What does the term rebuilt mean

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Bigmet
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Re: What does the term rebuilt mean

Postby Bigmet » Thu Aug 09, 2018 1:19 pm

flying scotsman123 wrote:...I am very much not an expert in this, but I have been reading with some interest the discussions between those who are, who seem to have come to the opposite conclusion, backed up by original LNER data here.

I promise you the guy behind that analysis is not an expert of any sort.

To get the story straight.

The P2s were a problem class, and needed a lot more development to iron out their deficiencies, for which there was not the resource in wartime. Probably the best thing to have done with them was base them at Doncaster where works attention was more readily available, and use them on the ex-GN route with its easy curvature to handle the large wartime loads.

Thompson's rebuilding produced a better machine in terms of availability. However not so good as the previously constructed pacifics, and with a reduction in tractive capability compared to the P2. Same again with the four last V2s ordered, completed as A2 pacifics, and the A1/1 rebuild ; inferior to the A3 and A4 pacific designs in performance and availability and there's ample evidence for that. The Thompson pacifics ran smaller mileages, ended up based in secondary locations rather than principal depots, and had greater repair cost than the previous pacifics, and went to the scrapper earlier ahead of much older locos.

There was nothing wrong with the principal components of the Thompson pacifics, they were all Doncaster standard parts as developed under Gresley, just the arrangement of the wheelbase which Thompson required because he had an obsession for equal length connecting rods above all other engine layout considerations. Peppercorn arranged the same components on the established conventional wheelbase layout, and these performed perfectly well; and in the case of the A1 were probably the most reliable express traction BR had.

Thompson got it badly wrong in short when it came to his pacifics.

With a new P2 being built and a lot more experience and analytical tools available, it will be interesting to see just what emerges.

b308
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Re: What does the term rebuilt mean

Postby b308 » Fri Aug 10, 2018 8:54 am

Pity the poor sod that had to clean out the ashpan at the end of the day, though!

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flying scotsman123
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Re: What does the term rebuilt mean

Postby flying scotsman123 » Fri Aug 10, 2018 10:42 pm

Bigmet wrote:I promise you the guy behind that analysis is not an expert of any sort.


Maybe not, but he's put himself up to an awful lot of scrutiny from people who can have meaningful conversations about these things (unlike me)!
"listen carefully, i shall say this only once"

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Bigmet
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Re: What does the term rebuilt mean

Postby Bigmet » Sat Aug 11, 2018 11:50 am

It's a cult thing: 'Thompsonism'. He argues from a false premise, and frankly most of us have better things to do than unpick all the nonsense resulting.

The evidence of history deriving from the sober and sensible engineers responsible for keeping the railway's equipment running is clear enough, the Thompson pacific designs were inferior in service compared to the previous and following Doncaster pacific designs. All of these pacifics were based on the same family of major component designs developed at Doncaster; the change that Thompson introduced being the altered engine and frame layout to place the outside cylinders behind the bogie.

The resulting frame weakness was with the locos so constructed for the rest of their working life, and made them less reliable and imposed a greater maintenance burden compared to the frame layout Thompson had abandoned. All very ironic as Thompson's claims for the necessity of this change was to improve the reliability of the locomotive, compared to the layout Gresley had used. When his successor Peppercorn reintroduced the previously used frame layout, reliability was restored.

It is rare that the evidence is that clear, and you have to be a blind cultist to try and argue past it in my opinion.

Thompson did some very good work, both before he was CME, and then when he had the chair (such positions were not obtained unless there was real ability to support them). Most notably of course the B1, which when tested by BR was found to be first in class against the much lauded Stanier Black 5, and left the Hall well behind. Not only would it do the same work on less coal and water, it was a much cheaper locomotive to construct.

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D605Eagle
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Re: What does the term rebuilt mean

Postby D605Eagle » Sat Aug 11, 2018 5:51 pm

Apparently some people loved Hitler....but there you go :wink: :lol:


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