Current and Proposed New-Builds

I suspect it is even less than marginal if the firebox itself is identical. It may allow better water circulation, but that is all. The idea that the volume of water over the firebox affected steaming was one of the causes of the Gettysburg boiler explosion. Here, there was a belief that, if you had less water over the firebox, it boiled faster and therefore produced more steam. This resulted in them purposely running up gradients with a minimum amount of water showing in the glass. See http://www.okthepk.ca/dataCprSiding/articles/201610/month00.htm for the interesting report.

 

Thanks, Steve, I always had doubts on it.

One thing many people don't realise is that when a loco goes over the summit and starts to descend, water flows to the front end, causing the water level over the firebox to fall, and the fall is significant. The longer the boiler, the greater the fall and the greater the chance of uncovering the firebox crown. This is exaggerated by the driver's easing or closing of the regulator. With an open regulator, the steam flow 'lifts' the water level, which drops again when it is next closed, adding the amount of the water level's fall and the risk of a dropped plug. Horwich Crabs were very bad for this, and caught out many an engineman.

 

Thanks for the explanation, though it occurs that with a lower volume of water per 'unit boiler length' at the front end of a taper boiler, any temperature drop off along the length of the tube, as heat transfer takes place, means the slightly depressed temperature of gases towards the tube plate have less of an impact than for paralell boilers. It also makes me wonder whether the Chapelon 'economiser' might not serve a rather useful secondary purpose.

Did Bulleid's use of taper on the underside of the boiler affect the "surge protection" characteristics in any way? .... and I never thought to be applying that term to the boiler of a steam loco!

 

I'd assume it would be much the same, but could be wrong. The reason for the taper being at the bottom was to reduce weight, as the engines were over their designed weight. The bottom face's tapering upwards towards the front reduced the amount of water carried.

 

Most likely under-cylindered, as the NER's S1, S2 & S3 classes of 4-6-0 suffered from this too, having somewhat pedestrian performance.

Richard.

 

Is it really possible to call a loco fitted with 20" diameter cylinders "undershod"? Of classes mentioned, only the S3 (LNER B16), the most modern looking of the lot, had smaller (181/2" dia) cylinders (would that have been a loading gauge consideration?).

The S1 (LNER B14) looked decidedly underboilered to my mind (though a sight more convincing than the 4'-9" dia boilers of the earlier S (LNER B13)), but I note that the S2 & S3 shared a 5'-6" boiler diameter, though the S3 (the last survivors of the ex-NER 4-6-0 stud by some years) had substantially greater heating surface and a whole extra 5psi by way of boiler pressure (ambitious!).

Looking at the numbers laid out in the LNER Encylopedia, I wonder whether likely reasons for unimpressive performance could be more properly explained by other design shortcomings connected with the steam circuit and draughting arrangements?

 

Where do I sign up?

 

How about a New Build of one of these? A MSWJR 2-4-0 would be unique, interesting and probably not that hard to build provided you could find some drawings. Obviously, building it as withdrawn in 1952 would have the advantage that the Tender and bolier (Which I presume is a standard GWR type, not sure of the number.) would be a known quantity and it might be easier to find some drawings.

 

Didn't the Swindon & Cricklade announce a plan to build one of those a few years ago?

 

Its a standard 11 boiler, not sure there are any of those left, but the 64xx boiler was a modernised version. There don't seem to be a lot of drawings at the NRM according to the list, one of the slide valves and one about the adaptions for the Std 11 boiler. Photos suggest they kept their original tenders. I suppose the thing that occurs to me is that they were very small and light low powered engines. Would they actually be good for very much?

 

http://www.swindonsotherrailway.co.uk/alice.html

What was that other loco that someone was going to build for the Olympics??

 

You could well be right, I need to re-consult my copy of "The LNER 4-6-0 Classes" by Clay & Cliffe, and "LNER 4-6-0s at Work" by G. Hughes... When I can actually get to them!

Richard.

 

Is it just me, or does the second photo look as though the loco is wearing a monocle?

 

It'd be interesting to work out what put the NER 4-6-0's into (in Southern terms I'm familiar with - sorry) the F13 rather than the N15 category.... if indeed they all justified a bad rep in the first place.

The Raven S3 (LNER B16) looks to be a workmanlike job and given they made it into the 1960's, they can't have been all that bad.

When it comes to newbuild candidates, obviously if some looney wants to throw their own cash at the worst turkey in British locomotive history, that's between them and their psychiatrist, but my own view is that there's a line to be drawn between a small-ish ornamental vintage recreation, capable of hauling a couple of suitable period carriages for demonstration and filming/photo-op purposes (or even for frontline use on 'known quiet days') and something like a stonking great mainline 4-6-0 which, as it'd take up a fair bit of shed space, really needs to be a useful addition to a line's operating department .... but that's just me being me!

(I'd best point out I consider that, between the extremes of ornaments and big chuffers, projects such as the F5, G5 and 3MT will fill some important gaps in the ranks as well as providing some extremely useful archetypical branch line locos.)

 

It was slightly more subtle than that. As built, the first five had a parallel ring adjacent to the firebox, and the front ring then tapered (on the bottom only) to the smoke box. After the first locos came in overweight, the design changed to the first ring tapered (bottom only) leading to a second, smaller, parallel ring. The net effect was to reduce weight (amount of steel and volume of water) while leaving all salient dimensions (heating surface, tube proportions) unchanged.

The later design (tapered on the underside adjacent to the firebox; parallel adjacent to the smoke box) is obvious when looking at Ellerman Lines.

http://www.ssplprints.com/image/87327/ellerman-lines-steam-locomotive-no-35029

Tom

 

No, it was for a replica of one of 2 2-6-0s purchased by the MSWJR for the growth in goods traffic. Built mainly for export, 2 of these small-wheeled "Galloping Alices" still survive in Australia I believe. One survived long enough to be taken into GWR ownership. The Swindon & Cricklade Group built a very nice model, but that's about as far as it got. They just don't have the money.

 

http://www.australiansteam.com/2510.htm

 

I spent 10 long years working on 2510's restoration.

Here's a shot of the other one, 2535, taken in happier times.

 

I still find this puzzling. Why not have the diameter at the front as it is and keep that same diameter all the way back? What is the advantage of a greater depth of water below all the tubes at the back?

 

Perhaps something to do with the application of thermic syphons on the Bulleid pacifics? I'm sure one of our number will be able to shed light on the matter. This image is from carlswatson.com :