6619

There's no denying its snug and it takes a bit of thought to get out (the first time I did it I ended up dropping back down with one leg either side of one of the brake cross-beams - you only do that once!), but it works for me.

Of course, as with any GWR engine there are disadvantages to being reasonably tall; the inability to finish a day without getting concussion from smacking your head on the cab when leaning out being one of them!

 

Don't forget that the 56xx was designed for the Welsh Valleys where the train crews were, historically, smaller than their English counterparts.

 

It's here! 6619 was unloaded on to K&ESR metals this morning, the same lorry took No 65 off to the Yorkshire Dales Railway. 6619 is facing Robertsbridge to make it more appealing to photographers and to provide the opportunity to have a loco facing chimney first out of Tenterden for Pullman and other prestige trains.

 

My experience of GWR locos would seem to prove the rumour that all GWR drivers weighed under 8 stone, were about 5 feet tall and had arms so long that they had scabs where their knuckles dragged on the ground.

 

Do you get a lot of them in Kent then?

 

From observation, I'd say 'yes'.:behindsofa:

 

Quite a few, plus I do have a car and there are roads that lead out of Kent and to other preserved railways.

 

Great news! I hope to see it next time we're back in Sussex. It's an interesting idea to have the loco facing Robertsbridge. Although this means bunker first up Tenterden Bank, it's interesting that the Bluebell prefer to operate their 0-6-2T (Birch Grove) bunker first in the "uphill" direction too. As you say, it opens up some interesting photo opportunities.

 

In the days before the Pickering turntable was installed, when most NYMR engines pointed up the bank, 6619 was unusual as the only one which faced Grosmont. History repeats itself.

 

It's a lot easier for the Fireman to accurately manage the boiler water level on the banks when running tender or bunker first. Running chimney first, "regulator lift" plus the effect of the gradient means you get an artificially high reading in the gauge glasses. While it's obviously possible to compensate for this, it's an inexact science. With a loco working hard chimney-first on a 1-in-75 hill the basic rule of thumb is, if you can see the water level, it's time to put the injector on. That's ok on most engines but prior to being fitted with a blowdown there was a very fine line between running with too little water and too much on the E4, which always had a tendency to prime.

Bunker first there's no regulator lift and the gradient is in your favour in terms of water level above the crown - when you get back on the level it'll go up, not down.

However I suspect the reason it's that way round actually has more to do with filming work than any deliberate operational policy. Several Bluebell locos have been turned over the years in order to please film companies. Without a turntable this is a matter of winching the loco onto a lorry, spinning it round in the top car park and then unloading it again!

 

SE&CR, sorry to disagree but there is always an artificial raising of the water level whenever the regulator is open, the direction of travel or gradient will have no effect on this. However, perhaps this is less noticable when the level is lower in the glass if you are running backwards up a gradient. What you have to watch out for when running tender/bunker first up a gradient is water carryover if the steam collection point is well towards the front of the boiler due to the level being higher towards the front. We have this problem with several of the locos at Foxfield when running cab first up some of our gradients.

 

Well you can disagree all you like but I volunteer on three railways (Bluebell, CVR/MCR and Bo'ness), and have never noticed any particular regulator lift when running tender or bunker first on the flat. I agree that doesn't automatically make much sense, but it's the reality. The whys and wherefores would make an interesting debate in their own right. Likewise if you wish to demonstrate on a Foxfield machine I'd be interested - as I say it's not something I've ever seen.

The point you are making about priming is exactly the point I've already made about the E4, except applied the other way round. As the take-off for the regulator is generally (though not always) towards the middle of the boiler, the fluctuations in boiler water level are always going to be less here than they are at either end. So it all boils down to how easy it is for the Fireman to judge the level. Chimney-first you have both regulator lift AND the gradient against you, so you're running with the water level out of sight for much of the time. Fine on engines like BR standards but a problem on some older round-topped firebox locos which are prone to priming. How far above the top of the glass is going to be all right when you shut off, and how much will cause it to prime, and how the hell are you supposed to gauge the difference when you can't see it anyway?

Running bunker first is easier because the regulator lift *seems* to be minimal and the gradient acts in your favour, as the water level over the crown will rise when the grade levels out. You can run with half a glass safe in the knowledge that when the regulator is shut it won't all disappear. Half a glass at the cab end shouldn't be more than about 3/4 at the dome surely, even on 1-in-14? Conversely if you're assuming that there's more regulator lift going backwards than there actually is, it might explain why you're having priming issues? Just a thought....

 

That's true enough, though I'd hope that on the flat there wouldn't be the same need to mortgage the water against the steam pressure!!

 

Here's a video that might interest regarding water responding to different demands to steam in a boiler. Steam Boilers - The Inside Information (Part 2 of 2) - YouTube

And that is all happening in a stationary boiler!

 

The water level used to rise with load on the 950 psi boilers that I worked with while at sea. We didn't go up or down hill much!

 

Opening the regulator lifts the overall water level due to steam bubbles forming, and also shifts the water towards the trailing end due to acceleration. Going forwards those effects add at the cab end, while going backwards they oppose each other, giving a smaller net effect (possibly no noticeable effect if they happen to be nearly equal; whether this is the case will depend on the loco and load).

The acceleration part is what we often think of as the gradient effect, but as gravity and acceleration are physically equivalent, it actually doesn't matter whether you're opening the regulator to climb a hill or to go faster on the flat; in theory, if you shut the regulator the water will drop to the same level whatever gradient you're on. However, in practice trying to get the "true" level this way doesn't work particularly well, as on a gradient steep enough for this to be a big issue in the first place, the water level will bounce severely from the sudden change in acceleration, and you can't leave it shut long enough for this to stop without rolling backwards.

 

Well, I'm going to disagree with you and agree with SECR. When you are running smokebox first, the water rises in the glass and when running tender first, it will be lower in the glass, as compared with when stationary. The water has a natural tendency to resist motion so will always be higher at the far end when the loco is in motion. When you shut the regulator, you effectively remove the driving force so the water will tend to level out, causing the fall or rise in the glass, depending on which way you are going. The water is lifted by the regulator being open but this is in the area of the steam offtake (usually the dome). Other offtakes, such as the safety valves operating, will cause the water level to rise locally to that offtake. Turn an injector on on 6619 and the water level will rise by anything up to 3/4" and drop back when it is turned off because the steam offtake for the injectors is near the back. When running tender first, you often have to run with the water in the bottom part of the glass to avoid primimg, all part of the knowledge and experience needed by footplate crews and why any form of automatic water level control would be impractical on a locomotive boiler.

 

I've long advocated that it is better to run bunker/tender first uphill in terms of maintaining a safe water level for the reasons that you state. Where a line has both uphill and downhill sections it can negate the argument, though. The Bluebell and Worth Valley are good examples of where it would be a sensible policy.

 

But I bet you pitched and tossed in a storm! More seriously, I suspect that your boilers were not relatively long like a steam locomotive and the offtake would be relatively nearer the gauge glasses.
Boiler water levels is a very complex subject with so many variables.