Tangmere

It is also possible that the RAIB website is not completely up to date. However, you may be right and they (RAIB) don't formally investigate. The ORR may do so, or it may be left to NR and WCRC. Much depends on what they find in the early stages of their investigation as to who ends up with the responsibility. This was a serious incident and a very near miss to something even worse. No doubt those most closely involved will want to know what happened, and the rest of us will have to wait and see.

 

I'm sure that the ORR will have had some discussions on this with WCRS. However, it is quite common for the ORR to let the organisation concerned carry out its own investigation and await their findings before considering further actions.

 

Yep. Am aware of how it works.....I chose the wording in my post very carefully.

 

Not teaching you to suck eggs, just emphasising what you said and adding a bit! I'm sure that a lot of people on here will have no idea of how these things work - but others will.

 

RAIB have only just announced an investigation into a fatality on October 26 so taking 4 to 5 weeks to prepare the incident notice

 

RAIB have just announced the investigation in to Tangmere's incident:
http://www.raib.gov.uk/publications/current_investigations_register/131123_winchfield.cfm
The thing that stuck out straight away is that the pin was found intact on the loco, but the nut etc haven't been found. This just seems odd to me as even though I have no experience with locos, from a boating experience which I have decades of experience, split/gudgeon pins are a weak link so to speak & will be the part most common to break & then disappear never to be seen again!

 

The report actually says

It was the gudgeon pin that was found, not the split pin or cotter that secures the nut. The gudgeon pin is the large cylindrical lump that passes through the little end bearing and is not usually prone to failure. Probably it worked loose and fell out, but mustn't speculate.

 

No speculation that it came out and was found on the bogie splasher. It is mentioned in the RAIB synopsis, although it doesn't actually mention the splasher, as such. I'll disagree about gudgeon pins not being prone to failure; there have been several. Along with crankpins and many other items, they need routine NDT.

 

Fair enough Steve, I've never experienced or come across any reports of actual gudgeon pin failure myself.

 

Ooof. It sounds as if the conductor rail actually prevented a much worse incident... Gudgeon pin found intact. Hmm.

 

Haven't come across any actual gudgeon pin failures in steam locos either, have you got any examples of such Steve? It would be interesting to know what, when, where and how they failed (where being where the pin failed). I can see that a gudgeon pin is subject to sheer force and this could include some shock loading when wear occurs but not having come across one I would be interested to know if there is a particular weak area that needs checking.

 

At the NYMR 60007's pin failed whilst on steam test a good while back, fortunately without any incident. NDT of other locos found that one of 825's pins was seriously flawed and replaced. (Might just have got the wrong loco, it was a while ago.) These were both fatigue failures; these pins are subject to stress reversal on every piston stroke so a prime possibility of fatigue failure. I think that the line of failure was at the thread root in both cases; I didn't actually see them at the time. However, they again cropped up in conversation whilst we were discussing the recent happening with 34067.
As I said earlier, these and crankpins are subject to routine NDT. on the NYMR. I think annually.

 

I see that they are asking for photos and videos of the run from Waterloo showing the loco's right side to be sent in to help with the investigation. There must be a few around.

 

Steve, did 60007 fail catastrophically, or just crack at one end? Mind you on the main line you'd be unlikely to detect a crack until it became a total failure.

 

Yes just noted this on the website :

Request as under :

The RAIB’s preliminary examination found that the small end assembly, in which the connecting rod is secured in the crosshead by a gudgeon pin and associated nut and cotter, had come apart. The gudgeon pin was found intact, lodged on the locomotive, but the nut and cotter have not yet been recovered.
The RAIB’s investigation will seek to identify the sequence of events leading to the connecting rod becoming detached. It will include the design, manufacture, installation and maintenance of the components making up the crosshead and piston assembly, and relevant aspects of the operation and maintenance of the locomotive.
The RAIB would be pleased to hear from anyone who has a photograph or video recording showing detail of the right-hand side of Tangmere, taken at Waterloo or subsequently on the journey during the evening of Saturday 23 November.

 

Not 100% sure as I wasn't there but I believe that it broke whilst being check tightened. A bit like, oops, it came off in my hand!

 

Aaaaaarrrrrggggghhhh!!!!!!

Read the RAIB report. The gudgeon/small end pin did not fail. The nut came off.
Please stop speculating that the small end pin failed. Unless your are unable/ unwilling to read the RAIB preliminary report........

 

I don't think that Steve was suggesting that Tangmere's gudgeon pin had failed was he? I thought he was illustrating that it wasn't unknown through an example?

Regarding Tangmere, presumably the request for photos is to try to discover at what point the slit pin and nut ceased to be present. I guess it is possible it could be some distance from the point where the gudgeon pin came out, and the rod fell to the ground.... like miles. Does seem to have been a narrow escape from a very nasty accident.

 

Aaaaaarrrrrggggghhhh!!!!!! Why don't you read the thread from #107 ??????????

 

More than that, if they possibly can they'll want to find every missing component to evaluate exactly what sequence of events led to the failure. Marks on each piece will have a story to tell. If you've never done so its worth reading through a couple of RAIB reports that deal with some kind of mechanical failure to get an idea of how these things are done. Warning, you do need to read *all* to get a good picture. While the format is desperately repetitive (curse of the word processor era), there is important stuff scattered right through the documents.