My problem loco.

[iompeveril]

Hello everybody.

I've just joined the forum and hope some kind folk might be able to help me.

Last year I was fortunate enough to obtain a second-hand 5 inch gauge model of an Isle of Man 2-4-0 tank, one of my favourite engines. Over the winter I've had some issues with the axle-driven boiler feed pump and the mechanical lubricator sorted, and also added some external details to make the model more authentic in appearance to the livery that it carries.

However, some recent test steamings on my 'rolling road' have shown that the stunning appearance of this exhibition-quality model hide a very mediocre performance, and I suspect this is due to wear in the cylinders/pistons which are cast-iron. When cold the wheels can be turned very easily, and when in steam the exhaust beat is not pronounced. If I put a bar through the wheel spokes to stop the wheels turning, put the engine in full forward gear and open the regulator there is a loud roar of steam up the chimney. When running the engine also appears to consume far more water than I feel it should.

All of these symptoms are similar to those I had with a 5 inch gauge 'Speedy' some years ago - the problem with that loco was completely cured by repacking the pistons with graphite yarn., as the pistons and cylinders of that model were gunmetal. I'm thinking this current model needs similar treatment, and I'm considering replacing the cast-iron piston rings with PTFE yarn. Does anyone have any experience with this (or the problem I have) and can offer some advice, please?

Peter Jordan

[Deleted]

Hi Peter,

If the cylinders are cast iron then proper cast iron rings are really the best and should last for years. It's possible that one or both of the valves (probably slide valves?) are leaking. Maybe the port faces are scored or one valve is not seating properly. You do mention a problem with the lubricator which could have caused damage through lack of oil.

John

[jma1009]

hi peter,

sorry to hear of the problem with your loco. it is a lovely design and many have been successfully built to the mike casey design.

if to mike's drawings the axle pump is operated by a spring operated 'shoe'.

please do not put a rod through the wheel spokes then open the regulator. this is very dangerous.
instead there is a well known formula for checking blow on valves and pistons as set out in the 'Handbook for Railway Steam Locomotive Enginemen' (p.95 in my copy). cast iron pistons with cast iron rings is always the best way of making a steam tight seal in cast iron cylinders. if the fit of the pistons isnt ok then stuffing the piston ring grooves with PTFE or any other soft packing isnt going to solve anything.

the loco will have Allan valve gear which isnt the best valvegear but ought to be ok if properly made, assembled, and set.

from your description i suspect that nothing short of a major strip down of the chassis is required and inspection of the cylinders, valves, port faces and checking that all the valve gear parts are made and assembled as per the drawings.

cheers,
julian

[ejparrott]

Where are the slide valves on an IOM engine I can't remember, have a suspicion they are inside vertical face, same as my Hunslet?

[jma1009]

hi Ed,
yes, inside vertical steam chests, though as the wheels are outside the frames the cylinders dont have the long steam passages associated with the Hunslets.
cheers,
julian

[Deleted]

Something like this ?? >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> ------------------------------------------------------------------------------------ and this might help also >>>>>>>>>>>> www.youtube.com/watch?v=fgbMKGGiHp0

[Deleted]

473?

[Deleted]

Nice locos with lots of character.. Yes, as per the others it's got to be iron piston and rings in an Iron bore.........A faulty lube pump wouldn't have helped matters.. >>>>>>>>>>>>>>>>>>>>>>

[pault]

It may well be that you just need to give it a good dose of oil which as well as lubricating helps to seal the valves. With vertical valve faces the valves can fall away from the faces unless they are balanced or have a spring holding them onto the face. It can be difficult to get them back onto the faces. This could also account for the lack of resistance when cold.
Personally unless the bores are scored or the rings broken I would suspect the valves rather than pistons. Any chance you could post a video of the loco in steam

[marshall5]

Peter, the first thing I'd do is take off the cylinder covers and remove the gudgeon pins from the crosshead. Then slide the crossheads forward - on some engines (not sure on "Peveril") you can push them forward enough to expose the rings. Pity you didn't post a couple of hours earlier as I could have asked Mike Casey at the WLP today. When I bought my Milner Hunslet the cast iron rings were firmly rusted into the piston grooves and gave the symptoms you describe, a bit of cleaning up and new rings cured it. If that doesn't work then it's likely to be the valves. Wasn't this the engine you bought from Antique Steam last year? Cheers Ray.

[ejparrott]

I thought so, similar symptoms as my Lilla, also vertical slide valves. In my experience, it was gunged up old oil on the port face holding the valve off. To rectify I flooded the clinders with WD and kept working the engine round, eventually softened it and cleaned it off. One thing I do find and always have is that it needs a good burst of steam to get the valves up on to the faces, and the trick is to shut the regulator quick enough so that it doesn't slip. If you listed to TR No. 1 especially she suffers from the same thing, and you can really hear the 'slap' as her valves come up and on to the port face.

