This year sees the 25th anniversary of the launch of the A1 Steam Locomotive Trust, a Darlington-based charity formed for the purpose of building steam locomotives from scratch for use on main lines and preserved railways. The trust began building the No 60163 Tornado A1 steam locomotive to the original design in 1990. After 18 years of planning, construction and fundraising, the £3 million loco was completed in 2008.
Now, to mark its anniversary, the trust has decided to begin building the seventh Gresley class P2 steam locomotive, dubbed
No 2007 Prince of Wales.
The Gresley class P2 2-8-2 ‘Mikados’ were the most powerful express passenger steam locomotives to operate in the UK. Designed by Sir Nigel Gresley, they were able to haul 600-tonne trains on the arduous Edinburgh-to-Aberdeen route. Six class P2s were built in 1934-36 but sadly the design was never fully developed. They were rebuilt by Gresley’s successor Edward Thompson into ungainly 4-6-2s in 1943-44 and scrapped by 1961 towards the end of the steam era in the UK.
PE visited the Darlington Locomotive Works to see the progress so far on the Prince of Wales and to find out how the trust plans to continue building the classic loco, with the aid of upgraded technology such as CAD, which was not available at the time of construction of the original P2s. The A1 Steam Locomotive Trust will fit the Prince of Wales with additional water capacity and the latest safety electronics to make it fully equipped for today’s mainline railway.
As the Gresley class P2s were never fully developed, the trust describes them as an ongoing enigma, which is one of the reasons why it has chosen to build one of them. Mark Allatt, chairman and founder of the trust, explains that the aim is to complete the development work as Sir Nigel might have done, building the seventh locomotive of its class. This will allow for improvements and variations in design to be incorporated.
Experimental design
“Only six P2s were built and each was slightly different because they were experimental and they were rebuilt during the war into rather unsuccessful differently designed locomotives,” says Allatt. “For this reason, they’ve always been a bit of a ‘what if?’ type of locomotive and have a lot of commonality with our first locomotive, the Peppercorn class A1, of which there were 49 built in the late 1940s. None were saved so we filled that gap by deciding to build the new one from drawings held at the National Railway Museum.”
The trust has decided to follow a pattern for the Prince of Wales set by the doyen of the class, No 2001 Cock o’ the North. So the new locomotive will have the original semi-streamlining and rotary cam valve gear and will look, to all intents and purposes, like No 2001. But the trust acknowledges that the original P2s had certain weaknesses, so the No 2007 will have these eliminated at the design stage.
David Elliott, director of engineering at the trust, says: “We have decided to set ourselves a new challenge: to develop, build and operate an improved Gresley class P2 Mikado steam locomotive for mainline and preserved railway use.”
In the Darlington workshop, Elliott has been working on the development of the Prince of Wales. So far, the trust has reached permanent assembly of the frame stays and brackets, and the forming and fitting of the footplating. “As sections of the footplating are finished, they are dismantled, grit blasted and primed prior to bolting on permanently,” he explains. “Grit blasting removes mill scale from the steelwork which saves many hours later when the paint finish is applied.”
The most significant item to have been manufactured recently is the smoke-box door. Tornado’s smoke-box door started life as a spun tank end which gave it a dished shape. The sharper radius on the outside edge of the door was achieved by hand forging over a former. Elliott says: “The D-shaped smoke-box door on the original P2 design does not lend itself to this method, although it would be technically possible to achieve it by cutting, blacksmithing and welding the round door. With the smoke-box door being both a prominent and iconic part of the P2 design, there was doubt that a satisfactory finish could be achieved by this method.”
Another method considered was CNC machining the door out of solid 8-inch thick plate, but this was more expensive than the method used. Having seen the quality and surface finish that South Devon Railway Engineering was achieving with firebox back heads, throat plates and tube plates, it was asked to quote for making the smoke-box door. After some discussion an acceptable quotation was received and male and female press tools were made using the 3D
CAD model.
