The LNER Encyclopedia

Whilst RCTS goes into great detail about the re-boilering of D9s and their new cylinders and piston valves, I have not found reference to the frame plating under the smokebox. Any thoughts?

Ay up!

I wouldn't have thought that the frames would need any mods to take PV cylinders, especially with them being inside. The changes would be entirely within the frames. The valve gear might need altering - most slide valves are outside admission, piston valves inside.

I would suggest that a look at photos would establish why I asked the question. There is a change in the profile of the frames above footplate level and evidence of plating beneath the smokebox.

Are you sure that the difference in frame profile wasn't due to the locos being built by different companies?

I believe I now know the answer. When the revised cylinders with piston valves were installed the access panel beneath the smoke box protruded forward of the concave curve of the frames. A panel with a revised shape to disguise this was most likely bolted over the frame. This is why on the photos of re-cylindered engines there is no evidence of bolts holding the cylinder block in place. There are however some six bolts holding the panel in place. A photo of BR No 62307 on page 79 of Yeadon's Volume 29 shows this panel removed and apparently lying on the footplate, the original shape of framing is exposed as are also the bolts attaching the cylinder block. It must be appreciated that at the time the engines were re-cylindered Arc Welding was not in general use. In later years, as with some D16s, a piece of additional framing could have been welded in place. Having given my conclusions, on page 78, BR No 62313 does not have this feature. It is possible that in this instance the frames have been welded or new frames, or part frames, have been used. That said it still has the revised profile.

Aha!

This also suggests to me that, concurrent with the fitting of PV cylinders, there was a superheater installed, hence the extended smokebox to make room for the header. Indeed, a perusal of our D9 Page will confirm this.

Again in Yeadon's there is a photo of GCR No 1026 as originally re-built in December 1909, (first with large boiler, original length firebox and re-cylindered). This photo shows the modifications I have highlighted. According to RCTS the first application of superheated boiler was No 1021 in April 1913. Without the appropriate drawings it is difficult to have a view on whether or not the smoke box was further extended when a superheater was installed. As the quoted dimensions of the D9 and A5 boilers are identical it is possible that their respective smoke boxes were of similar lengths; but I wouldn't bet on it.

The extra plating applied to the frames on 11D locos is something that most folks ( including kit manufacturers) have yet to notice.
No 1026 was indeed the first to receive the larger boiler/ small firebox combination in 1909...but it was not superheated and retained a shorter smokebox , as on the 11C, so leaving the frames unaltered. I should add that 1026 was given a superheated boiler in Oct 1914.
No 1021 then was the first to get the superheated version complete with lengthened smokebox, in order to accommodate the headers. Not only was this larger but also a good deal heavier than the previous set up. In my opinion ( for whatever that may be worth !) these plates were added as a means of strengthening the frames in this area against any perceived extra stress's.
Robinson wasn't the sort of engineer to strap lumps of plate steel to frames for cosmetic reasons, just look at No18, the sole 9K (C13)to be superheated in GC days...the frames had pieces carefully welded in to accommodate the longer smokebox.

I have been looking again at this issue and others may find the following helpful.

11B originally built with 18.5 x 26 inch cylinders with slide valves, 4ft inch diameter boiler and 21sq ft grate.

First attempt at improvement (engines 110 and 104), increased 5ft diameter boiler coupled with 26 sq ft grate but retaining slide valves. From photographic evidence the smokebox appears of a similar length to the original.

Second attempt (engine 1026), 5ft diameter boiler coupled with the original 21sq ft grate, with new cylinder block that replaced the slide valves with piston valves.

Improvement on second attempt with improved ? cylinder block and the super heated type boiler as used on class 9N (A5).

Final move gradual replacement of 24 element superheater with 22 element superheater.

RCTS states that piston valve 11Ds (D9s), had the same pattern of cylinders as 11Es (D10s). A rough calculation would indicate that the valves spindles of the new cylinders protruded some 1ft 3inches forward of the older slide valve cylinders; this presumably would have necessitated a revision to the cover below the smokebox. It is clear that the 11D had a longer smokebox than the 11B (I speculate of a similar length to the 11E and 9N), but whether 1026 was similarly treated I have no idea. RCTS is vague on this point as apparently at the time of publication no detailed drawings of 1026 had been identified.

On page 79 of Yeadon's volume 29 there is a photo of ex 1021 being serviced and on pages 10,11 and 12 of "Steam Memories Darlington Scrapyard 1948-1964" are photos of 62301 and 62312 (ex 1014 and 1027), being dismantled. From this, admittedly small sample I concluded that the original frames were modified/extended to cater for the valve spindles and extended smokebox. Indeed I think that there is a trace of the original framing shape on 62301 and 62312.

As the bolts associated with the cylinders and possibly the smokebox are on the original framing I am not convinced that the covers, held in place by what appears to be six bolts, were intended to reinforce the frames. I would have thought that frame reinforcements would have been bolted flush with the original frames. Other than to cover the grotesque array of rivets and reinforcing strip below the smokebox I am at a loss as to why the covers were required. Having said that smaller covers possibly covering those cylinder block bolts above the footplate are apparent on other classes including the C4 and O4.

I have studied the NRM list but cannot find a suitable detailed drawing for a 11D listed. There does remain the possibility that the GCR Society could assist. Whilst any factual information would be welcome, for the purpose of any 4mm model I am content to settle for photographic evidence and an amalgam of drawings of the 11B, 9N9A5) and 11E (D10).

Pebbles wrote:As the bolts associated with the cylinders and possibly the smokebox are on the original framing I am not convinced that the covers, held in place by what appears to be six bolts, were intended to reinforce the frames. I would have thought that frame reinforcements would have been bolted flush with the original frames. Other than to cover the grotesque array of rivets and reinforcing strip below the smokebox I am at a loss as to why the covers were required. Having said that smaller covers possibly covering those cylinder block bolts above the footplate are apparent on other classes including the C4 and O4.

This piece is a doubling plate riveted to the outside of the frames. You can see the rear edge of it in the photo on page 58 of Johnson Vol 1. Its purpose was to support the front of the new longer smokebox and to close off the original cylinder bolt holes. That the bolts for the piston valve cylinders did not match up with those on the earlier cylinder blocks. Also it is more than likely that putting a longer smokebox on the original frames would have made the front end of these locos look faintly ridiculous would not have escaped the notice of the staff in the Gorton drawing office.

I have studied the NRM list but cannot find a suitable detailed drawing for a 11D listed. There does remain the possibility that the GCR Society could assist. Whilst any factual information would be welcome, for the purpose of any 4mm model I am content to settle for photographic evidence and an amalgam of drawings of the 11B, 9N9A5) and 11E (D10).

The drawings needed for the rebuild were entered in to the Gorton drawings register, which is in the NRM. Whether any have survived is a different question.