john coffin wrote:Whilst I also read the Green book 2B, I have found part of many conversations that were held between Maurice Boddy and Kenneth Leech
of which I have copies.
Who? -- and when was this interview conducted?
This is one part of many that I have access to.
"Thank you, that clears up that story**. Next question. What do you know about the myth (?) that Gresley handed over the task of designing the “Sandringham” Class 4-6-0 to N.B. Loco. Co. because his staff at Doncaster were beaten.
Gresley did not “hand over the problem” of the East Anglian motive power to the N.B. Loco. Co. I saw his proposed design before ever it was sent to the N.B. Loco. Co., and it was a better looking engine than a Sandringham, because N.B. extended the coupled wheelbase towards the rear and put the smokebox forward a bit – otherwise the Sandringhams were all Gresley."
Sorry , but you will have to do better that a bit of hearsay to show that Gresley actually designed a loco with divided drive that just happens to have had the same physical dimensions as the Royal Scots.
And it really doesn't matter how a loco looked, if the engineering didn't work then there was no point in building it.
Neither the Scots nor B17's were very successful straight out of the factory, the 17's particularly were bad steamers initially,
Almost all the problems with the B17s, including the first batch all needing new frame within a year of delivery, stem from Gresley will fully ignoring the design brief he was given.
The fact that you know neither Leech or Boddy shows a lack of proper research into the written histories of Doncaster and its locomotives, but we will put that to one side for the moment.
Your comment about Gresley wilfully ignoring the design brief does not really understand what happened, but more importantly, kind of makes your points wrong in both fact and actuality.
The traffic requirement was for a loco to provide more power than a B12, yet work the same routes on the ex GER. Doncaster tried to create such a loco, with 3 cylinders which is what Gresley wanted, but could not do it by putting the drive on the centre axle. All their initial designs were too heavy in terms of axle loads. In addition the distance between the front driver and the bogie meant that all their designs were not accepted by the traffic and Civil Engineers departments. Since NBL were already undertaking work on K3's, as well as previously doing 02's and Pacifics, they had many Doncaster drawings, they were also provided with drawings of the D49 bogie from Darlington.
The original spec had always been 17 tons max axle load, and even NBL, with all their skills could not create a design with such a low axle load. Both their initial designs being over 1 ton more. NBL found it impossible to devise a 3 cylinder loco with the drive from the middle axle. At which point they copied the drive arrangement of the Royal Scot, but most of the external details were LNER products adapted for the job.
There is definitely no written evidence that can link the frame failures to Gresley ignoring the design brief, unless he actually designed it, which according to you he did not. You cannot have it both ways. The design flaws were due to trying to get down to the axle weight, but the locos were never able to meet the original design brief of being available over the whole ax-GER lines.
john coffin wrote:The original spec had always been 17 tons max axle load, and even NBL, with all their skills could not create a design with such a low axle load. Both their initial designs being over 1 ton more. NBL found it impossible to devise a 3 cylinder loco with the drive from the middle axle. At which point they copied the drive arrangement of the Royal Scot, but most of the external details were LNER products adapted for the job.
There is definitely no written evidence that can link the frame failures to Gresley ignoring the design brief, unless he actually designed it, which according to you he did not. You cannot have it both ways. The design flaws were due to trying to get down to the axle weight, but the locos were never able to meet the original design brief of being available over the whole ax-GER lines.
The GE traffic committee was looking for a more powerful version of the B12* and the 17 ton max axle load would have been consistent with a two cylinder loco. By insisting on three cylinders he ensured that the 17 tons was an impossible figure for the max axle load. This decision was the basis for all subsequent problems with the class.
*Which of course they got when Thompson re-boilered the B12s to B12/3.
The Gresley Pacific cylinder arrangement required the middle cylinder to be set back relative to the others in order for the connecting rod to clear the leading coupled axle. Dividing the drive in the B17 allowed the middle cylinder (and the locomotive's CG) to be moved forward, and the bogie carried about 30% of the total weight. This to a degree followed European practice when high power (requiring a large boiler) was wanted in conjunction with low axle-loads: an example was the 60 tonne Prussian S6 4-4-0, whose bogie carried almost 43% of the locomotive's weight in order to achieve a maximum axle-load of under 18 tonnes.
