The wheel slip issue had two root causes. The first was ineffective spring equalization. As originally designed (engines 6110 and 6111), the engine truck was not equalized with the drivers, and all four pairs of drivers were equalized together. When entering curves or moving over track that was less than perfectly level, weight was transferred off the front engine, causing the front pairs of drivers to slip. This condition was observed at all speeds, and we believe is the basis for the “uncontrollable” reputation the T1 has. The PRR addressed this in the production fleet by splitting the spring rigging in two – the front engine was equalized with the engine truck, and the rear engine was equalized with the trailing truck. The other root cause was improper handling. Engineers assigned to T1s were given no formal training on how to operate them, and their performance was very different than the K4’s most of them were accustomed to. The front end throttle, high boiler pressure, very large diameter steam delivery pipes, and poppet valves combined to make the T1’s very responsive to throttle application compared to a K4. Too much power applied too quickly resulted in wheel slip, especially at speeds around 15-25 mph. We will be performing kinematic and compliance simulations of the spring rigging and equalization to determine whether further improvements in adhesion are possible. We will be applying a wheel slip alarm, so the engineer would be made aware of a wheel slip more quickly should it occur, and reduce power manually. We will also investigate fitting an electro-mechanical anti-slip device similar in concept to that fitted to the Q2, but with more reliable valves and modern electronics, so no involvement from the engineer would be required.
From what we’ve seen, the PRR solved this problem by 1947, by changing the valves from mild steel to a higher strength alloy that was better able to cope with the fatigue issues at service speeds. We will run durability and fatigue simulations for speeds in excess of the T1’s rumored top speed, and select alloys and manufacturing processes to maximize reliability.
We haven’t researched the full service career of the T1 fleet, so we can’t say for certain how often it happened, but the answer is definitely yes. 25 of them were built at the Baldwin Locomotive works in Eddystone, PA, just south of Philadelphia, and there are references to one being displayed at railroad equipment shows in Reading PA, and Asbury Park, New Jersey. T1 #5542 was assigned to pulling train No. 17 between Broad Street Philadelphia and Pittsburgh station at least once. However, there was little need for the T1 to run east of Harrisburg, as that region was electrified, and blue ribbon trains were serviced by the GG1.
Presently there are only two possibilities, neither of which is likely for revenue service – The USDOT test loop in Pueblo, and portions of the Northeast corridor. The DOT facility is where we would intend to perform high speed testing to confirm the locomotive’s tracking qualities and top speed potential, with an instrumented test train, and only in compliance with all applicable DOT regulations. High speed running is not necessarily part of the routine service plan. Our intent is to maintain schedule on whatever railroad is willing to host the locomotive for excursion service. We anticipate this will be limited to 79mph top speeds on one or more of the Class 1 railroads. If, however, Amtrak can be persuaded to allow excursion trains on their system, we would plan on operating at speeds of 85-110 mph plus to match their timetable.
A more relevant question would be “where could it run?” The answer to that is – just about anywhere. Unlike the S1, the T1 was designed to operate anywhere on the PRR mainline circa 1942. With the original lateral motion configuration, the T1 could negotiate 16 degree curves, and according to the timetable, could operate in areas where even the M1 was restricted. A specific problem with 130 lb no.8 switches prevented them operating through Pittsburgh – but an increase in lateral motion in 1946, and track realignments in the modern era (required to handle longer freight cars than the 1940’s) mean that this particular issue has been resolved. Based on the revised lateral motion, and the overall dimensions, we’re confident that the T1 can operate anywhere on the current mainline network that the N&W J class can. As part of our project, we will investigate a further increase in lateral motion to allow negotiation of 20 degree curves, which would let the T1 operate on any track currently accessible to a NKP Berkshire.
At this point in time, the Trust does not have an agreement in place to operate the locomotive on any class 1 railroad. We will attempt to secure support from a Class 1 carrier once the project is further along.
The T1 Trust has received letters of intent from three well established tourist railroads; the Steamtown National Historic Site in Scranton, PA, the Steam Railroading Institute in Owosso, MI and the Cuyahoga Valley Scenic Railroad in Independence, OH. All three of these fine organizations are experienced in handling mainline steam locomotives and can easily support the operation of the T1 locomotive when complete.
Our current estimated completion date is 2030. This was based on our own internal estimates of the number of man hours required to complete certain tasks, as well as the duration of the A1 “Tornado” project in the UK. In reality, the program timing will likely be dependent on manpower and funding. If we don’t get the volunteers needed to complete the engineering and construction, or the funds to produce the parts, it could take much longer. Conversely – if we received a donation of $20 Million tomorrow, we could hire a full time professional engineering and fabrication staff, and the project could be completed in as little as 5-6 years.
The research alone involved in this project is no small task. We’ve read most of the published literature on the T1 to get a feel for the real problems that existed with the design, and develop plans to address them. T1 Trust volunteers have gathered over 1,000 original engineering drawings and test reports for the T1 from the PRR and Baldwin Locomotive Works collections. The archival blueprints have been used to generate 3D CAD models for many of the parts in Solidworks, and we’ve contacted suppliers for tooling and component manufacturing. The massive and complex wooden patterns for the T1’s driving wheels were constructed at Liberty Pattern in Youngstown, Ohio and on February 26, 2016 the first driving wheel was cast at Beaver Valley Alloy in Monaca, Pennsylvania.
