Front-enD changes to Be incorPorateD into 71000 oVerhauL
Duke of Gloucester is to receive front‑end modifications to improve its reliability for main line operation. As part of its overhaul at Tyseley Locomotive Works, Bob and Alistair Meanley have reviewed the design of the unique Riddles ‘Pacific’s’ pistons, front and rear cylinder covers and slidebar fixing arrangement, along with the cylinder lubrication system. Trevor Tuckley, chairman of the BR Class 8 Steam Locomotive Trust, explains that the changes will address the problem of heavy piston ring wear, and hence loss of steam tightness, an issue that No. 71000 has in common with other BR Standard locomotives owing to flaws in the design. The slidebars will now be attached to the rear cylinder covers, instead of being mounted solely on brackets from the frames – a feature common to all the larger Standard designs except for the Caprotti‑geared ‘5MT’ 4‑6‑0s. However, says Mr Tuckley: “It was mainly a lubrication issue – the different slidebars didn’t completely cure the problem. Cowlairs Works found that the piston ring wear on the Caprotti ‘Standard Fives’ was only slightly better than those with Walschaerts gear.”
The latest progress on the overhaul was due to take place on August 8 with the trial‑fitting of a new cam into the locomotive’s centre cambox.
Writing for the trust, train timers Doug Landau and David Pawson commented: “There are still ways to move the design forward. Reliability is crucial in today’s world, and so is the need to develop top power in less favourable circumstances. “The aim of this rebuild is to create a ‘Duke’ that fulfils all its designer’s intentions in terms of performance and reliability and it will incorporate new best practices needed for the 21st‑century main line. The rebirth of the ‘Duke’ from a rusting hulk has proved a magnificent example of restoration and technical advancement but there is more that can be done. “Given the opportunity for another main line innings, the best may be yet to come. The evolution of the ‘Duke’ is not complete. It will look perfect in its original 1954 livery, but inside it will be a different beast.”