Strange how different people see things from a different perspective.
The GER traffic committee wanted a TE of 25,000. and it is difficult to understand, if it was so easy that all the combined experience of both
Doncaster and NBL did not come up with a two cylinder alternative to match this figure. My research suggests that that did not happen until almost
20 years later, and even then, Thompson was not able to rebuild the B17/B2 to quite get to 25,000TE.
You baldy stated that NBL designed the B17 completely, but they didn't anymore than they completely designed the original Royal Scots which we all know were based on the Maunsell Lord Nelson class, as well as input from Derby drawing office. It cannot be said that any of the 3 types of loco were
originally successful because of various problems, poor steaming and troubles with the lightweight building.
What fascinates me most is why, with all their knowledge NBL were unable to create an alternative design with two cylinders that created 25,000 TE, but in none of their proposals did they even mention it. All the designs they proposed were a long way over the limit. Which suggests that at the time, with the boiler pressures in use, and the various other items that related to that, it was not possible. Gresley did not confirm the order for overweight locos which were not capable of meeting the brief, ie being usable over the whole ex GER route, it was the Loco Committee, of which he was certainly a member, but why did he let it happen if the loco did not meet the brief? Probably because the demand was so important.
Both the Royal Scot and Lord Nelson classes took almost 10 years to be as useful as was intended, and a lot of modifications, and of course the Scots were rebuilt after the war to make them more effective for their role. Whereas the B17's were rebuilt to fit in with Thompson's standardisation process and not as much as the Scots.
Second guessing history is always easy when there is little information available.
Drifting again! The "Green Book" indicates that a scheme was drawn out for a 4-6-0 in the Kings Cross Drawing Office. This was a three cylinder locomotive with cylinders and valve gear similar to the D49s. Now I would envisage that the D49 evolved from the projected, but never built, three cylinder D21 and so were Darlington designs. One of Gresley's apparent tenets was not to drive on the leading axle, but apparently it was envisaged that the three cylinders would be in line and drive the leading axle with equally spaced driving wheels. The top diagram on page 140 of Volume 3 "North Eastern Record" published by HMRS shows such a layout. Admittedly the quoted tractive effort was less than 25,000lbs but this was arrived at with 18inch diameter cylinders and using 80% boiler pressure in the calculation. Increasing cylinder size to 18.5inches and using the normal 85% boiler pressure figure results in a tractive effort of 25,528lbs. The maximum, admittedly calculated, driving axle loading was 18 tons. It would appear that it was not the weight but the length that eventually caused the problem. One issue that seems to be missing is the "hammer blow", effect of a relatively powerful two cylinder locomotive and at the time this must have been a consideration and influenced the decision to opt for three cylinders. Thompson attempted to minimise hammer blow on his B1s by reducing the reciprocating balance but eventually this policy was reviewed.
Interesting conversation. Geoff. Hughes "The Gresley Influence" P62 discusses this proposal with a drawing dated '1935 although it is believed -- earlier' but gives no sources. The Green Books part 10A gives a description and specifications dating at 1936. It was also suggested it was intended for the GC division. Intriguing to think that if it were intended for similar duties as the V2, had it been reworked slightly with 6'2 wheels its nominal tractive effort would have been 33730 lbs - the same as the V2! Pros- bogie front end. Cons- completely new boiler design comp. with the 'modified" standard wide firebox boiler. Some further comments on correspondence- Presumably the reference to Churchward is regarding the "Great Bear"experiment - a "one-off" like the 'Hush-Hush" W1, and the 2 & 4 cyl. 4 4 2 and 4 6 0. The latter were essentially the same engines- unlike the proposed 4 6 0 and 2 6 2. The point about finance though is well made. Particularly interested in John Coffin's comments, but I must say the B17s were not "all-Gresley". Both the Scots and the B 17 had a most un-Gresley divided drive. - and the shortening was surely because of the limits of the GE turntables. Reportedly the Scots were terrific until their cylinders wore (quickly).
