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Post by ejparrott on Apr 29, 2014 11:24:10 GMT
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 I've been pondering doing this with my Manning Wardle, having had problems with my hunslet. After Mr Ashton doing wonders with my valve gear, it would be a shame for it to be let down by valves which won't stay on the faces. My other thought was to apply a lightly sprung pad to the back of the valve. I have the benefit of room on the MW, which the Hunslet is lacking.
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Post by iompeveril on May 5, 2014 12:18:05 GMT
I've given my Isle of Man loco. another steaming today, and I'm pretty sure now that the problem is lubrication. Let me tell you how arrived at this conclusion.
Because of the severe priming I had previously experienced on starting, I decided to adopt a different approach. The front cylinder covers are drilled & tapped for dummy lubricators (not fitted yet) so I removed the blanking bolts from the holes and squirted in a lot of cylinder oil. I also squirted quite a bit down the blast pipe, and I gave the mechanical lubricator several turns to make sure the oil delivery from that was well primed.
I closed all steam valves apart from the regulator (with the engine in mid gear) and let her start to make steam and blow through the valves & cylinders. Quite a bit of water was expelled, but not in the violent way I had experienced previously. After the steam circuit was well warmed through I closed the regulator and let the pressure build up. While this was taking place I replaced the blanking bolts in the cylinder covers.
When I started the engine there was still some priming, but nowhere near as bad as I had experienced previously. She settled to a steady beat and the pressure and water level were maintaining well, and I was easily able to top up the boiler using the axle-driven pump. However, after a while she began to misbehave again - water started to disappear more quickly and the slight 'oiliness' disappeared from inside the chimney. When I took the lid off the mechanical lubricator I discovered why - the shaft with the cam that drives the pump was not rotating, only oscillating. If I gave the shaft a turn it would run properly for about one revolution and then just start oscillating again.
Because the engine had been happy when I first started it (and it had plenty of oil in the valves & cylinders) but then became distressed when the lubricator failed, it seems that is the problem. Because some work had been done previously on the lubricator I had assumed that it was OK, but clearly not. So what do folk deduce is the problem with the lubricator from the symptoms I've described?
Needless to say the valves & cylinders have had another good dose of cylinder oil on 'shutdown' and I'm pretty sure that if I can correct the lubricator fault all will then be well.
Peter Jordan
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Post by iompeveril on May 5, 2014 14:16:10 GMT
I've just dropped the coupling rods from the rear crankpins so that I can spin the wheels easily to try and drive the lubricator.
The lubricator takes its drive from the same eccentric as the water pump (driven by an eccentric on the back axle.) I've measured the stroke and it is 9/16" which I would have thought should be plenty to drive the lubricator.
From the point where the horizontal drive attaches to the vertical bar from the ratchet to the centre of the camshaft driven by the ratchet is 1 and 5/16" and the outside diameter of the ratchet wheel is 7/16".
I thought I'd provide these dimensions in case they can help anyone work out what is wrong.
Peter Jordan
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pault
Elder Statesman
Posts: 1,496
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Post by pault on May 5, 2014 16:31:40 GMT
Hi Peter It sounds like the lubricator is not doing a full click or the ratchet that stops the lubricator going backwards is not doing anything. Can you turn the lubricator a full revolution in both directions? If you can then another ratchet which is normally mounted on the tank is not doing its thing. If you can only turn the lubricator one way it suggests that the lubricator is not going a full click. You may be able to move the drive rod to another hole in the arm, up towards the ratchet. This would increase the swing of the drive arm allowing it to pick up the next tooth. A photo would help here.
Regards Paul
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Post by iompeveril on May 6, 2014 14:06:52 GMT
I've now stripped the water pump and mechanical lubricator assembly out of the loco. so that I can investigate further what is going on. I'll report back in due course.