[jma1009]

hi ben...473... i appreciated your comment! yes definitely 473!
the IOM Beyer Peacocks are lovely locos.
i have often thought about building one.
cheers,
julian

[Deleted]

--------- like this ?? >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> www.youtube.com/watch?v=neqKatGJYKk >>>>>>>>>>>>>>>>>>>>>>>>>> and for pure Southern nostalgia I give you this}-------- www.youtube.com/watch?v=yd_3AlPQc6c <<<<<<<<<<

[iompeveril]

Thank you to those of you who have replied to my query, especially to Julian for drawing attention to the piece in the BTC publication. And yes, Ray, this is the model I bought last year.

I think I will have to do some more investigating along the lines that folk have suggested. The engine is about 22 years old, so it is possible that new piston rigs might be required. Question is - as I understand that castings for this model are no longer available, are the rings a 'stock' size available from model engineers suppliers such as Reeves?  

One thing that can't be helping is that the engine does prime a lot on starting, and this must be washing a lot of the lubricant out of the cylinders. Any tips for helping prevent this happening?

Peter Jordan

[Deleted]

Make sure that the boiler innards are free from any residual greases or flux ( Boil-up and a good, hard blow-down to empty a few times )..Use a clean water supply----Con sider some water treatment tablets/ powders------ keep boiler water level at a lower level when starting ---- investigate the possibility of re-locating the main steam take-off point away from the high water level....Slower opening rate with the regulator?? ---- We had a similar thread not so long back...

[ejparrott]

You'd need to provide us with a lot more information to be able to help with priming. I assume the engine has run before? That would say to me that it's not a cleanliness issue with the boiler as with a new boiler.

[jma1009]

hi peter,
i dont think it would be 'priming' on starting instead it is more likely to be steam condensing in the steamchests and cylinders. due to the sloping steam chest and particularly if the valves dont seat straight away a lot of water will collect in the back of the steam chest. if no drain cock is fitted to the lowest point of the steam chest this accumulated water will eventually go up the blast pipe when the valves seat.
don young had exactly this problem on his 5"g FISHBOURNE he built with vertical valves between and no drain on the steam chest.
you have a relatively large dome and high Stroudley type regulator inside and there should be no local pressure drop in the dome that otherwise might have a tendancy to lift water.
the arrangement of the valves on the IOM locos have to put up with quite a lot of strain having no tail rods (i think) on the mike casey design. quite often the valves are extended downwards to be supported on the bottom of the inside of the steam chest - this feature of fullsize is sadly often omitted in miniature.
cheers,
julian

[marshall5]

Hello Peter, Regarding the 'priming' - is this just on starting? If so could it be that the cylinder drains are simply not coping with the amount of condensate? If the loco's priming all the time I suggest you follow Hagley's advice but, as it isn't a new boiler, flux etc is not likely to be the cause. Of course a previous owner may have tried to "clean" the boiler and some contamination remains. Apart from blowing down a copper boiler should need no treatment unless in an very hard water area. IIRC Peveril has a very short gauge glass and it is easy to be tempted to overfill the boiler. Re- the castings, they are still available from Jimmy Woods in NZ as far as I am aware. On the piston rings, I too, once had a 'Speedy' with soft packing piston 'rings' but that wasn't unusual when it was designed. I'm pretty sure Peveril was designed for C.I. rings (to be honest I forgot to ask Mike yesterday) and wouldn't recommend PTFE in C.I. cylinders having seen those in a friend's loco ruined by just a small amount of rust. They're probably fine in bronze cylinders. sorry I can't be more help. Ray.

[marshall5]

Peter, just a thought, a couple of years ago I purchased a very sad 'Dart' which had the rings rusted solid to the bores. After several weeks soaking with a 50/50 mix of brake fluid and diesel oil I was able to free them up. If, on your Peveril, the rings are simply seized into the piston grooves rather than worn I suggest you close the draincocks and pour this mixture down the blastpipe. Let it soak for a few days ,topping up as necessary, and then steam the loco letting the cylinders warm up for a while. With luck the rings will 'unstick' and spring back to seal the bore. Worth a try and no harm done if it doesn't. Hope this helps. Ray.

[wdiannes]

I had a very similar problem last year with a new-to-me 1.5" scale American. It was confusing and took me months to sort out.

In my case, the original problem had been intermittent failure of the mechanical oiler and check valves. The lack  of oil and overabundance of condensation in the cylinders damaged the cylinder bore and piston rings. There were also steam leaks in the smokebox plumbing that added to the blow-by from the cylinders and one eccentric that had slipped and screwed up the timing.

Multiple problems can drive you crazy in sorting things out!

(I replaced cast iron rings with O-rings, replaced the mechanical oiler. rebuilt the smokebox plumbing, reset the timing, and the American ran like a charm when the last  of the problems were resolved.)