måndag 21 december 2009

Obsolete technology?

You need to listen hard. There is something very odd about 71000, the Duke of Gloucester, which sounds different from any other steam locomotive: the exhaust sound is soft and almost perfectly regular, sometimes described as a "chatter", and presumably due to the special valve gear with which it is fitted. The video shows it pulling hard - probably flat out - up the notorious Wellington bank. It also shows that there is surplus steam which is being released from the safety valves.

As part of the programme of research, upgrades and remedial work which the owners have been engaged in ever since the locomotive was removed from the scrapyard in the early 1970s, it is presently undergoing further modifications to remedy yet another manufacturing error. This fault apparently meant that the centre of the three cylinders has only been producing half the power it ought to, so that the locomotive is only running at 5/6th of its potential. Since, this defect notwithstanding, the locomotive was, until the arrival of the 3,690 hp class 70 freight diesels,  probably the most powerful in Britain, with a maximum output of around 3500 IHP, the results of this latest upgrade should be interesting, with a theoretical output of 4,200 IHP.

The video below shows it climbing another notorious bank, Shap, on the West Coast Main Line. Again, the smooth regular exhaust sound is noticeable. Also noticeable at the end of the video is the black smoke indicating incomplete combustion, which remains an occasional feature of the locomotive and suggests that there is further potential for improvement.

This is not what one would expect of an obsolete technology in its dying stages. It makes one wonder if the most useful thing the DfT could do would be to fund the < £500k it would cost to resolve the remaining problems, and then arrange with one of the ROSCOs for the purchase of a entire fleet, plus the construction of the supporting infrastructure of water supply, turntables, etc, for use on main lines which are never likely to be electrified. It also raises two further questions: whether a streamlined version should be built, with a wedge-front casing somewhat in the style of an HST, and whether a small-wheeled freight version would not be better value for money than any diesel. It certainly does not sound as if the technology should be confined to the museum just yet.

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