valley Alloy in Monaca, Pennsylvania. On February 26, 2016, Beaver Valley Alloy cast the first of eight driving wheels at its foundry successfully. This historic event marked the first time a steam locomotive driving wheel had been cast in the United States since the 1940s. A second driver was ordered on December 9, 2016 and was cast by Beaver Valley Alloy on March 6, 2017. The second Boxpok was delivered to the T1 Trust on March 15, 2017 and placed next to the first completed driver. Both drivers represent the number four wheelset. Two more Boxpok drivers and the connecting rods are anticipated to be completed by the end of 2017.

Aluminum components
The cab of the locomotive is of aluminum construction. This is not a new feature as the cabs of the previous T1's were also made of aluminum, which was done to reduce weight. The streamlining of the locomotive, like the cab, also consists of aluminum construction. Digitization of the original cab blueprints was undertaken by JAKTOOL in Cranbury, New Jersey. On January 18, 2017, the frames and main components of the cab were cut by Gemini Industrial Machine in Dover, Ohio, beginning construction of the cab. Construction of the cab was contracted to Curry Rail Services in Hollidaysburg, Pennsylvania. By coincidence, the facility currently housing Curry Rail Services was previously the Pennsylvania Railroad's Samuel Rea Car Shops. The cab was completed on July 10, 2017, albeit unpainted.

Construction on the "prow" portion of the locomotive's streamlining, also made of aluminum, began on November 10, 2016 by Gemini Industrial Machine. This part of the structure houses the headlight and keystone number plate. Using existing CAD models, a water jet cutter, bodywork, fabrication and paint, the prow was completed on May 16, 2017 with the headlight and keystone number plate attached.

Locomotive frame
As of Fall 2017, the frame of PRR 5550 is currently being transferred from original Pennsylvania Railroad blueprints to CAD software by JAKTOOL. The model is reported to be around 30 percent complete, with all work hours being donated. Both the left and right sides of the frame structure are expected to be symmetrical.

Boiler
On January 26, 2018, the T1 Trust announced it had ordered the first and second courses of the massive boiler. The courses are the largest parts of PRR 5550 ordered to date. The first two sections of the boiler will be constructed from 1 inch (25 mm) thick boiler code steel and will each be 93 inches (2.4 m) in diameter and 12 feet (3.7 m) in length. The sections will be welded and will include openings for water refilling along with washout plugs. Once finished, the welds made will be x-rayed to detect and prevent any possible defects or flaws. The order was placed with Continental Fabricators in St. Louis, Missouri, which as of February 2018 is involved in at least 3 other steam engine boiler construction projects and has been involved in steam locomotive projects since the 1980s.

The design of 5550's boiler is being handled by the T1 Trust's boiler engineering team, lead by Wolf Fengler. Others working on the design of the boiler include Trust members Gary Bensman, Dave Griner, Scott McGill and Jason Johnson. The team is re-engineering the T1 boiler and firebox design to exceed current ASME standards and codes.

Tender
On August 7, 2017, the T1 Trust purchased the sole surviving "Coast to Coast" 16 wheeled tender from the Western New York Railway Historical Society for eventual use on PRR 5550. According to the Trust, the purchase of said tender reduces the overall cost of the project by at least $3,000,000 US. The tender, No. 6659, is a class 210-F-75A originally built for an M1 class 4-8-2 Mountain type. At some point in its existence, the mechanical stoker and "doghouse" structure were removed when the Pennsylvania Railroad converted it into a mobile water tank. Prior to the sale, the Historical Society planned to display the tender behind PRR 4483, an I1sa class 2-10-0 locomotive. Currently, the tender sits North Collins, New York. The Trust agreed to help restore the tender currently paired with the Historical Society's I1sa as part of the M1 tender purchase agreement. The Trust plans to perform a mandatory test of the tender's brake system, restore the brake systems, replace the oil in the roller bearings and move the tender to Hamburg, New York for repainting and final restoration. To help fund the tender restoration, the Trust has created a separate donation fund for this task and will display the names of all donors who pledge $500 or higher to the fund on a bronze plaque placed upon the tender itself. Total cost of the tender restoration is estimated to be more than $50,000. On October 5, 2017, an automatic coal stoker was donated to the Trust. The motor, coal crusher, gearbox, stoker trough and reversing valve were donated by Gary Bensman and Warren Lathom.

