Christmas pic Edward Thompsons little known V5

[52D]

Perhaps a propensity to derail led Edward Thompson to abandon his V5 class rebuilds in Favour of the A2s here Waverley lies in the ballast looking like a 2-6-2 after losing a splitpin then half its valve gear at Goswick 1953.

[S.A.C. Martin]

So in context - what caused the derailment?

Struggling to understand the point you are making.

[mick b]

What is a V5 ? perhaps a V2 . The A2/1 was never a V2. Thompson never built/designed the A2, they were designed by Peppercorn.
The Valve gear also looks intact in the photo?

[mick b]

Bit more than a split pin falling out. Accident caused by failure of retaining bolts on centre eccentric strap of valve gear which then fell downwards and then colllided with a set of points.

http://www.railwaysarchive.co.uk/docume ... ck1953.pdf

[52A]

That was rather lost on some 52D!

[John Palmer]

Coincidentally this derailment occurred at the same points as those involved in the 1947 accident.

This incident was attended by a fortunate outcome. Contrast with the accident near Settle in 1960 when a Britannia dropped its bottom right hand slide bars. In effect, the locomotive pole vaulted its connecting rod so that this came to rest trailing the crankpin. The relevant report can be found at http://www.railwaysarchive.co.uk/docume ... le1960.pdf.

The drawings used to illustrate the report include a couple of errors, one of which is pretty fundamental!

[52D]

Yes John I have heard of the accident with the Brit being similar I will have to read up on it. Perhaps I should have kept the pic till April 52A.

[Boris]

Of course the motion looks o.k but I bet the other side looks a bugger

[S.A.C. Martin]

From the report:

19. l am satisfied that the main components of the valve gear of the centre cylinder were in good
order when the engine left Haymarket Shed to work the train. There was no weakness in design or flaw
in the material, and 1 believe the accident occurred because two nuts on the top bolt of the eccentric strap
became unscrewed during the journey. This could not have happened if there had been a properly fitted
split pin through the bolt outside the lock nut, and even an undersized one should have checked the
unscrewing of this nut. Furthermore, a properly fitted pin could not have fallen out on the journey, though
an undersized one might have done so if the legs had not been sufficiently splayed. I conclude therefore
that there was not a properly fitted split pin in the top bolt of the eccentric strap when the engine was
examined at Haymarket Shed before the trip, though there may have been an undersized one which
subsequently fell out.

20. It was suggested to me that the stripping of the thread of the top bolt might have been caused
by excessive pressure which forced off the nuts and sheued the split pin. However, tensile tests to
destruction with similar bolts with only one nut caused the shank to elongate and break under a pull of
48 tons; the threads were undamaged after the tests and the nut still free to turn. A properly designed
thread and nut should of course produce this result, which disproves the suggestion unless the threads of
the bolt and nuts had been badly worn. As the nuts were lost and the bolt much damaged and rubbed,
the wear in the threads before the accident occurred could not be assessed, but I have no reason to believe
that the bolt and nuts would have been allowed to get into so unserviceable a state.

REMARKS

21. I visited Haymarket Shed shortly after the accident in order to see how an examining fitter made
his inspection of an engine. I found that though the inspection seemed thorough, the attitude towards
split pins was far from meticulous. Undersized split pins were not booked and I was told that they were
sometimes fitted because a lock nut masked the split pin'hole after adjustment or repair. I found no evidence
that the supervising staff insisted on the proper practice of nuts being fitted so as to bring the face level
with the edge of the split pin hole, either by using a washer or turning or filing down the nut.

22. A derailment at Brownhill Junction, Dalry, on 17th September, was also caused by the falling
out of an undersized split pin fitted at Kingmoor Shed during the adjustment of tender brake gear, and
carelessness in the fitting of split pins was responsible for three accidents on British Railways in 1952.
Although only 2 - 3 per cent of the accidents reported to the Minister each year are attributable to locomotive
defects, it may he desirable to impress on all concerned once again that inattention to detail in
fitting and examining work at the sheds may have very serious consequences.

23. It happened that this derailment occurred at the same facing connection as the one on the 26th
October, 1947, but the cause was different. The less serious consequences on this occasion may be ascribed
to the fact that the train was not diverted from a straight path and the coaches therefore maintained their
alignment.

So the locomotive's design was not at fault, according to an independent report, and again I find the standard of maintenance at one of the Scottish sheds to be in question regarding the Thompson Pacifics.

One wonders how many times these myths regarding Thompson's Pacifics will pop up for the single purpose of denigrating the designer. In this case the locomotive's design was not at fault, nor was the crew or permanent way staff. I wonder how many of the numerous shoppings the Thompson Pacifics apparently suffered was down more to inadequate maintenance than their supposed flaws? We shall never know for certain but I wonder if this happenstance is pointing towards a different way of thinking.

[Andy W]

I think this thread was meant to be a humorous one, not intending to denigrate. It seems to have been lost on some, possibly because of the dry nature of the humour! I got it and I am a fan (sort of) of Thompson.

However, the subject of nuts and split pins on pacifics is far from humorous at the moment, especially at the RAIB.

[manna]

G'Day Gents

I think it proves that 00 gauge trains won't run on EM track !!!!!!!!!

manna

Merry Christmas to all.

[Blink Bonny]

Ay up!

Thanks for putting us back "on track" Manna!!!!