Air Pump Failures

Not an 'official' explanation, but personally I'd be apprehensive at the thought of using flexible pipes to carry high pressure steam pressure. I have seen a carriage heating pipe burst, and they only carry 50 psi or so.

 

What about most LMS locos, BR standards and a few LNER ones, all of which have steam brakes on the tender with steam at full boiler pressure? I'd like to see the explanation of why air pumps on tenders are no longer OK, simply out of curiosity.

 

A while back, there was talk of kitting out one of Didcot's engines with a pump in the tender, so I'd most definitely like to see an explanation as well. Surely, as long as there's a shut off cock? I mean, it's not as if they've banned new engines from having gauge glasses...

 

And the FR is still allowed to run Fairlie engines.....and even build new ones and what about the Garratts?

Also - all you lot harshly critical of air brakes - Steam locomotives have been fitted with air brakes, extreemly sucessfully, since the 1870's

See: http://en.wikipedia.org/wiki/Air_brake_(rail)

 

Regarding steam hoses between engine and tender, I can't see why this should be a problem. In my industry modern wire-armoured hoses are taken to higher pressures than this without problem.

As far a being harshly critical of air-brakes goes, they are here to stay. One day soon there won't be any main line certified vacuum braked stock. Even if there was, there'd be no non-steam loco's so-equipped for stock movements or rescue.

The problem I raised and that I'm trying to address is that of current day reliability. Yes air-braking on steam powered trains has worked fine for years abroad, and in pre-grouping companies here. So - what's going wrong, and how do we fix it - are the questions that we need to answer, before the movement suffers any further damaging incidents on the mainline.

 

Re Sheff and Steve's postings. Flexible hoses can carry a lot of pressure agreed, but when it is steam I am still wary. I still remember (the late) John Axon affair.

 

You always need to be wary of steam because, as you say, it can kill if it is allowed to escape or unleashed. But that fact only puts it alongside an awful lot of other things that we live with on a daily basis.

 

8-Pot - I don't think you can equate the failure of a brazed joint in the cab feeding a direct acting steam brake with a steam hose under the cab supplying an air brake pump. The first resulted in the tragic runaway, the second would result in clouds of steam and the train brake stuck on.

I don't think this hose debate is really relevant though, as I doubt anyone would want to sacrifice water capacity to fit air pumps in the tender unless there was a very strong case for doing so?

 

Not just in pre-grouping days though, all those carriages etc were still used by the SR among others, even into BR days. Granted they were not 'standard' but they were still there. Railways on the IOW have always used the air brake for the best part of a century.

I am still not convinced it is that big a problem...you have had a few high profile failures and that is it. How many have been caused by poor quality coal? Are there any statistics for how many air systems failing compared to other parts of locomotive equipment?

 

I think the point Sheff is trying to make is that the optimum failure rate is Zero. Any exchange of ideas and mutually agreed improvement can do no harm so why not share engineering know how in order to avoid these failures in the future.

Yes these things happen, but maybe some failures are avoidable...

 

Most air pump/ compressor failures in this country are due to poor or non-existent lubrication. I notice that Tornado has its air pump steam cyl lubricator in the cab.
Alternatively, why not plumb it in to the mechanical cylinder lubricator?

 

A good idea but the pump has to run when the loco is stationary and, to some extent, vice-versa. I know very little about air pumps but the one on the NYMR S160 had its own mechanical lubricator. Is this not the norm?

 

Thanks Tracky, that's exactly the point. Just one incident like Ludlow can do enormous harm to the future of mainline steam. If we can, as a movement, come up with a more reliable compressor system, or a suitable means of back-up, all the better. For instance, Tornado has two air pumps, so they see this as a weakness, but being a new-build they have the scope to incorporate such a feature more readily than on a retro-fit.

Of course there's the solution already employed in some cases of dragging around a 120 tonnes of paraffin-powered insurance, but I think most of us would prefer not to do that, and the extra cost in terms of loco & crew hire plus the commensurate loss of seating capacity all make it a duff answer for me.

