Favourite/best Preservation Moment

1985. Alton. Having burnt the candle at both ends laying track for 6 months we were all knackered. It was the day before Major Olver's inspection of the line from Medstead prior to opening. We ran a rehearsal of his inspection train (34016 + 5 Mk1's) from Alresford to Alton in the late afternoon. I was on the loco, as was Ken Woodroofe, the GM. After arrival at Alton Ken and I went over to the edge of the bank while the loco ran round. I said to Ken 'I enjoyed that, but don't ask me to do it again!'. It was a good feeling to have finally got there.
Pat

 

I was reading about this phenomenon earlier in the week, getting a higher reading in the gauge glass with the regulator open. Do we know what actually causes it? If the regulator is open does that mean it physically draws more water over the firebox crown or just that it shows more water in the glass?

The example I read had a driver (think it was Donald Beale) keeping the regulator open longer on a station approach as they were so short on water - but if it’s just showing a false reading I don’t know what the advantage would be...


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No, it isn't a false reading but a false level. The steam flowing through the regulator valve, which is generally as high in the boiler as you can get it, or with a smokebox regulator the inlet grid is as high as you can get it, draws the water behind it so the water's surface is a bit higher with the regulator open. Horwich Crabs were notorious for this false high level, and many a driver closed the regulator on topping a summit. The combination of the water surging to the smokebox end due to gravity and the drop of entrained water would cause the level to disappear somewhere below the bottom nut, and the driver's receiving a Form 1 asking him to explain why he had 'dropped' the fusible plug.

 

@Steve has explained it in the past. Essentially you have to provide a force to move the loco uphill. However, because the water isn't rigid, the only way to provide that force to the water is through a "head"; in other words the water has to be higher at the back to provide a force to push it forward, which causes a rise in the glass. (The opposite happens when you brake: in order to slow the water down, you need a head higher at the front; that causes the water to drop in the glass).

There is a second effect caused by geometry: if the loco was stationary on a gradient, the water level would be flat in absolute terms, which gives an apparent rise at the low end of the gradient, i.e. over the firebox if the loco is facing up the hill.

There is also probably an effect where the water is drawn up under the regulator, but since the regulator is in the middle of the boiler on an old engine, any rise from that means is under the dome, not over the smokebox - possibly different on a loco with the steam inlet over the firebox, as on GWR locos.

If you now imagine a loco working smokebox first up a gradient and then going onto a gradient downhill: When it is going uphill, the geometric rise and the force-based rise add up, so you get a significant rise in water level over the back of the firebox, which shows as the water level rising in the glass. As you go over the crest, the forces reverse and also the geometric effect reverses and goes the other way. The net effect is a very large net change in water level, made worse if the driver also brakes heavily.

For loco working backwards up a gradient, the geometric and force-based rise work in opposition, so the water level seen in the glass is closer to what the "real" level would be (i.e. with the loco stationary on the level). So you get a fairly small change of level when you change from working uphill to braking downhill.

The relationship between what you see and the "real" level is one of the things you have to get your head round. The "false" level is though a true level in the sense that if you see the water at the top of the glass when working forwards up a hill, then it does mean at that moment you do genuinely have lots of water over the crown. The point you have to consider is how much it will fall when the driver shuts off and / or the gradient changes. The reason for wanting the water full in the glass as you approach the summit at Imberhorne is because you know even there, it will fall down towards the bottom nut over the top, before recovering (ideally) to about half glass when you get to the level.

It was interesting when we had 178 facing north and 323 facing south, because you needed to fire them quite differently on account of those changes in water level with gradient. You couldn't allow the water to ever be in sight on 178 when the regulator was open heading north, but could quite comfortably take 323 up with the water at or just above half glass, knowing that the gradient changes worked for you rather than against you. Coming south it was the opposite story, and 178 was a doddle to fire whereas 323 could be a real handful.

Tom

 

Awareness of water level is just about the key thing to learn on the the footplate IMHO.
A fine degree of understanding of not only where your water is but where it is going to be gives a fireman much more freedom in how they manage the the fire.
From a fireman’s POV, drivers handle engines differently and it is part of the skill in adapting to all the variables, driver, engine type and condition, boiler water and coal quality and so on.

As a driver you are making decisions about the operating the controls taking into account all these variables and more. For example you are often ‘braking to the water level’. By which I mean when travelling chimney first you brake gently enough so the tide doesn’t go all the way out.

Tom mentions the summit at Imberhorne, if you go over it at line speed, there is not much room to get the train smoothly down to the 10mph on the viaduct. Especially as the fireman will have run the boiler level down to avoid blowing off at East Grinstead.