Peter Jordan
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jma1009
Elder Statesman
Posts: 5,901
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Post by jma1009 on May 6, 2014 23:30:34 GMT
hi peter, whilst i agree that erratic lubrication may be the cause of some problems, i am afraid i suspect something more fundamental may be at fault internally. so far as the lubricator is concerned you dont state whether it is roller clutch or pawl design or the jim ewins type. if roller clutch type i suspect the shaft wasnt dead hard and has worn and allowing the roller clutches to slip. i still think you need to strip the loco down and examine all the internals of the cylinders and valves etc carefully. erratic lubrication wouldnt of itself cause all the problems you have described. cheers, julian
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Post by iompeveril on May 8, 2014 17:24:27 GMT
I think I'm now making some progress with the loco. I have got the mechanical lubricator working again - the problem seemed to be with the pawl (or 'click' as we clockmakers like to call them)that is supposed to hold the ratchet once it has rotated slightly. This was worn at the tip and after the wear was stoned out and the click refitted the lubricator worked perfectly. I spent quite a lot of time this afternoon whizzing the driving axle round by hand and the lubricator never faltered and oil was delivered through the pipework.
So I'm pretty confident that, at the next steaming, all will now be well on that front.
However, I've also been thinking about the type of oil to use in the lubricator. Presently I'm using some cylinder oil I already had in stock from a 4 inch Foster traction engine that I used to own. This, of course, was a 'saturated' engine, although the cylinder was steam-jacketed. The IOM 2-4-0 has a superheater but I've been told that the oil I have is perfectly satisfactory, as small models never reach the kind of temperatures that require special cylinder oil in large, superheated engines. While there may well be some truth in this, I did wonder if, with cast-iron cylinders and pistons with iron rings, the thicker oil used for superheated engines might be better for sealing everything where it needs sealing.
What do folk think/advise?
Peter Jordan
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uuu
Elder Statesman
your message here...
Posts: 2,812
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Post by uuu on May 8, 2014 17:58:16 GMT
Stick with the oil you have.
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Post by Deleted on May 8, 2014 19:03:20 GMT
Hello PETER..........use an oil appropriate to the situation..If you have a high degree of Superheat then any lesser an oil will tend to carburise within the hotter working environment ( Example..the final GWR Castles (4-row Superheaters) used a different grade of oil than their predecessors (with 3-row superheaters).......However if yours is say just a 1-pass "Hair dryer" type of thing then yes, continue with what you're using now.....Please don't make the mistake of imagining the oil to still be "Thick and sticky" after it's been mixed-in with the main steam flow and thus will "seal where it needs sealing"... If you have a scored bore/broken rings/warped slide valves then no amount of thick oil is going to cure that !!
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Post by ejparrott on May 9, 2014 7:50:49 GMT
I would be very suprised if the oil you have wasn't suitable for use in this engine.
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Post by wdiannes on May 9, 2014 11:38:28 GMT
On my lubricator the original builder had taken the drive off the valve gear. As a result, the lubricator wasn't always advancing if the engine was "notched up". I didn't find the problem until I put a crank on the oiler and noticed it stopped advancing sometimes. I moved the mechanical drive to the crosshead to eliminate that problem. The second problem with an intermittent check valve in the oiler. I found that when I noticed the level in the lubricator was higher after a run than before. I tried cleaning the check valve but it still wasn't reliable so I installed a new oiler and secondary check valves in each feed line - no more problems.
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Post by Deleted on May 9, 2014 15:06:06 GMT
Hello DIANNE---------has the snow gone now ??........Does anyone fit a stop valve between the oil feed point and check valve ??