So let's try and get to the bottom of why air-braked steam appears to be failure-prone and come up with some ideas. Then maybe Ian or someone can tell us is they have any merit? It doesn't cost anything to rack our brains occasionally. (I think there's maybe one or two on here who's only reaction to a mainline failure is annoyance that they stood in a field for a few hours and didn't get the photo they wanted).

 

We need to begin by listing all known air pump failures, and what components broke, then see if one part stands out above others for being unreliable. Not entirely straightforward when comparing different types of pump I know, but perhaps it is a start?

 

60009's pump has arrived at the works for overhaul. The pump has been stripped, examined, reported upon, and the owner sanctioned the repairs.

Works overhaul of the pumps is becoming a necessity, they are like any other component on a steam locomotive...they require maintaining, and the knowledge to carry it out correctly.

Many of the air pumps on mainline locos are of Polish origin, (as the main Railway capable of supplying air pumps in the quantity required), and their quality of engineering has subsequently been found to be of dubious standard in many cases, which is one of the main reasons for their in-traffic failures. As the original importer of the pumps, we have seen many of the failure 'traits' with these pumps, and as such, have ensured that our own locomotives air pumps receive the attention that they require, other loco owners are now using our experience to their own advantage by returning them for overhaul.....most of these pumps were originally sold on in ''as removed from loco, no work carried out'' condition.

 

I agree Stu, and not just pumps but other failures of the system too. I've done a search for possible alternatives to the recip pumps, but need to get around to finding a clear and concise way of posting it on here - no one wants to wade through reams of techy stuff I'm sure.

Ian's report above is also interesting. Perhaps some sort of standard maintenance regime needs to be proposed by those with the knowledge e.g. Ian and then implemented by the relevant loco owners? Maybe on an hours-run basis? I wonder if there is sufficient commonality of amongst pumps fitted for Rileys to offer a pump exchange system to avoid loco's being o.o.s. whilst pumps are serviced?

One thing that surprised me slightly was how many main line loco's are air-fitted according to the UK Steam site. 12 out of 29 currently it would appear.

 

it's all very well doing trouble shooting analysis on these things and looking for alternative equipment but you have to remember that 'westinghouse' style pumps and brake systems have been around for a very long time. They were the norm on the majority of steam railways so the equipment, as such, has a good and proven track record. Rather than looking at the individual pieces of kit and trying to find alternatives that may not be 'tractionised', you perhaps should be looking at the history of it. Where has it come from? Was it overhauled before being put back into service? If so, who by? These would all be a good starting points. I suspect that much of it will have simply been cleaned up and proved to work at that time rather than have been stripped down, carefully examined and all necessary parts replaced or re-manufactured.
I used the word 'tractionised' above. Taking ordinary industrial equipment and fitting it to railway vehicles has a history of failure. Things invariably need modification before being suitable for railway use and the term I believe is known as tractionising the kit. We had similar problems in mining. We generally had to make normally reliable commercial industrial equipment 'pitworthy' before it became reliable in a mining environment.

 

I don't disagree with any of that Steve. IF the existing pumps can be made reliable AND kept that way by planned maintenance then that has to be the best solution.

 

Some none SG railways have used air breaking for a long time. Perhaps this discussion should hear from them as well. The Rhydol have recon'ed Polish pumps on there engine, as I have not heard of them being too much of a problem, other that aesthetically, and the Talyllyn and Leighton Buzzard both make their own in house compressors, the TR one having a very Westinghouse appearance, though only single stage air, and they have had orders from other railways world wide for supplying them.

 

To my knowledge all (or most) Dutch steamloco's use (west)german air-pumps.

I can't think of any failures with main-line loco's in the recent years. With the SHM I can't think of any failures in the past.

We have one line (STAR) in the Netherlands who has East European steamloco's and the VSM has some East German loco's although most of their loco's are from West Germany, I do not know about their experience with East European air-pump.

Paul Bender