I could add a lot more. If only I had the time...

All this is what makes steam engines such interesting things.

 

Really clarifies that - thanks both of you!


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Back to the thread, these are personal experiences. and all the richer for it.
Sometimes it's the routine things like the Mets and 4 wheelers being pulled out the SP shed by one of Wainright's finest.
Or a day where you run boringly to the timetable seeing your passengers enjoy their day with you/
Oh I was lucky enough to be involved in Wonder Woman. Best thing I'll ever do with a steam engine.

 

Sorry to disagree, Tom, but the position of the steam inlet doesn't come into it. The Horwich Crabs mentioned had a conventional dome and regulator valve in the middle of the boiler and, as said, were rather notorious for this phenomenon. Strangely, the Stanier version, which I know well, suffered far less although the steam inlet was at the front of the firebox, but it was still apparent. I believe one of the SVR's GWR engines, probably the small Prairie, had quite a reputation for doing this too.

 

I think I can buy the explanation of steam flow dragging the water towards the dome, and the effect of a gradient (up or down) is obvious. But I don't follow this

When you're braking, that forces the water towards the front of the boiler, the deceleration being equivalent (thank you Einstein) to a gravitational force towards the front. Likewise when you're accelerating, that forces the water towards the back. But if you're going uphill at a constant speed, surely the only effect is that of the gradient.

(Apologies for continuing the thread drift, but it is an interesting subject.)

 

Sorry, I'm going to disagree with you to some extent. A while ago I did an experiment. I took a loco not in steam and with water in the boiler and being hauled by a diesel. We stopped on a gradient and I marked the steady boiler water level with some tape. We then set off uphill with the diesel hauling us. The water level rose in the glass by about an inch. No open regulator as the loco was not in steam. There are some videos by Spirax Sarco showing what happens in an industrial boiler under different steaming rates. and in particular are relevant but the whole series is worth watching. The water level does rise at the point of take-off but not elsewhere in the boiler and, as is said, high demand does not show as a change in level in the gauge glass.
With regard to the Crabs, they had a parallel boiler so the front tubeplate is presenting a larger surface area than the taper boiler version. That will produce a greater variation of water level when the regulator is shut and the driving force disappears. GWR locos have their steam take off at the back of the firebox and turning an injector on will cause a rise in water level in the gauge glass, which is not simply because the boiler is being filled.
Boiler water level is a complex subject. Water in the boiler is also not static and is constantly flowing. For flow to take place there has to be a pressure difference, however slight. One inch of water pressure is only about 0.04 psi.

 

It's because if you are going uphill at a constant speed, you have to provide a force lift the mass of the engine and water against the force of gravity. That essentially means you have to provide an upwards force to each part of the mass, and, because the water isn't rigid, it requires a pressure differential in order to cause it to move upwards in space.

Putting some numbers on it: Imagine a loco moving at a constant speed up a 1 in 100 gradient. That means you need to impart a force of 0.01g to counteract gravity and keep the water moving vertically upwards at a constant speed. Because the water isn't rigid and the steam acts equally across the whole mass of water, the only way to provide that force is with a head of water, i.e. a lift at the downhill end.

Hypothetically, if the water was a cube of 1m on each side, you need to impart a force of 100N. (1 m^3 = 1,000kg, for which 1g = 10,000N so 0.01g = 100N). That means you need to have a pressure differential of 100N.m^-2 between the back and front of the cube. That requires the water at the back to be about 0.01m (1cm) higher than at the front - i.e. you would get a water level rise of 0.5cm in the glass, and an unmeasured fall of 0.5cm at the front.

If the boiler were 5m long, you have five times as much mass to raise against gravity, so need five times the pressure differential - a rise of about 2.5cm (1 inch) in the glass. If the boiler is actually a cylinder - or tapered ... it all starts getting complicated to calculate. But the principle is the same: you will get a few centimetres rise of water in the glass just to maintain a constant velocity on a gradient, quite apart from the geometric effect. Steeper gradients require more force and therefore a bigger rise.

I've never had the opportunity to verify it, but I believe that if you towed a "dead" loco up a gradient at a constant speed, the water would rise in the glass more than would be required just by geometry: doing that would show that although the effect is often called "regulator lift", it isn't due to the lift caused by the local lowering of pressure by the regulator intake, which is a separate effect.

(There was a discussion here: https://www.national-preservation.com/threads/conditions-inside-a-boiler.1006363/)

Tom

 

So many memories and Athelney and John Petley have already mentioned two brilliant days with 35028.