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nonort
Part of the e-furniture
If all the worlds a Stage someone's nicked the Horses
Posts: 277
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Post by nonort on May 9, 2014 15:53:03 GMT
On an old engine that I once restored had been standing for about forty years the lubricator was completely empty but for a very small treacle at the bottom of the tank. On first steaming this engine having removed and rebuilt the lubricator and several other bits and pieces. It primed like a good'n water every where except in the boiler this only happened at near blowing off pressure 80 psi. On further investigation it was found that as the boiler cooled down it created a vacuum and drew the contents from the lubricator into the boiler via the hot header. I washed the boiler out by removing the dome and boiling up a washing soda mixture removing the steam oil it took several brew ups but eventually the priming stopped. A sniffter valve in the wet header solved the vacuum problem. I have been using car tyre valves for lubricator check valves for years 'free' from a local tyre fitter.
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Post by wdiannes on May 9, 2014 18:32:59 GMT
Hello DIANNE---------has the snow gone now ??........Does anyone fit a stop valve between the oil feed point and check valve ?? Yes, the snow has gone (except in the shaded areas). If you fitted a stop valve in an oil line you would blow something apart if you ever forgot to open it - not to mention doing-in your rings.
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Post by Deleted on May 9, 2014 20:46:55 GMT
------true, but the idea is to leave it open at all times closing it only when/if the oil check valve sticks open and steam back-feeds into the lubricator reservoir....This allows you to remove the check valve to service it OR fit another one with the loco held in light steam.....
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Post by Deleted on May 9, 2014 20:47:06 GMT
------true, but the idea is to leave it open at all times closing it only when/if the oil check valve sticks open and steam back-feeds into the lubricator reservoir....This allows you to remove the check valve to service it OR fit another one with the loco held in light steam.....
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Post by iompeveril on May 10, 2014 9:16:15 GMT
In response to jma1009, I don't think the problem was so much 'erratic' lubrication as no lubrication at all!
When I had completed the repair to the lubricator I decided to check the delivery pipework as well. As the lubricator is mounted beneath the cab footplate, there is quite a long run of pipe from the lubricator to the steam chest. This is fitted with a check valve part way along, and after I removed the pipework I took the check valve out to make sure neither length of delivery pipe was blocked. I expected to have to clear oil out of both lengths of pipe, but no - they were already absolutely clear. So the lubricator had been doing nothing at all to feed the engine!
I cleaned up the check valve and reattached the pipework to the lubricator but not to the steam chest - instead I let it dangle towards the floor. By dint of spinning the back axle for a long time (rather hard on the arms) I eventually got oil flowing out of the check valve, so I'm confident now that all should be OK.
I just need an improvement in the weather now to allow me another test steaming.
Peter Jordan
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smallbrother
Elder Statesman
Errors aplenty, progress slow, but progress nonetheless!
Posts: 2,269
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Post by smallbrother on May 15, 2014 13:07:29 GMT
Whilst my Polly 1 went through its hydraulic and steam tests recently, it wasn't going at all well on the track.
Pressure dropping as soon as we moved off, big flat spot so it needed a nudge, lots of steam up the chimney, not making steam on the run but ok when stationary.
Have taken off an "o" ring from the piston. The groove is about 3mm deep but the old ring measures just 2.9mm thickness. Have just fitted one new ring which measured 3.1mm thickness. With a bit of luck I can change the other one this afternoon and get her on the track this evening.
Wonder if she will do the biz?
Fingers crossed.
Pete.
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Post by Roger on May 16, 2014 7:31:00 GMT
Someone mentioned a different type of seal a while back that might be worth a try. These are Quad Rings and appear to be used in the same situations that 'O' rings are. I would imagine that they would seal better and be more flexible due to their cross section.
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Post by iompeveril on May 18, 2014 8:11:38 GMT
The improved weather allowed me to steam my Isle of Man loco. on Friday and, with cylinder lubrication restored, she is a reformed character. I had no trouble keeping the water up in the boiler when needed. She ran well on the 'rolling road' for an hour with no problems, and I finished up with a nice, oily inside to the chimney rather than the dry, grey one of previous times.
Mind you, the hot oil appearing at the chimney was pretty thin, so I'm tempted to try superheater oil just because I think it might give a better performance.
Peter Jordan
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