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| Tangmere incident, causes and recomendations https://www.rypn.org/forums/viewtopic.php?f=1&t=36751 |
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| Author: | Trevor Heath [ Mon Jun 16, 2014 9:48 am ] |
| Post subject: | Tangmere incident, causes and recomendations |
http://www.raib.gov.uk/cms_resources.cf ... hfield.pdf |
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| Author: | softwerkslex [ Mon Jun 16, 2014 10:37 am ] |
| Post subject: | Re: Tangmere incident, causes and recomendations |
31 surviving examples! |
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| Author: | sbhunterca [ Mon Jun 16, 2014 11:02 am ] |
| Post subject: | Re: Tangmere incident, causes and recomendations |
One of those seemingly "no-brainer" redesigns that can seriously bite one in the rear end. Thank goodness the incident ended with minimal damage and no injuries. Steve Hunter |
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| Author: | Dave [ Mon Jun 16, 2014 11:54 am ] |
| Post subject: | Re: Tangmere incident, causes and recomendations |
The interesting thing is they don't actually know what happened. All the recommendations are probably well founded, but none deal with immediate problem, whatever it may have been. The thing about the dead battery in an event recorder that couldn't have recorded the failure of a bit of metal is of no consequence, but it takes up a lot of bandwidth. I'm also very interested in the justification of the rationale that the loose piston on the rod was an effect rather than a contributing cause. dave |
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| Author: | robertmacdowell [ Mon Jun 16, 2014 1:09 pm ] |
| Post subject: | Re: Tangmere incident, causes and recomendations |
softwerkslex wrote: 31 surviving examples! With so few extant, thank God and Queen that none have been permitted to leave the UK. |
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| Author: | Alexander D. Mitchell IV [ Mon Jun 16, 2014 1:56 pm ] |
| Post subject: | Re: Tangmere incident, causes and recomendations |
Some of the extant examples referenced are in not much better shape than, say, the "Lost Engines of Roanoke" were. At least two probably qualify as "parts sources only;" one was sectioned for display at the National Railway Museum; a couple at Woodhams Barry were scavenged for spares before being broken up as I recall; and a couple have been "under restoration to mainline service" about as long as PRR 1361 has been out of service, if not longer...... and at least one was reported, years ago as a case of "we're waiting for them to clap out all the other ones afore we put THIS one in service...." Frankly, if any British steam loco class had enough extant examples to spare an example for export, it would have to be either a Bulleid Pacific or a Stanier "Black Five"...... |
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| Author: | softwerkslex [ Mon Jun 16, 2014 4:56 pm ] |
| Post subject: | Re: Tangmere incident, causes and recomendations |
I bet when the main rod dropped the piston slammed back and forth in the cylinder and knocked the piston rod loose. Amazing it did not pop either cylinder head. |
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| Author: | Bobharbison [ Mon Jun 16, 2014 5:33 pm ] |
| Post subject: | Re: Tangmere incident, causes and recomendations |
I'm impressed with the report, seems detailed, but fairly easy to read. Thorough, but not so huge that nobody will read it. All in all, well done in my opinion. Does anyone disagree with the conclusions they reached? I agree that the event recorder most likely would have had nothing useful, but understand why they're disappointed that it wasn't working, just in case, and the comments regarding maintaining them are useful in case of future events where they may be useful. softwerkslex wrote: I bet when the main rod dropped the piston slammed back and forth in the cylinder and knocked the piston rod loose. Amazing it did not pop either cylinder head. I'm trying to picture what would happen. Is it going to continue slamming back and forth due to the steam flow being controlled by the eccentrics, and the fact that the rest of the system acts as if the piston rod is still there? Or can it get to such an extreme end that it's past the steam port and thus is pinned to one end or the other by steam pressure? Also seems like the force of it dragging would pull it to the back of the cylinder, but that would easily be overcome by steam pressure. |
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| Author: | Dave [ Mon Jun 16, 2014 6:26 pm ] |
| Post subject: | Re: Tangmere incident, causes and recomendations |
Bob, it happened at MRSR if you recall....the Heisler had a knock that was caused by the bolt holding the piston onto the rod having loosened, allowing the piston to be driven by the steam to either its seat on the rod or against the bolt at each stroke. That's the first thing Jack asked me to work on up there during the triple header event. So....did the loose piston shake the rod loose, or did the loose rod shake the piston loose, or were there additional problems that shook both loose? Maybe they aren't related at all...... dave |