Something a bit "left field", Brienz Rothorn Bahn 2 working on the Snowdon Mountain Railway. Not much good for photography, but well worth going to Llanberis. It didn't go as far up the line as planned due to incompatibility of the loco pinion and the SMR rack, but it was a brilliant occasion and atmosphere.

Cheers, Neil

 

When you are going uphill at a constant speed you have to provide a force to overcome that due to gravity, otherwise you would slow down. This applies to every part of the loco, including the water. You can only apply a force to water to keep it moving by means of a differential pressure head.
Edit: Tom has explained in far more detail than my two lines.

 

26th April 2009, about 5pm.

Sat on the tender of 3440 as the Steel, Steam & Stars II Cavalcade arrived into Carrog with a round of applause as the evening sun was setting on what had been one amazing 9-day event.

With Will Naylor on lead 9017, and Quentin McGuiness on 5526 in front, 3440 was third loco of the cavalcade and as we subsequently stood on the platform neither of us said much but just took in the atmosphere of a job well done; with smiling faces of visitors and volunteers beaming allover Carrog whilst waiting for 6100 to bring the return set into Platform 1.

It was right Will/Q we’re on the lead 2x locos; they were the ones who had an idea that they made happen. However the faith they showed in presenting a 21 year old with the task of writing 10x days worth of timetables and diagrams - and to tell far more experienced people that that was how it was - was beyond surreal and has never been forgotten. I learnt a lot in the 2 years of planning for SSS2, many lessons I’ve taken with me to my subsequent involvement in the CVR’s events team.

There are so many other memories I have, both from that one gala and the rest of 16 years volunteering within preservation. But for the general feeling of a job well done, the silent acknowledgment amongst the three of us that we’d just run this huge event despite the naysayers; and that hardly anyone on the platform realised this - it’ll just never be beaten nor repeated. Seeing so many people happy from your efforts gives huge rewards to all involved in such events, and makes it all worthwhile.

 

I think you're only saying that the boiler is tilted at 1 in 100 so the water surface is inclined at 1 in 100 relative to how it would be on level track; which is what I meant by the effect of a gradient being obvious. But we should either shelve this subject or take it off line, as a distraction from what this thread is supposed to be about.

 

I was on one of those trips when 6998 Burton Agnes Hall replaced Sir Lamiell, as she on our wheel drop at Didcot at the time, due to running a hot box near Oxford. And Burton Agnes was a short notice replacement

 

Moved here: https://www.national-preservation.com/threads/conditions-inside-a-boiler.1006363/#post-2562683

Tom

 

finest moment for me was one evening at Fleet I forget the date, but it was the first official run with steam over 3rd rail on the southern, Waiting in anticipation, Chatting to some kids who asked why everyone was out there, one said oh it will be running slowly then, A few minutes later a whistle, and 75069 flew out of the darkness, at what felt like line speed , leaving steam and smoke in its wake , Second was one sunday evening, At Weybridge Pitch black, then 30053 bustles through the station, with a couple of Mk 1's followed very closely by 35028 with the rest of the coaching formation , on the fast, again, its the whole surreal part of it, an almost deserted station dark, then out of nowhere, a shrill whistle, and in an cloud of smoke and steam this old relic trundles past then as the smoke clears, along comes the express, that lovely middle c whistle, as Clan line thunders through on the old racing stretch.

 

Without doubt my best moment was being in the stand at the Shildon 150 cavalcade. My father took me and we had a weekend 'up north'. Seeing the likes of Hardwick, Midland compound and Shannon steam past.

The last item was the HST prototype, 45 years later and there are still some about, we have a couple of power cars at work in warm storage.

The real change is the way the world operates now, BR let locos steam to Shildon with a minimum of paperwork/fuss. If you were to try this today the road haulier would be the only winners.

To be 13 again!

 

I have struggled to single out one moment to nominate. I have been fortunate to have had so many enjoyable times in preservation over the past 60 years, the first being on the Bluebell in 1960. I have had to set aside many, including the following:
Travelling behind 45231 on the S&C - she was stopped twice by signals on the climb from Settle to Blea Moor, started cleanly each time and was making a wonderful noise from Ribblehead to the tunnel.
Duke of Gloucester crackling up to Whiteball - seen from the lineside.
Double headed Black 5s passing the place where my late Father's ashes are scattered, on his Birthday.
On the footplate with my eldest Son driving on the Middleton Railway.

But the one I have settled on cannot be repeated. It is my late Father on the driver for a fiver experience at the Middleton Railway Railway with my eldest son supervising. It was only the second time he had driven a standard gauge steam loco.