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posted: 29 Dec 2017 01:09 from: DerekStuart
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I wonder what others make of this. The single slip at the bottom left shows one of the blades seemingly running behind a check rail. At first I thought it might be a short, loose heel blade- which it still might be, even if the joint cannot be seen- and thus the check rail is clear of the moving part. But then how does the outer 'slip' rail get checked? Surely the other running rail cannot perform this job- can it? This particular item (Kings Cross, middle portal, East road) seems to have been removed some time after WW2. I don't know its copyright status so I'll just add the link if anyone's interested. http://www.cntraveler.com/stories/2016-01-11/the-flying-scotsman-worlds-most-famous-train-back-after-a-53-year-retirement |
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posted: posted: 29 Dec 2017 09:23 from: JFS
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Er? just an ordinary Outside Slip? Am I missing something? Best wishes, Howard |
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29 Dec 2017 09:23 from: Ian Allen
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Derek, This looks like an outside single slip, albeit with a short lead from the switch blades, so in this instance the switch blade can provide checking for the stock rail for that route, although there may be a machined check rail out of shot which would be tapered to fit against the switch blade. Ian |
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posted: 29 Dec 2017 09:33 from: Martin Wynne
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Hi Derek, That outside slip is an interesting bit of pointwork, it's unfortunate we can't see more of it. Normally if someone came up with two V-crossings so close together it would be "no way". Here we can see that space for the switch was so tight there was no room to move it further back. Moving switch blades can't in themselves be used as check rails, the checking forces could damage the stretcher rods and detection gear. However, loose heel switches can be quite short, allowing check rails to be connected into the back of them. That's sometimes necessary in a turnout where the turnout curve is sharp enough as a running line to need a continuous check rail. On the GWR the casting which connects a check rail to the back of the switch rail at the heel, relieving it of any checking forces, is called a "check lump". The switch rail on the right is clearly very short, so we can assume the opposite one is the same. Also, the check rail on the right is very short, spanning only 4 timbers. It looks barely long enough to properly check the inner crossing. The great advantage of a terminus station is that everything stops. Nothing is going to be running over that slip at 60mph. cheers, Martin. |
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posted: 29 Dec 2017 17:01 from: DerekStuart
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Thanks for the comments, chaps. So it must be some sort of very thin "bar" used as check rail, just out of sight of the camera. Presumably this would be similar to the check "rail" used on FB on curves. This particular piece of track work has had an "interesting" history. It has been like this initially, then it has been a fixed crossing AND a moving K crossing (which one came first I don't know). It works out to be K:7.08 V:5.67 according to the map, with its partner being K:7.1 V:10.62. Also, just out of interest, it has also had quite an interesting history of changes to the check rails. Many thanks Derek |
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posted: 29 Dec 2017 17:06 from: DerekStuart
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I've just found this picture- unfortunately someone has parked a train over most of it, otherwise it would be a good photo. It shows the slip is checked along its length. A checked rail normally would surely indicate a tight curve. Is this the only moveable K slip with a tight curve to it? http://www.flickr.com/photos/david_christie/13148250215/ |
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