Pony truck delivered

We are delighted to announce that the pony truck frame has been delivered to Darlington Locomotive Works (DLW) following its fabrication by North View Engineering Solutions (NVES) in Darlington. The pony truck is a single-axle bogie which pivots towards the centre of a steam locomotive to enable it to negotiate curves more easily. We are also pleased to announce that construction progress has now passed with two-thirds point with around £3.4 million spent to-day and over three-quarters (£3.8m) of the estimated £5m required donated.

Despite the impact of COVID-19, progress on the construction of the new Gresley class P2 ‘Mikado’ continues to move forward rapidly. The engine has reached the condition where it is recognisably a P2 and the structurally complete tender tank and tender wheelsets are now at Darlington Locomotive Works. Construction and assembly work continue on all fronts, including boiler, wheelsets, tender frame, heavy motion, pipework and electricals. Design work for the extensively modified and improved cylinder block is complete, with the focus now turned to adaptation of the Lentz rotary cam poppet valve gear to further improve the original design.

The redesign of the pony truck is one of the four principal areas of redesign identified by the project team before the launch of the project to build an improved Gresley class P2 in 2013:

  • Develop improved pony truck and frame design using VAMPIRE® modelling data to confirm ride characteristics – completed
  • Investigate and confirm valve gear to be fitted – choices were improved Lentz/Franklin, Walschaerts or British Caprotti; Lentz/Franklin was the final choice
  • Investigate and reduce risk of crank axle failure apparent in original design – completed
  • Investigate and confirm design and method of construction of cylinders (cast versus fabrication) including Computational Fluid Dynamics (CFD) study.

No. 2007 will incorporate a modified leading pony truck to avoid the issues that afflicted the original class P2s in this area.  The LNER solved a similar problem with the Gresley class V2s using its experience from building Stanier 8F 2-8-0s at Doncaster Works during WWII. The Trust therefore commissioned DeltaRail (now Resonate) to use Vampire® software to construct a ‘virtual’ class P2 and analyse the performance of the original Gresley swing link suspension design and modified pony truck using side control springs. The Trust’s design team then used the results of the Vampire® modelling and the revised class V2 arrangement to redesign the pony truck for our new class P2 using side control springs and incorporating roller bearings.

The construction of the pony truck took place at several sites across the UK. The wheelsets were assembled – using two 3ft 2in wheels cast by the Trust’s principal sponsor William Cook Cast Products Ltd of Sheffield – by South Devon Railway Engineering at Buckfastleigh and delivered to Darlington Locomotive Works in September 2018. Since their arrival, the wheels have been filled, painted and polished in preparation for the fitting the cannonbox.

The pony truck frame was fabricated by North View Engineering Solutions (NVES) in Darlington. Now that the pony truck frame has arrived at DLW, the next steps include continuing the Finite Element Analysis (FEA) study for approval of new design, manufacture of spring gear details, final assembly of the cannonbox onto the wheelset and the machining of the spring planks & bearer cup and spherical side bearers.

In April 2020 the Trust announced that it had launched a new £20,000 appeal – The Pony (Truck) Club – to fund the manufacture and certification of the leading pony truck for No. 2007 Prince of Wales. We set a minimum target of 20 generous supporters willing to donate £1,000 plus Gift Aid (in up to four payments of £250) but this mini-club galloped away and soon passed its initial target. We therefore decided to extend the club by a few members to cover the considerable certification costs associated with the modified pony truck design.

Steve Davies MBE, Chairman of The A1 Steam Locomotive Trust, commented, “The delivery of the pony truck frame to Darlington Locomotive Works is yet another key milestone in the £5m project to build new Gresley class P2 No. 2007 Prince of Wales. It is a testimony to the forward thinking of our engineering team that some of the original research was conducted during No. 60163 Tornado’s testing on the Great Central Railway in 2008, five years before the formal launch of the project.

“Fundraising is also moving forward well. The ‘P2 for the price of a pint of beer a week’ Covenant scheme has already attracted 940 Covenantors, and with over £3.4m spent and more than £3.8m donated to-date of the estimated £5m required, the project remains on-track for completion within three years.

“We are delighted with the support the project to build Britain’s most powerful steam locomotive has received since its launch more than seven years ago. However, to maintain this progress we need to raise £700,000 per year and we are still seeking to recruit an additional 60 ‘P2 for the price of a pint of beer a week’ regular donors or covenantors. In time for the 60th anniversary of the disposal of the last former Gresley class P2 No. 2002 Earl Marischal – as Thompson class A2/2 No. 60502 – in July this year.”