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| Author: | dinwitty [ Mon Jun 16, 2014 6:41 pm ] |
| Post subject: | Re: Tangmere incident, causes and recomendations |
will you please at least post some text from this pdf? usually when posting links, your sent to news places that mass ads or other content, keeping the link but copying text over keeps the copyright intent intact, making an easier read on the board. anyways I got the pdf Dled and looked. The first hint of noise they should have stopped and inspected. The problem was already starting. It seems to me there may have been poor lube on the contact surfaces, the motions forced the pin to turn incorrectly breaking the cotter pin, spinning the nut. The forces eventually wound the nut off. I think the cotter pin is far too weak for this arrangement, it needs a solid pin thru that then you can cotter both ends of the pin. With the explanations it may seem there may have been improper seating design of the matching surfaces. You would have eventually metal grinding on metal no grease would solve that. If a metal shard winced out you would have had that clocking turning motion that spun your nut off. It might be a good idea to weld/install some drop loops under the piston area so it wont drop down like that if anything happens like this. But it may not make any differrence if it happened to a double over/under slider it would have popped out and dropped below anyways. They better check the other side piston as well. |
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| Author: | eze240 [ Mon Jun 16, 2014 8:24 pm ] |
| Post subject: | Re: Tangmere incident, causes and recomendations |
I recall experiencing a Heisler having such a failure a few years ago.... The Rod end on the firemans side cylinder had been knocking a bit....it grew worse as the trip progressed.... We were doing all of 15 mph, working up a small grade, with three heavy passenger cars... As I recall, there was a rather loud Ka-bang, accompanied by the rod end flying out from under the loco.....rapidly, almost instanly followed by a loud Pop-pow-bang......including a sizeable cloud of hot steam and some metal fragments flying into and past the cab.....out of the corner of my eye, I saw the cylinder head cover fly past the cab door..... Really quite exciting....the fireman came out of his seat and nearly jumped out the door.... After stopping, we looked it over and noted the cylinder head was basically shattered, the end of the piston rod going thru it and a series of cracks running outward, dividing the head into about five wedge shaped pieces..... The rod end had been beaten apart....probably due to the bearing having been worn beyond the wedge adjustment limits.... |
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| Author: | Alexander D. Mitchell IV [ Mon Jun 16, 2014 9:16 pm ] |
| Post subject: | Re: Tangmere incident, causes and recomendations |
dinwitty wrote: The forces eventually wound the nut off. I think the cotter pin is far too weak for this arrangement, it needs a solid pin thru that then you can cotter both ends of the pin. Examine Paragraphs 39 and 40 and Figure 6. They HAD a solid pin. |
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| Author: | Kelly Anderson [ Mon Jun 16, 2014 9:20 pm ] |
| Post subject: | Re: Tangmere incident, causes and recomendations |
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| Author: | dinwitty [ Mon Jun 16, 2014 11:02 pm ] |
| Post subject: | Re: Tangmere incident, causes and recomendations |
Alexander D. Mitchell IV wrote: dinwitty wrote: The forces eventually wound the nut off. I think the cotter pin is far too weak for this arrangement, it needs a solid pin thru that then you can cotter both ends of the pin. Examine Paragraphs 39 and 40 and Figure 6. They HAD a solid pin. your confused what I am trying to say. A cotter pin is holding the nut to prevent turning, I am saying in repair, just put a solid pin thru, drill holes on the ends of the pin and pop cotters thru (smaller ones) to prevent the pin from popping out. I was thinking about this design, why isnt there brass bushings in this? -nudder edit- it may have been economics designed, a brass bushing would have worn in and taken the tearing/wearing and not the hard metals, which is why many american engines had the brass washer bushings, and the weardown gives you that regular rod clanking we all know and hear. This accident would never happenned with brass bushings. They will need to watch lubrication very closely. |
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| Author: | Kelly Anderson [ Tue Jun 17, 2014 8:54 am ] |
| Post subject: | Re: Tangmere incident, causes and recomendations |
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