The A1 Steam Locomotive Trust celebrated another major milestone in the construction of Gresley P2 No. 2007 Prince of Wales at its Summer Supporters’ Day, as the locomotive’s three-cylinder monobloc was successfully lowered into the frames before an audience of supporters whose generosity continues to drive the project forward.
Manufactured by Howco Ltd of Ayrshire, Scotland, the fabricated monobloc is one of the most complex components of the new locomotive. Its design was led by the Trust’s former Engineering Director, David Elliott, who refined Sir Nigel Gresley’s original concept to overcome several known shortcomings. Improvements include balancing the clearance volumes between the cylinders and reducing heat transfer between inlet and exhaust steam, creating a more efficient and refined design while remaining faithful to Gresley’s vision.
Poignantly, David did not live to see this landmark achievement, having passed away in late 2023. His meticulous engineering and attention to detail ensured the installation proceeded exactly as intended, providing a fitting tribute to his immense contribution to the P2 project and to railway preservation more widely.
Earlier this year, Darlington Locomotive Works took delivery of its 15-tonne overhead crane, which undertook its first major task in lifting the monobloc into position. Supporters attending the Summer Supporters’ Day witnessed the final stages of the operation, marking a memorable moment in the locomotive’s construction. The next phase will see the assembly checked for alignment before fitted bolts are installed to secure the monobloc permanently within the frames.
P2 Project Director Richard Courteney-Harris said:
“This has been a major engineering challenge and is probably the first three-cylinder monobloc to be installed in a main line steam locomotive for more than 60 years, if not considerably longer. The team at Darlington Locomotive Works should be immensely proud of this achievement as they continue to build upon the legacy of David Elliott’s talent and vision. During this 150th anniversary year of Sir Nigel Gresley’s birth, it is especially fitting to recognise the foresight and ingenuity of two remarkable engineers whose work has shaped this locomotive.”
The monobloc has been designed to work with the P2’s innovative rotary cam poppet valve gear, based on the Lentz system and developed by David Elliott. Full-size 3D-printed prototypes of the cambox have already successfully demonstrated the design, paving the way for manufacture of the final metal components.
With this latest milestone achieved, No. 2007 Prince of Wales continues its steady progress towards completion. From just £10 per month, Covenantors are helping to fund the manufacture of the locomotive’s innovative valve gear and bring Britain’s most powerful new steam locomotive ever closer to steam. Supporters can also help maintain the momentum by joining 'The Valve Gear Club'.
If you would like to play your part in completing No. 2007 Prince of Wales, click here and be part of the journey.
Photo credits: A1SLT/Paul White/Michael Sanders