Locomotive Performance and Tractive Effort Discussion

Did I say that? The photo is from Swindon! It would seem at least that the LNER had a few more things to learn from Churchward about standardisation!

 

I read somewhere that Swindon regarded the smokebox as another ring of the barrel. God knows why, but that might explain it.

 

And yet, here is one at Doncaster:



Source: https://www.alamy.com/stock-photo-t...ce23aefb6e5060565d40ab3aceb7d838&searchtype=0

 

Yes, and as you have indicated, the odds are that the smokebox would have had to be removed anyway to fit on another locomotive with a different arrangement. Standardisation has so many advantages!

 

Here’s one for @LMS2968 - Derby, 1926



Source: https://www.fineartstorehouse.com/h...opical-press-agency/boiler-shop-18361765.html

The original discussion was about blast pipes; and even if you remove boiler and smokebox together, the blast pipe stays behind.

I seem to recall there is various discussion in Holcroft in which poor steaming was investigated and the cause coming down to a misalignment of blast pipe and chimney, which could happen if the boiler is removed and then replaced an inch or two out.

Tom

 

A whole Inch ? or two ? gulp.

 

Possibly less, I’m away from the reference. But I recall it came up several times in Holcroft in relation to locos that steamed poorly, especially if one loco from a class was worse than the others.

Tom

 

Which raises a point: the smokebox is bolted rigidly to the saddle and the boiler fitted to the rear of the smokebox while the firebox end is free to slide longitudinally, so if the smokebox is returned to the same engine, it all has to line up, irrespective of what boiler is fitted.

 

Thanks Tom, suppose with the fit being slightly out the wrong way on all the possible interfaces: boiler to support, boiler to smokebox, smokebox to chimney, Blastpipe to cylinder block (esp if not true/ vertical), cylinder block to chassis. then an inch is possible...

 

That is probably the reason why loco overhauls took a lot longer at Swindon compared with other loco works.

 

Why? Because they didn't remove the smokebox, unless it was necessary? That statement doesn't make much sense. Of course it could have taken longer for other reasons. How many miles did a GWR loco run before overhaul, compared to other companies?

 

Crewe, Derby etc would have had an overhauled spare boiler to use, Swindon would have to overhaul the boiler and re-use it. If you look at overhaul dates on loco record cards, this is quite obvious. At Crewe it took longer to repaint the loco than to overhaul it.

 

You are implying that the same boiler would have to go back on the same locomotive? With standardisation, a boiler could go back on any member of the same class, or even a different class. So according to you, Swindon didn't have any spare boilers? I'm not sure you know what you're talking about! Even the 47xx had one spare boiler (which required careful planning).

 

As an example, 4150's overhaul record at Swindon shows it had 5 different boilers during its working life. The current boiler, 5895, began life on a different 5101 class but was also used on three other 6100 class locos.

 

I guess it's also important to consider that the fit of the smokebox to the saddle should be as good as possible to avoid any air leaks that could reduce the smokebox vacuum.

 

Did the differences of the four types relate to the draughting, or were they just differences in the way they were fitted to the locomotive?

 

Draughting, size of blastpipe nozzles and yes, some slight differences in fitting (bearing in mind you have some classes with seriously less space in which to fit the equipment than others). All notionally the same thing, all in reality slightly differing variations.

 

Until fairly recently I always thought that the 61xx boilers were different because of the higher pressure - nickel steel I read somewhere. But it appears that they were the same as those fitted to the 41s and 51's, which does beg the question why these didn't operate at 225psig. Horses for courses, I suppose.

 

If there is any documentation relating to how the various dimensions of the components of the Kylchap affect the draughting, there would be a lot of interest from enthusiasts. Porta produced a detailled paper explaining how to design a Lempor, but there is precious little information available relating to the Kylchap.

 

Probably why there is still the occasional Lempor, not Kyllchap , retrofit or new build.