The T1 Trust’s engineers have developed plans for an all welded boiler, and as the CAD modeling effort continues, more attention will be focused on the design of a revised locomotive frame. Ultimately the design will be subjected to multi physics testing to ensure optimal performance. In addition, The T1 Trust plans to produce a few more “showpiece” parts for public display, to raise awareness and to encourage donations.
There are a number of railroad contractors who can fabricate the components necessary to build the locomotive. These include Diversified Rail Services, Steam Operations Corporation, Steam Services of America, and the Strasburg Rail Road. The T1 Trust has already worked with the Strasburg Rail Road on engineering for the T1 and in tapping the threads for the 5550 Keystone. Diversified Rail Services has completed construction of the headlight for 5550 and is currently making the prow hinge. The T1 Trust is looking forward to doing business with a multitude of qualified vendors in realizing the completion of T1 number 5550.
Generally speaking, the answer to this question is “no” – or at least, not to any significant extent. The principal reason for this is that the T1 needs all of the weight it was originally designed with for rail adhesion. The T1 had a designed factor of adhesion over 4.1, which is generally considered ideal for a steam locomotive. Even though it would be possible to reduce weight by going with higher strength alloys in some applications, taking weight out would reduce the factor of adhesion, resulting in an increased propensity for wheel slip. Given the T1’s reputation, it would not be advisable to reduce factor of adhesion significantly. To counteract a sizeable weight reduction and maintain factor of adhesion, we’d need to significantly reduce the power that the locomotive was capable of, which would severely limit the locomotive’s high speed potential. We do not need to reduce weight to satisfy modern axle loading limits, so there’s little to be gained by a weight reduction program.
Another reason not to go for lightweight alloys is stiffness. Even though there is a lot of variation in strength to weight ratio among various alloys, there is almost no difference in stiffness to weight ratio. A thinner, lighter alloy will reduce stiffness, which may result in unforeseen failure modes not present in the original design due to the increased flexion.
As it is, we may need to add ballast to counteract weight loss resulting from manufacturing decisions. For example, we intend to build a fully welded boiler instead of the riveted design originally used. Even though we will be maintaining the overall size, thickness, and alloys used originally (to maintain structural stiffness of the boiler), the loss of the overlapping seams of the riveted design will result in weight loss. This will probably be in excess of any weight increase resulting from the thicker firebox needed to maintain the current federally mandated safety factor of 4.0 on boilers. (PRR Belpaire boilers were designed to a lower safety factor acceptable at that time.) Additionally, we also intend to use the Franklin Type B2 rotary cam valve gear, instead of the Type A oscillating cam gear that the T1 originally used. Our decision to use rotary cam valve gear is driven by ease of maintenance and reduced fabrication costs compared to the oscillating cam gear, but the rotary cam gear weighs about three tons less, so we may need to ballast the locomotive to maintain weight distribution.
The only area that we may elect to substitute a different material is the poppet valves. The originals were made of a high alloy steel that had some issues with durability. To improve reliability, we may investigate an alternate high strength material such as titanium. This might reduce the valve weight from approximately 4 pounds to as little as 2.5 pounds. Not a significant savings in the big picture (50 pounds total), but lighter valves will reduce reciprocating mass, which will allow for softer return springs. This will reduce the closing force on the valve seats while keeping valve float in check, which should improve reliability beyond any improvements based on alloy strength alone.
Despite its age, the T1 used a lot of very high strength and light weight alloys in its construction. The cab, boiler jacket, and streamlining were made of 6000 series aluminum, which saved about 16,000 pounds compared to a steel skin. Siderods, piston rods, crossheads, and crankpins are made from Timken high dynamic steel, which has a yield strength of 110,000 psi, and a high elongation. Spacecraft grade 7000 series aluminum was used for the crosshead shoes. Nearly all the large castings used General Steel Castings’ Nickel Steel. This nickel steel alloy had a much higher elongation than is typical in commercially available steel alloys today. Fortunately with the help of Beaver Valley Alloy and a national materials testing laboratory, The T1 Trust has been able to utilize 21st Century technology to successfully replicate General Steel Castings’ Nickel Steel.
At this point – no, there are no plans to equip 5550 with ditch lights. FRA regulations for steam locomotives have no specific requirement for ditch lights:
§ 230.86 Required illumination.
Basic Version
a) General provisions. Each steam locomotive used between sunset and sunrise shall be equipped with an operable headlight that provides illumination sufficient for a steam locomotive engineer in the cab to see, in a clear atmosphere, a dark object as large as a man of average size standing at least 800 feet ahead and in front of such headlight. If a steam locomotive is regularly required to run backward for any portion of its trip other than to pick up a detached portion of its train or to make terminal movements, it shall also be equipped on its rear end with an operable headlight that is capable of providing the illumination described in this paragraph (a).
b) Dimming device. Such headlights shall be provided with a device whereby the light from same may be diminished in yards and at stations or when meeting trains.
c) Where multiple locomotives utilized. When two or more locomotives are used in the same train, the leading locomotive only will be required to display a headlight.
But since we’re new construction replicating a historic piece, not an *actual* historic piece, we may be in a grey area. From our initial conversations with the FRA, we got the impression that they don’t differentiate between old and new steam locomotives. However, we’ll need to confirm this with both the FRA and host railroad before the locomotive enters service.