Project milestones
2013: The Pennsylvania Railroad T1 Steam Locomotive Trust is founded.
2013: The T1 Trust begins scanning original blueprints and documents of the Pennsylvania Railroad at the Pennsylvania State Archives.
2014: The keystone shaped number plate is cast starting the construction of PRR 5550, April 3, 2014.
2014: 501(c)(3) status is granted to the T1 Trust by the IRS, July 3, 2014.
2014: Work starts on the Boxpok driver center casting patterns, December 14, 2014.
2015: The headlight for PRR 5550 is constructed and donated by parts donor Gary Bensman.
2015: "Let's Get Rolling" Kickstarter campaign launched to fund the casting of the first Boxpok driver, July 8, 2015.
2015: "Let's Get Rolling" Kickstarter campaign completed raising $2,577 over the intended $20,000 goal, August 7, 2015.
2015: Boxpok driver center casting patterns completed, October 22, 2015.
2016: First Boxpok driver is cast, February 26, 2016.
2016: Doyle McCormack joins the T1 Trust, September 9, 2016.
2016: Construction of the locomotive prow begins.
2016: Scanning of PRR original blueprints and documents nears completion, November 2016.
2016: Second Boxpok driver is ordered, December 9, 2016.
2017: Construction of the locomotive cab begins, January 18, 2017.
2017: Second Boxpok driver is cast, March 6, 2017.
2017: Prow completed with headlight and number plate installed, May 16, 2017.
2017: Cab completed but left unpainted, July 10, 2017.
2017: Tender purchased from Western New York Railway Heritage Society, August 7, 2017.
2017: PRR 5550 is estimated to be 28.1 percent complete, August 7, 2017.
2017: All necessary parts for an automatic coal stoker are donated to the Trust, October 5, 2017.
2018: First section of the boiler is ordered, January 26, 2018.
2018: Second section of the boiler is ordered, January 28, 2018.
2018: $5,000 USD Grant awarded to the T1 Trust by the Tom E. Daily Foundation for Tender brake work, February 3, 2018.
2018: Third section of the boiler is ordered, May 4th, 2018.

2018: First and second boiler sections are completed and welded together, March 6, 2018.
2018: Third section of the boiler is ordered, May 4, 2018.
2018: The third boiler section is completed and welded into place, June 15, 2018.

Pennsylvania Railroad 5550 Overview
Type and origin
Power type: Steam
Builder: Pennsylvania Railroad T1 Steam Locomotive Trust
Build date: 2014–Appx. 2030
Specifications
Configuration:
​ • Whyte 4-4-4-4
Gauge: 4 ft 8 1⁄2 in (1,435 mm)
Driver diameter: 80 in (203 cm)
Wheelbase: 107 ft (33 m)
 • Engine: 51.92 ft (16 m)
 • Drivers: 25.33 ft (8 m)
 • Tender: 52 ft (16 m)
Length: 122 ft 9 3⁄4 in (37 m)
Width: 10 ft 0 in (3 m)
Height: 15 ft 10 in (5 m)
Frame type: Rigid
Adhesive weight: 279,910 lb (126,965 kg)
Locomotive weight: 502,200 lb (227,794 kg)
Tender weight: 197,500 lb (89,584 kg)
Total weight: 699,700 lb (317,379 kg)
Tender type: Class 210-F-75A Tender
Fuel type: Coal
Fuel capacity: 62,000 lb (28,123 kg)
Water capacity 18,000 US gal (68,137 L)
Firebox:
 • Firegrate area: 92 sq ft (9 m2)
Boiler:
​ • Diameter: 91 1⁄2 in (2 m)
 • Tube plates: 214 13⁄16 in (5 m)
Boiler pressure: 300 psi (2,068 kPa)
Heating surface: 5,639 sq ft (523.9 m2)
 • Firebox: 490 sq ft (46 m2)
Superheater:
​ • Heating area 1,430 sq ft (133 m2)
Cylinders: Four
Cylinder size: 19.75 in × 26 in (502 mm × 660 mm)
Valve gear: Franklin Type B2 rotary-cam
Valve type: Poppet
Performance figures
Maximum speed: estimated to be more than 126 mph (203 km/h)
Career
Operator: Pennsylvania Railroad T1 Steam Locomotive Trust
Class: Pennsylvania Railroad T1
Number in class: 53 (52 built in the 20th Century, and 1 under construction)
Road Number: 5550
Disposition: Currently under construction.

See also:

The T-1 Trust Official Website: https://prrt1steamlocomotivetrust.org/

Duplex locomotive

PRR T1

Pennsylvania Railroad

Streamlined Steam Locomotives

Steam Locomotives

Locomotives

Artist's rendition of PRR 5550 when finished.