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Post by andyhigham on Apr 11, 2020 21:33:51 GMT
I'm going to spray the chassis satin vermilion, the running boards satin black. I figured the satin finish will look less new.
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Post by andyhigham on Apr 13, 2020 11:51:56 GMT
Piston rings!!! The cylinders are cast iron, the pistons are aluminium. The right hand piston had a very well worn bronze ring (2.5mm end gap), the left hand piston had a 2mm section O ring flapping loose in a 3/16" (4.8mm) wide groove. I figure I have 4 possible choices 1) Speak to Clupet and get bespoke rings made 2) Machine the grooves to 1/4" wide and fit 2 rings per groove 3) String 4) Fit 3 x Viton O rings per groove
Viton Rubber O Rings: Widely used and the simplest types of seal they are found everywhere from plumbing installations to the space shuttle, they are common in engines and gearboxes, garden hoses, pumps etc. They can be used as face to face seals (like a gasket) or as shaft seals and facilitate both rotary and linear movement. Viton rubber has a particularly wide operating temperature range ranging from - 25 deg Celsius up to + 200 Deg C (higher for short periods) and a high degree of chemical resistance. It is highly suitable for use in engines and other areas where extremes of temperature and chemical exposure are present. Material Specification: Viton Rubber (FPM), 75 Shore hardness. Benefits: Excellent sealing properties and durability, wide temp range, high resistance to many chemicals and petroleum based fuels including petrol, diesel, LPG
Brand / Quality: Simply VIT O-Ring - High Quality Cross Section: 1.78mm Inside Diameter: 37.82mm Outside Diameter: 41.38mm
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uuu
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Post by uuu on Apr 13, 2020 12:40:25 GMT
I'd be interested to hear the results of your Clupet research - I think the original chap is gone - and don't know who is now doing them.
Jessie has a wide groove with two plain rings in it - so the arrangement must work (although with cast iron pistons specified). We've made some plain cast iron rings in the Pumphouse, and it seemed a lot more straightforward than we had imagined.
Wilf
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nonort
Part of the e-furniture
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Post by nonort on Apr 13, 2020 16:15:47 GMT
Somewhere out there is a video of the Steam Workshop making 'Clupet' rings?
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Post by andyhigham on Apr 13, 2020 16:33:50 GMT
I think I will go down the 2 rings one groove route, I'll speak to Blackgates tomorrow
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Post by steamer5 on Apr 14, 2020 0:56:38 GMT
Here we go... youtu.be/80jzsNM6olEThe biggest problem I see is they make it look easy! Has anybody given it a try..... Cheers Kerrin
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uuu
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Post by uuu on Apr 14, 2020 7:03:24 GMT
A chap brought some he'd made (for his Speedy) to the Pumphouse to show us. So it's possible. They looked good (as does everything he brings).
Wilf
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Post by andyhigham on Apr 20, 2020 13:23:30 GMT
I have the rings now, conventional type. I will widen the groove to fit both rings side by side. I notice there is no snifting valve. Correct me if I'm wrong but I think this could cause radiant superheaters to overheat when the regulator is closed.
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uuu
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Post by uuu on Apr 20, 2020 14:37:15 GMT
If they're going to overheat when coasting with the regulator closed, then they are also vulnerable when stationery, unless you've some cunning plan to pass something through them in the station.
So I wouldn't worry.
Wilf
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Post by andyhigham on Apr 20, 2020 14:38:51 GMT
Good point. Any other compelling reasons to fit one?
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uuu
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Post by uuu on Apr 20, 2020 14:47:44 GMT
They're more relevant in piston-valve locos. A slide valve can lift if there's suction on the intake side, but a piston valve can't.
Having a flow of something when coasting will keep cylinder lubrication going.
I'm sure there are some other reasons. Jessie does not have one shown - so unless someone else can come up with something good, I'll probably do without (although I'm proposing a modest superheat rather than incandescent).
Wilf
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Post by Roger on Apr 20, 2020 15:51:48 GMT
Good point. Any other compelling reasons to fit one? I think you risk drawing soot from the blast pipe back into the valve gear and cylinders. The locomotive is acting as a vacuum pump, and that will not only slow it down, but any leakage through the valves or pistons is going to cause a reverse flow since the cylinders are now creating a partial vacuum. Whether you consider those to be compelling reasons or not is a matter of opinion. Personally, I would have thought that it was better for a locomotive to a 'freewheel' when you close the regulator. I certainly wouldn't want ash in the cylinders either, but perhaps someone has experience of just how bad that gets?
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mbrown
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Post by mbrown on Apr 20, 2020 16:02:36 GMT
Talyllyn Railway No.7, Tom Rolt, has piston valves and no snifting valve (just rather inadequate by pass valves) and it rolls, as they say, "like a brick"....
The other locos have slide valves - whether flat on top or vertical between the frames - and coast very sweetly.
On No.7, a tiny crack of the regulator keeps enough steam passing through the cylinders to break the vacuum and let her roll. But I suspect a shifting valve of some sort would be a better solution.
Malcolm
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Post by andyhigham on Apr 22, 2020 8:48:11 GMT
After reading the comments on here and on Roger's speedy thread, I have decided to fit snifting valves directly on the steam chests. There is room on the back of the steam chest above the valve spindle (directly opposite the oil port). If I make them so the ball falls to the open position, they will double up as an after running cylinder lubrication point
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Post by andyhigham on Apr 22, 2020 17:41:38 GMT
I have a suitable design for the snifting valves. I thought "what if........"? I turned a boiler feed clack upside down, suck on the boiler connection and it is free flowing, blow and it seals. If it works with gob pressure it should with steam
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Post by andyhigham on Apr 22, 2020 19:20:41 GMT
I should have looked in 3 dimensions. The spot where I thought I could fit the snifting valve has a stud running through it. 2nd down on right hand side in photo 20200422_201607 by Sigma Projects, on Flickr
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Post by andyhigham on Apr 23, 2020 13:30:25 GMT
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Post by andyhigham on Apr 23, 2020 13:33:29 GMT
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uuu
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Post by uuu on Apr 23, 2020 14:45:31 GMT
Definitely better afterwards.
Wilf
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Post by Roger on Apr 23, 2020 14:53:19 GMT
Blimey, I can see why you wanted to repaint it. Mind you, it might have been authentic! Someone might have gone to a lot of effort to get it to look like that...
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