Talk:GWR 5600 Class

Weight?
There seems to be some disagreement about the weight of the 5600/6600 classes. The figures I have put in ==Dimensions== come from the Ian Allan ABC of British Railways Locomotives. 82.21.65.109 08:48, 25 March 2007 (UTC)
 * Possibly, 62 tons is the weight without fuel and water and 68/69 tons is the weight with full tanks. 82.21.65.109 08:53, 25 March 2007 (UTC)


 * Following the addition of the latest reference, the dimensions section is rather confusing now, with two references for five different weights! If you look at this edit, you'll see that I added the fact tags, and the second (referenced) weights, back in January this year, so I'm probably best placed to help resolve this.


 * Now, I think the Observer's book should be a reliable-enough source, especially as it is a revised edition, but in this case it is possible that there is a printer's typo. That book states 62 tons 18 cwt rather than 68 tons 12 cwt, so it is clearly possible that the '2' and '8' were transposed in the typesetting (difficult to spot). This hypothesis is supported by the new reference and the data previously in the article. (As I'm at work, I don't have the book to hand, but I find it hard to believe that I would add all the extra text and fact tags without reading the figures more than once, so I don't think it's a transcription error on my part.)


 * For the 6600 weights, the Observer's book actually states "15 cwt more than 5600". Having looked up how many hundredweight are in a ton (showing my lack of age!) this would indeed make the 6600 weigh 69 tons 7 cwt. Hence, between the two refs it is possible to confirm both the original weights quoted in the article (although I think the cites ought to note the wording used in the Observer's book for the 6600, and its discrepancy over the 5600 figures).


 * I found a number of webpages that mention weights, but as they are all 'wrong' to some degree, none (except perhaps the last) is of any particular use here, especially since there is clearly a need for a definitive answer within WP:
 * Swanage Railway, 6695, loco ex-Barry, very old PDF! Uses 56xx figure for 66xx loco
 * Spa Valley Railway, same loco, some years later! Weight rounded to 68tons.
 * Gloucester Warwickshire Railway, uses Observer's book figure for 56xx
 * RailInfo, supports our 'referenced' figures, not sure reliable though
 * Steam Index, list of possible paper references


 * -- EdJogg (talk) 09:53, 10 August 2010 (UTC)
 * First off, the Observer's book was originally prepared by E.F. Carter, who didn't take 100% care over accuracy. The 1955 (ie first) ed. has (p.236):
 * Weight: 62 tons 18 cwt.
 * Water Capacity: 1,900 gals.
 * Coal Capacity: 3 tons 15 cwt.
 * Number Series: (“56xx”): 5600 to 5699. (66xx”): 6600 to 6699.
 * Historical Notes: ... The “66xx” variant was introduced in 1927, and weighed 15 cwt. more than the “56xx”-class engines ...
 * He does not state what differences caused this change in weight.
 * The second and subsequent editions got the attention of H.C. Casserley, but he didn't amend every entry; and although he does make small changes to the page on the 56xx/66xx classes, none of the information under discussion is significantly altered right down to the "Fifth Revised edition" of 1966 (p. 47), which compared to the first has just one of these lines changed (a typo plus three additional words):
 * Number Series: (“56xx”): 5600 to 5699. (“66xx”): 6600 to 6699. Some now scrapped.
 * It is conventional in Britain to give locomotive weights in long tons and long hundredweight (2240 lb and 112 lb respectively), as opposed to the short ton and cwt (2000 lb and 100 lb) used in the USA. It's also conventional (in Britain at least) to give locomotive weights in working order, that is, with full bunkers, tanks and sandboxes; with boiler filled to 3/4 glass; fire laid; and moving parts lubricated. The difference between empty/full weights is significant. If we consider only the bunker and tanks, these hold 3 t 15 c coal and 1900 gall water. Since 1 imp. gall. of water weighs 10 lb, this makes the weight of the water in the tanks 8 tons 9 cwt 72 lb. Add on the coal, and the empty/full weight difference becomes 12 t 5 c (to the nearest hundredweight) - something like twice the difference between 62 and 68/69 tons. Subtracting from 68 t 12 c gives 56 t 7 c. Official GWR information gives an empty weight some 2 t 15 c less than that, so probably takes into account the water in the boiler as well:
 * This book has several sequences of page numbering. On p. 33 of what claims to be a reprint of the 1928 edition, the 5600 class (no loco numbers given) is shown as weighing 68 t 12 c; on p.56 a lot more detail is given, including full/empty weights:
 * This book has several sequences of page numbering. On p. 33 of what claims to be a reprint of the 1928 edition, the 5600 class (no loco numbers given) is shown as weighing 68 t 12 c; on p.56 a lot more detail is given, including full/empty weights:

