mott
Hi-poster
Posts: 151
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Post by mott on Mar 22, 2007 20:57:30 GMT
Hi Guys, this message is about the 14XX !! How can traction engines be allowed to occupy our space? They should have their own string. I am into the winter overhaul on the 14XX and gazing somewhat malevolently (Big word!!) at the valve chest. I have still been troubled by blows up the chimney when stationary, with the regulator cracked open , which indicates leakage of steam passed the valves or pistons and general inefficiency in the use of steam. My pistons seal well so it really has to be the valve seating yet when I open it up the valve chest appears in pristine condition. I have the option of fitting small springs under each corner of the valve from small holes in the buckle to improve valve seating but if I use them the resistance to the valves moving over the cylinder ports along with stress in the motion and wear to the bearings and pins really precudes this as a permenant solution. It does guarantee that the valves seat on the cylinder ports and timing can be accurate. So I am led to consider the buckles. they seem very large in the valve chest and the gap between the two is small as they reciprocate - posslbly not much more than1/16th" . certainly less than 1/8th". Steam pressure is needed to bear on the back of the slide valve to make them seat so are these over large buckles getting in the way and at the root of the problem? On the basis that there is "nothing new under the sun" has anyone tackled this issue and perhaps reduced the buckles in thickness etc or even thrown them out in favour of alternatives . I would be interested in opinions from 14XX owners. Mott
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sjtown
Active Member
Posts: 38
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Post by sjtown on Mar 24, 2007 20:58:29 GMT
hello Mott,
Have you any photos so I can have a look, would be handy to compare yours to my Winson metal.... Seeing as mines still in its re painting stage its not run for about a year, but it would only blow-by the valves now and again after being stationary and normally with a good blast of steam they seat properly.
Mine did this even before I brought it according to the man who originally bodged it together, but since then I now have the cast iron valves from modelworks instead on the original brass Winson ones and all the surface flattened and polished, but no work on the buckles... as far as I remember...
Steve
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mott
Hi-poster
Posts: 151
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Post by mott on Mar 24, 2007 23:43:23 GMT
Steve, Sorry no photos of the valve chest. My suspicion is that the volume that the buckles takes up within the valve chest is just too great and prevents the full steam pressure getting to the backs of the valves. I have filed off metal from the buckles to allow a better steam flow into the valve chest so will have to see if that improves peformance. Mott
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Post by Shawki Shlemon on Mar 30, 2007 12:19:08 GMT
I am building a Dukedog which has similar valve arrangement .I ran it on air and it started straight away. I wonder if steam entry into the valve chest impinge on the valves pushing them down and / or the valves have a large drop . In my case they just slide on the surface .The size of the buckles should have no effect as the steam will get under the valves . I ensured that the steam inlet was not directly above the valves or the buckles by making it rectangular instead of round . Just a thought .
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Post by Deleted on Mar 31, 2007 8:49:45 GMT
The gap between the valves will have no effect on the seating of the valves, check for free movement of the valve in the buckle; it must be completely free to move, you say the valves are brass. What are the buckles made from, perhaps differential expansion is taking up the clearance between the two? Below is a G1 Dean Goods I built with full Stephenson's gear, valves don't come much closer than this, working pressure 60psi. Sorry it's a bit of a crappy photo, the original was really underexposed. Good luck.
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mott
Hi-poster
Posts: 151
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Post by mott on Mar 31, 2007 17:33:09 GMT
Thanks guys. I suppose my point is that despite eliminating all these issues, we still get times when the valves lift and we use up loads of steam. It could well be partly driver error however and with the 14XX we have quite a coarse regulator. It maybe that its just too easy to open up too much at low speed and hey presto prime the boiler. This came to my mind this afternoon when I was driving a friend's Maid of Kent, I had unknowingly left the injector on and the level in the glass was high and when I came to a gradient , I opened the regulator and instead of getting more thrust had a spout of water out of the chimney just like the 14XX and this from an engine in perfect condition. Certainly the water level on the 14XX is critical and it is best run with a fairly low glass, which is easy to judge on a level track but where we have gradients problems can occur. Keeping the steam pressure high is also essential and in my experience if it is allowed to drop below 50 psi on the 14XX, you have to stop for a blow up but again this is experience of a track with gradients. Maybe on a flat track they do much better. Mott
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Post by BHMEpete on Jul 5, 2010 23:08:53 GMT
Can't help but resurrect this thread after having a read...
A fellow member at Brighouse has the 7.25" version, I think he bought it as a full kit of parts on Ebay. It steams very well with the huge Belpare firebox and runs well if it drops to 50psi, aside from the timing being slightly off. He's had to re time it several times on account of a slipping grub screw, he was told to pin it once set and although it hasn't slipped for a while, I'm not sure he's pinned the rocker cranks in question yet - needs further adjustment as it's only happy in full gear but it'll do for now, we're using it on a portable track this coming Saturday so won't dabble just yet.
He's just reassembled it after repairing the boiler which has very messy soldering as supplied, such that it hadn't penetrated the foundation ring properly in one spot and it blew with a gap either side like opening a sandwich, he fixed it with peening and rivets right through as per inspector advice. Aside from the quality issues it has a good amount of power if a little light on its feet - he's built a truck with a water tank so is fitting the side tanks with permanent ballast weight for adhesion. Although not an engineer he successfully built and fitted a steam brake to a seasoned club member's specification, works very well - running light engine it tries to toss you from the truck! With a load behind it's not as vicious ofcourse.
As an aside I was driving the thing Christmas day 2008, just a few of us having a steam up - and coasting down the steep grade into our balloon loop I got a huge flame from the chimney for a few seconds, like a big gas torch - a crack of the blower seemed to cure it. Never even heard of it happening to a loco before, was quite a surprise - the previous driver had run the fire low and I'd built it up before setting off. Whether it was dust in the coal I don't know but it evidently draws well! Didn't appear to cause any smokebox damage, just a very odd occurance!
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