Black Prince – the remaining work

Black Prince - David Shepherd’s 9F class heavy freight locomotive no. 92203 - is being rededicated on Monday 18 October at Toddington. However, the locomotive is running just one trip from Winchcombe to Toddington. The other services will be hauled by Great Western heavy freight tank locomotive no. 4247, built in 1916 - more than four decades earlier than Black Prince.

Here are a few questions and answers about Black Prince and its return to steam.

Why is Black Prince only running one trip?
Although it has just undergone the first major overhaul since it was built in 1959, some work still has to be completed. After taking professional advice, it has been decided to run the locomotive as little as possible until this work can be done.

Why are you taking such care?
The main task remaining is to fit new tyres to the rear set of driving wheels because the flanges, which guide the locomotive along the line and round curves, are worn. The tyres, which include the flanges, are made of special steel and separately fitted to the wheels. There is some work remaining on the boiler as well.

Why should just the rear driving wheels become worn?
Black Prince, like other tender locomotives, is designed to travel mainly in the forward direction. The locomotive was withdrawn from service on British Railways in 1968 and, since then, it has worked almost entirely on heritage railways such as the Gloucestershire Warwickshire Railway. This means that in the absence of turntables the engine must run in reverse as much as it runs forward. When running in reverse, the rear driving wheels take the brunt of wear when the locomotive is negotiating curves. The sharper the curve, the greater the wear. There isn’t this problem when running forwards because the leading ‘pony’ wheels are designed to help the locomotive negotiate curves. Black Prince has run up several thousand miles on heritage lines - half of it in reverse.

Why are worn flanges a problem?
Because if they wear beyond a certain amount, there is a very remote possibility that the rear driving wheels could lift against the rail, which could damage both the rear wheels and the track. We feel that it is better to be absolutely safe and avoid this possibility completely.  David Shepherd is aware of the problem and agrees that this is the best option.

How will Black Prince get to Winchcombe?
It will run ‘light engine’ - that is, without any coaches - in the reverse direction. We can do this in complete safety by avoiding sharp curves and taking the journey gently. There is no problem with the locomotive running forwards.

If you can do that, why couldn’t you take the engine to Cheltenham Race course - we would have got a longer ride then.
Until our signalling is operational at Cheltenham (expected by March next year) we cannot have two separate train or locomotive movements at the same time beyond Winchcombe.

What happens to Black Prince next?
It is likely that the rear wheel set (the two wheels complete with the axle) will be removed at Toddington and then taken away for the specialist re-tyring work to be done. Another possibility is that the engine is taken away complete to a specialist contractor.

How long will the work take?
That is difficult to estimate with accuracy because the old tyres must be removed and new ones manufactured specially to fit the wheels. Tyre manufacture and fitting is a highly specialised job. Once fitted (by heating the tyre to almost white heat so it expands and can be slipped on to the wheel; the tyre is then rapidly cooled so it shrinks on to the wheel) it must be machined to the correct profile. We believe that at the earliest, the locomotive will be back in working order in about April or May.

Isn’t this a blow for David Shepherd and for the GWR?
Yes, it is. Although the wear was known about before it left the GWR for overhaul, it was not possible to get the work done ahead of its return to steam.

Hasn’t the locomotive already run up some mileage on another railway, running in before it came back to the GWR?
Yes, it has. However, we don’t believe the degree of wear was fully appreciated while it was running in and, already being worn, the rate of wear has probably accelerated. We feel that to be absolutely certain it is best to replace the tyres that have the worn flanges.

How long will the new tyres last?  And what about the rest of the wheels?
One option is to replace all of the tyres (all 10 of them!) now. However, this will be significantly more expensive and, in any case, we are advised that the locomotive will see out its 10-year ‘ticket’ before its next overhaul simply by replacing the rear tyres.