! !!Full !!Empty
 * Leading coupled ||18 t 17 c ||14 t 15 c
 * Driving coupled ||18 t 17 c ||14 t 15 c
 * Trailing coupled ||17 t 18 c ||14 t 0 c
 * Trailing radial ||13 t 0 c ||10 t 2 c
 * Total ||68 t 12 c ||53 t 12 c
 * }
 * This book, which originally was an official GWR publication, makes no mention of any variation (weight or otherwise) within the class. The same figures are shown on p. 75 of the 1946 edition bound together with the 1928 edn.
 * The RCTS books are generally considered reliable sources, even outside Wikipedia. The relevant volume of their 14-part series (which I used as a ref source yesterday) gives four axle weights and a total, all of which are in complete agreement with the GWR figures given in the "Full" column above. It makes no mention of any difference between 5600-99 and 6600-99. It does note that nos. 6650-99 (which were built by Armstrong Whitworth - the first 150 being Swindon-built) had shorter safety-valve bonnets compared to the Swindon engines, but this can't have made much more than 1 cwt or so difference to the weight.
 * Ian Allan ABCs from October 1943 to August 1948 show all 200 as 68 t 12 c, without noting any variation; those from August 1950 on show 5600-99 as 68 tons 12 cwt, and 6600-99 ("Introduced 1927: Locos. with detail alterations" as 69 tons 17 cwt. The nature of these "detail alterations" is unstated.
 * These sources support the idea that Carter transposed 68 t 12 c to 62 t 18 c, and that this error went undetected by Casserley. However, I would like to know exactly what changes were incorporated with no. 6600 onwards before accepting that there was a general increase in weight at that point. It should be remembered that individual locos will always show some variation from the official figures, even showing variations within the same batch. -- Red rose64 (talk) 11:52, 10 August 2010 (UTC)
 * }
 * This book, which originally was an official GWR publication, makes no mention of any variation (weight or otherwise) within the class. The same figures are shown on p. 75 of the 1946 edition bound together with the 1928 edn.
 * The RCTS books are generally considered reliable sources, even outside Wikipedia. The relevant volume of their 14-part series (which I used as a ref source yesterday) gives four axle weights and a total, all of which are in complete agreement with the GWR figures given in the "Full" column above. It makes no mention of any difference between 5600-99 and 6600-99. It does note that nos. 6650-99 (which were built by Armstrong Whitworth - the first 150 being Swindon-built) had shorter safety-valve bonnets compared to the Swindon engines, but this can't have made much more than 1 cwt or so difference to the weight.
 * Ian Allan ABCs from October 1943 to August 1948 show all 200 as 68 t 12 c, without noting any variation; those from August 1950 on show 5600-99 as 68 tons 12 cwt, and 6600-99 ("Introduced 1927: Locos. with detail alterations" as 69 tons 17 cwt. The nature of these "detail alterations" is unstated.
 * These sources support the idea that Carter transposed 68 t 12 c to 62 t 18 c, and that this error went undetected by Casserley. However, I would like to know exactly what changes were incorporated with no. 6600 onwards before accepting that there was a general increase in weight at that point. It should be remembered that individual locos will always show some variation from the official figures, even showing variations within the same batch. -- Red rose64 (talk) 11:52, 10 August 2010 (UTC)


 * It would seem sensible, therefore, to retain this one weight, with your reference, in the infobox, allowing the section to be deleted.
 * I would still suggest that the error in the Observer's books could be noted in the footnotes, to reduce the liklihood of other editors 'correcting' the data in future. And I'll continue to use them as a reference source, although more warily in future!
 * -- EdJogg (talk) 12:14, 10 August 2010 (UTC)

Weights: crank arrangements
I've found a design modification: It seems that the locos as built had the normal crank arrangement for inside-cylinder locos - that is, the inside cranks for the connecting rods were diametrically opposite the outside crankpins for the coupling rods. This helps with balancing the rotating masses, but "As so often happened with high-powered inside-cylinder engines ... the driving axleboxes wore very rapidly. There were two reasons why this was inevitable. The bearings of the outside-cylinder GWR engines were 10in long. On the 56xx class there was only room for 7in between the wheel and the crank web. Not only were the bearings little more than half the area, but with inside and outside cranks set at 180° the fore-and-aft thrust on the axleboxes is greatly increased. Connecting and coupling rods are pulling in opposite directions, and all the force of this reversal has to be taken by the driving axleboxes, which are well suited to cope with vertical loads, but very ill-adapted to near-horizontal thrusts. In an attempt to reduce this heavy wear, which greatly reduced the mileage run between shoppings and so was very costly, a number of the class were after a time altered to have the Stroudley arrangement of cranks. In this the inside and outside cranks are in phase instead of opposite each other. It reduces the thrust by about half and so lessens wear, but since both cranks, big-end and coupling rod are on the same side, instead of largely balancing out, the balance weights have to be so large that they are difficult to accommodate in small wheels. They add very considerably to an already heavy axle load, and this is made more serious by the fact that this extra weight is unsprung." (the boldface is mine) I am of the opinion that this modification could easily account for a 15 cwt increase in weight. Gibson implies that the modification was post-construction, carried out as engines passed through shops for overhaul. Indeed, if this was a serious problem, there would almost certainly be a standing instruction to modify any engine showing such trouble. But it's difficult to see the problem as confining itself to nos. 6600-99, with 5600-99 being unaffected. It's possible, however, that 6600 onwards were built with the Stroudley crank arrangement, the earlier engines being so altered as necessary; this would account for certain publications showing the two number series with differing weights - they would be "as built" weights, not "as presently running".

Further information might be found in: but I don't have those. -- Red rose64 (talk) 12:06, 11 August 2010 (UTC)
 * Altered crank arrangement described in and the altered balancing (although not the full reason) in . Neither give any altered weights; Haresnape quoting 68t 12c as built. -- Red rose64 (talk) 11:26, 19 August 2010 (UTC)

Teething Troubles
There is a rather partisan description of how this design came about, and particularly of early problems with hot boxes resulting from Swindon tolerances being too tight for twisty South Wales coalfield lines, under the heading "Collett's Folly" in:

http://www.nlsme.co.uk/Newsletters/NLSME-March-2003.pdf http://www.nlsme.co.uk/Newsletters/NLSME-April-2003.pdf http://www.nlsme.co.uk/Newsletters/NLSME-May-2003.pdf

Bill F (talk) 12:14, 5 March 2008 (UTC)