Design & Development | About Prince of Wales | Prince of Wales

Design principles

In much the same way that Tornado was constructed as the 50^th A1 rather than a replica of the original members of the class, No. 2007 will be the 7^th member of the P2 class, likewise allowing for improvements and variations in design.

The decision to closely follow the pattern set by Cock o’ the North means that the locomotive will have the original streamlining and featurer rotary cam valve gear and will look, to all intents and purposes, like No. 2001. However, the Trust acknowledges that the original P2s had certain weaknesses and No. 2007 will have these eliminated at the design stage. The team is using modern computer-aided design and modelling techniques that obviously weren’t available to engineers in the days of LNER to assist these developments. This has been an extremely exciting process. You can find the full design study here.

Some of the main components that have evolved from the original designs include:

Frames

The ‘foundation’ of any engine will incorporate a modified leading pony truck to avoid the issues that afflicted the original P2s in this area. The L.N.E.R. solved the problem when the V2s showed a similar tendency and computer modelling can be used to re-design a more stable arrangement. DeltaRail used the ‘Vampire’ programme to construct a ‘virtual’ P2 and analyse the performance of a modified front truck.

Wheel sets and running gear

Casting a full set of wheels and the forging of axles are processes the Trust is already familiar with. It has been decided that unlike the originals, No. 2007 will have roller-bearings throughout – our experience with those fitted to No. 60163 has vindicated the choice for that loco already. Many of the patterns are common the both Tornado and No. 2007 and thus save a lot of expense, indeed a spare cannon box was already in stock!

Cylinders and valve gear

The idea to model No. 2007 on Cock o’ the North meant that rotary valve gear was inevitable. Some changes have been made to the proportions of the cylinders to compensate for the increased boiler pressure available from the 250lb/sq in diagram 118A fitted to Tornado. However, the Lentz gear used on the original offered only limited cut-off settings and may have contributed, in part, to No. 2001’s high coal consumption. The Trust looked at British Caprotti valve gear using a derived drive for the centre cylinder; this valve gear was perfected in its application to No. 71000 Duke of Gloucester and offers infinitely variable cut-offs, although the 71000 SLT is still developing and refining the gear. In the end the availability of drawings and technical specification for the Franklin derivative of the Lentz meant it was decided to follow this route, incorporating the improvements made in the U.S.A. into the valve gear. David Elliott explains the challenges here.

Boiler

This major component is one of the most powerful reasons that the Trust is considering a P2. Although the original class had 220lb/sq in boilers the overall size is identical to the diagram 118A 250lb/sq in boiler fitted to No. 60163, thus giving the option to inter-change this component at overhauls. Although the internal design is slightly different to No. 2001’s boiler, the precedent was set by No. 2006 Wolf of Badenoch which had a boiler with a firebox combustion chamber. This increase in thermal efficiency should also help to alleviate the high coal consumption noted with Cock o’ the North.

Tender

The tender is almost identical to that used by Tornado, featuring the modifications that allow more water and slightly less coal to be carried. It will run on roller bearings with spoked wheels (the pattern for these being held by the Trust), only the addition of beading to the tank will make the design different.

Ancillaries

Braking follows the design perfected during the construction of No. 60163, primary air brakes for locomotive and train with secondary vacuum brakes for working preserved stock. The electrical system will copy the excellent system fitted to Tornado although the original P2s did not have a Stones generator or electric lighting.

The P2 project already had head start in the vast number of common components the locomotive shares with Tornado, many patterns for which are held by the Trust. However, no metal was cut until the results of the computer modelling were known and we were sure that the design was acceptable to Network Rail.