Making sure that the locomotive is equipped for today’s mainline railway requires a change in focus from the original in the manufacturing process. The loco will have to meet current and foreseeable regulatory standards to allow it to operate as intended. Allatt explains that changes in design will emerge to cope with certain modern factors, such as water being at a premium nowadays. “They used to pick up water on the move when steam was the main source of traction on the railways but now we need to carry more water,” he says. “We can’t pick water up on the move any more because the troughs aren’t there to do it.”
The project’s use of the latest CAD software also provides a big change from former methods. It means that many aspects of building the locomotive can be simplified. Thanks to the use of CAD, for example, the weight of all of the components now in existence can easily be calculated. “The weight of the engine parts now in existence stands at 37.2 tonnes which is 39% of an estimated completed empty weight of 96 tonnes. The tender parts weigh 4.8 tonnes, 17% of an estimated completed empty weight of 28.4 tonnes,” says Elliott. “This gives a figure of 34% for the whole locomotive by weight, and this is much easier to calculate now with modern electronics.”
Lessons have been learned from building the Tornado.Allatt says: “Based on the positive operational experience with the electrical system fitted to No 60163 Tornado, design work is under way on a similar system for No 2007, making use of 3D CAD models to simplify and improve the accessibility of the conduits and trunking for the quarter mile of cable used.”
Provision is also being made to incorporate the European Railway Traffic Management System cab-based signalling system, with adequate capacity being designed in for future electrical demand. Another area of development is to produce high-intensity headlamps fitting into a traditional London and North Eastern Railway oil-lamp housing incorporating white marker and red tail lamps in the same unit. The class P2s were not originally fitted with any electrical system.
“3D CAD will be used all the way through the design process,” says Allatt. “This enables us to produce drawings that can be easily sent to the manufacturers. It also means that components are of an exceptionally high standard in terms of finish and accuracy and there’s not a lot of fitting needed.”
Other design differences will emerge in aspects of the loco such as the electrical system, which will copy the system fitted to the Tornado. Allatt says: “We need to have all the modern electronics on the Prince of Wales, which will need the equivalent of the railway black box and all of the electronics interfaces with the signalling and radios. We even have a mobile phone charger in the cab.”
Wired for steam
“All of that electrical equipment has to be fitted onto a locomotive that didn’t have any electrical equipment on it the first time around. The locomotive also has to be able to run on a railway that hasn’t been equipped for steam for over 50 years.”
The trust’s suppliers and contractors are already casting and machining a large number of castings for the frames, and design has been progressing on the larger fabricated frame stays. “As these are the subject of both a change in the manufacturing method and design in order to accommodate air brakes and steam-driven air pumps instead of the vacuum brakes fitted onto the originals, design justification that the original design worked satisfactorily is not enough,” says Allatt.
Building a locomotive is not cheap. The trust predicts that the Prince of Wales will cost
£5 million over a seven-year build period, taking the finish date to 2021.
The Prince of Wales is already more than one-third complete by weight. This rapid construction has been fuelled by the fundraising campaigns which have already seen pledges of 40% of the £5 million required. In only 18 months since the launch of the project’s “P2 for the price of a pint of beer a week” regular donation scheme, donations or pledges by standing order have been coming in steadily.
“Most of the money was raised from a large number of people giving a small amount on a regular basis,” says Allatt. “This formula worked well when financing the construction of Tornado but of course the price of beer has gone up since the first time.
“With that and some other schemes to sponsor components we have pledges of £2 million so far. We have the expertise, the track record and a plan, but this can’t happen without the help of our supporters.”
In Focus: 1930s predecessor
The seventh Gresley class P2 locomotive will be aesthetically similar to P2 No 2001 Cock o’ the North, allowing the trust to complete its goal of a construction and development project, rather than a major redesign. Fitted with additional water capacity and the latest safety electronics, No 2007 Prince of Wales will be fully equipped for travel on tomorrow’s mainline railways.