Bluebell Motive Power

Just like all the ill informed anti GWR brainwashing that goes on here!

 

What the Swindon lot don't get is that they were just one of this country's railways. To hear them go on you would think they were the only one (a bit like the Union Pacific guys over the pond).
Just accept that most of us like other railways, and the more the GWR fan club go on, the more we'll rip the p**s.
Pat

 

What a rediculous comment, properly maintained trial cocks are perfectly satisfactory, easily usable and leave you in no doubt where the water level is! They are even still used on industrial boilers today.

In terms of safety and gauge glasses then, how many boiler explosions occurred on the GWR due to low water in comparison to the other regions??

 

I think most do, but get tired of all the mis information that the other railway fans pedal. Theres some serious p**s taking to be had about the other railways too.

 

Yes, thats lead to several boiler explosions on locos with 2 gauges...

 

Wow - You're taking the bait well today. It doesn't take much to rattle your GWR cage. Like it or not, "p**s taking" as you call it is much more fun when you get a predictable GW reaction like yours

Sorry, just had to say it

Peter

 

So are you saying that from choice, it is no more difficult to get an instantaneous reading of water level from a pair of try cocks than it is from a gauge glass? I can see the water level in a gauge glass at a glance; I can’t do that with try cocks. (And even using them doesn’t tell me the level, only upper and lower limits on the level).

Tom

 

No, I didn't say that at all, what I said was that your comment about trial cocks might as well not exist was rediculous.

 

Throwing the bait back gets an equally quick reaction from the non GWR brigade. Well done you.

 

Peter

 

I had a quick hunt through the accident archive and found three low water incidents in the last 120 years, one on GWR, one on LNER and one on a heritage line, and all involved imported locomotives (2 S160s (single glass) and a Norwegian locomotive). So no data as to whether the GWR arrangement is less or more safe than 2 gauge glasses.

I suppose the other side of the coin is that if you have two gauge glasses you double the chances of a gauge glass failure.

I don't think I found all the incidents there have been though. I believe there was another S160, and I also have a vague memory of a incident where the crew had gauge glasses differing, and assumed wrongly that the one showing a safe level was the one that was reading correctly.

 

There was a firebox collapse on a "Duchess" that was ultimately attributable to the linked arrangement of cocks used on LMS, GWR and BR locos. Essentially on one of the gauge glasses, it had been reassembled incorrectly by a fitter, such that when operating the linked handle, one cock was open and the other closed. (rather than both being open, or both closed, according to position). The result was the two glasses read differently, but the crew then believed the higher reading rather than the lower one. The higher one was erroneous (essentially because the steam passage was shut and the water passage open, causing the water to rise in that glass). The result was a collapsed firebox crown. I'm away from references, but I think it led to changes in maintenance procedures. Such an accident would not have occurred with separate cocks in which each passage could be independently tested.

Re my earlier comment about try cocks "might as well not be there". Of course when you get on a loco you test them, just as you test any gauge glass. But while firing, if you need to know the water level, a normal gauge glass tells you that immediately, whereas the try cocks require manipulation to get a reading - and even then, you don't get to know the actual level, only its upper and lower limits. So in a practical firing situation they are of no use, in the sense I can't see you would ever use them to find the water level when you could just observe it in the glass. And if you have two glasses, you have an immediate indication of any discrepancy that would lead you to be suspicious of a false reading caused by a fault.

Tom

 

Of course if one guage glass fails it can be isolated and you can carry on using the second until you come to a suitable location where you have the opertunity to change it. If however you only have one and that fails you are not going to want to travel very far with only the tricocks to show you the water level.

Peter

 

Quite.

Tom

 

Its a kinda pointless discussion in that the stats demonstrate that either arrangement is adequately safe.
I suppose if one were being pedantic there ought to be three gauges, so that in the case of disagreement you could be reasonably confident which was correct.
As a matter of interest, have you ever had glasses differ, and what did you do about it?

 

I've had it happen twice. On the first occasion it was a set of Chanter Biomed gauge cocks. These have removable handles and the sleeve had been replaced on the top cock as it was passing. The person doing it had managed get the handle 90° out in replacing it so that, with the handle in the open position it was closed. Both glasses showed a correct level when cold but it was fairly obvious something was wrong when the loco was steamed and fairly easy to diagnose the problem and rectify it because you could operate the cocks independently. More recently I've had a problem with a glass giving a false reading due to a blocked passageway. It was possible to work out that the problem was with the top cock, again because they were independent cocks. We worked the loco to Grosmont with the one good glass where we declared it a failure. I've forgotten exactly what the problem was now but it was with the sleeve packing which obviously couldn't be rectified with it in steam.

 

According to RCTS, there were 3 firebox failures on S160s in Britain in 1943/4, including 2 on the LNER at Thurston and at South Harrow. Similar S160 firebox failures were reported from at least six other European countries as well as in India (broad-gauge variant) and North Africa. Where countries retained S160s for long-term use, I assume that modifications would have been made to tackle the design problems. Polish Railways reportedly reduced the boiler pressure from 225 to 185 psi.

 

I think all the S160 failures were down to the fact that US practice was to use screw down valves on the gauges and not cocks, certainly in the UK. With a cock you can instantly tell whether it is open or closed just by looking but with a valve you have to physically try it. UK crews weren’t used to this and, if they could see water, assumed they were open. The gauges were also of the Klinger reflex type and they can be hard to read, especially at night.

 

That’s what I have read about these engines.

 

I don't think we're just discussing safety here. It's also practicality and the ability each arrangement gives the fireman to continue to do their job in the event of a gauge glass failure. On the second point, while try cocks can tell you whether your water level is high (water level above top try cock), medium (water level below top try cock but above bottom) or low (water level below bottom try cock), in many circumstances that information is far more vague than you would want. In some cases (e.g. where you're coming up to the crest of a hill) you want a much more accurate indication of where the boiler water level is, rather than just which of the three potential ranges it sits within. Boiler management often needs to be more precise than "the level is somewhere between 1/3 and 2/3", and in those scenarios, having dual gauge glasses is an objectively better option because the failure of one gauge glass does not negatively impact your ability to do your job in all its fullness, whereas losing a gauge glass where your redundancy option is a pair of try cocks does