Templot Club Archive 2007-2020
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posted: 17 Dec 2016 16:16 from: gibbard d
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Hi everyone in a steam shed scene what type of rail would be used on inspection pits and ash pits? would it be bullhead rail fitted to chairs that are bolted to metal beams or flat bottom rail bolted directly to the supporting beams? I haven't decided yet whether ill model an old BR shed or a preserved steam shed, would there be differences? also the same questions regarding turntables. the main yard area will be constructed from bullhead rail using c&l chairs, if the pits use flat bottom rail are the rails compatable or would I need to make custom joiners or even solder the rail ends together? |
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posted: 18 Dec 2016 23:03 from: Tony W
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I have seen both Flatbottom and Bullhead rail used for ash pit / inspection roads. Bullhead would be more typical in steam days, however the supporting way-beam would be made of timber in the same fashion as on bridge decks using bridge chairs, but set into the brickwork so that the inner edge of the way-beam is flush with the inside of the pit. Bridge chairs have a base that is nearly square as opposed to the standard S1 chair, which is much wider than it is long. Flatbottom rail can be spiked or bolted directly to the way-beam surface as it has continuous support. Sometimes a low hight rail section is used. Turntables are not something of I have much experience, but similar considerations would I suspect apply. As long as the running surfaces align, mixing rail sections is quite permissible. Special cranked fishplates are made for just this eventuality although rails are often butt welded together these days. I would not recommend butt soldering two rails together as the resulting joint will not be very strong, guess how I know? Regards Tony. |
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posted: 19 Dec 2016 00:16 from: gibbard d
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Tony W wrote: Bridge chairs have a base that is nearly square as opposed to the standard S1 chair, which is much wider than it is long.HI tony thanks for your advise. would a L1 chair be suitable ( I believe that was the chair Norman Soloman used in Right Track 10 for limited space within the turnout). Also something I forgot of my original post he stated that the keys on the chairs face the oncoming traffic on a main line, how you a yard area be keyed? would it just all be keyed in the same direction or is there a different type of key used for bi directional running? I'm assuming for 00 it'd be a case of keyed all in the same directions using C&L's standard chairs except for around fishplates, I know the keys are inserted the opposite side to allow room for the fishplates many thanks Daniel |
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posted: 19 Dec 2016 01:45 from: Martin Wynne
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Hi Daniel, Yes L1 chairs are bridge chairs. They are the ones used on waybeams such as along the edge of inspection pits. Keys are tapered wedges which are driven (hammered) into the chair in one direction, with the result the thick end remains protruding in the opposite direction. The rules from railway permanent way staff all refer to the direction in which the keys are driven. Modellers sometimes refer to them the other way. In sidings, yards engine sheds, etc. keys are usually driven towards he nearest rail joint. But you will find masses of evidence contradicting this as loose keys have been replaced over the years. It is important to prevent a rail creeping through the chairs, because it causes the essential expansion gap at the rail joint to close up. There is then a risk that the rail will buckle when it expands in hot weather. The general creep of rails is in the same direction as the direction of traffic. On double track the tapered chair keys are therefore driven into the chairs in this direction, and any rail creep will tend to tighten them in the chairs. Note that this means the direction in which the keys are driven (hammered) into the chair. The result is that the thick end of the key remains protruding from the chair pointing in the opposite direction. The reason the rails move in the direction of travel is because of the way the rails flex under load and get pushed forward by the wheels. It is similar to what happens when rolling pastry -- the whole mass moves forward on the board in the direction in which it is being rolled. However, there are sometimes situations where rails are found to move backwards -- for example on the inside rail of sharp curves and on steep rising gradients. If a situation is found where the keys frequently work loose, some or all of them will be turned round and driven in the opposite direction. On single lines or where traffic is bi-directional, the usual rule of thumb is to drive the keys "towards the joint, towards the station, towards the river". That means on level track between stations the keys are driven into the chairs towards the nearer of the two rail joints in each rail length. Approaching a station, where trains are braking or accelerating, most keys are driven towards the station. On steep gradients, most keys are driven downhill. But on any track, on the chairs immediately adjacent to a fishplate at a rail joint, the keys are driven in towards the fishplate, because it is physically impossible to fit them the other way. Just to repeat, the thick end of the key remains protruding from the chair in the opposite direction to the direction in which the key is driven into it -- this can lead to confusion in describing the hand of model chairs with moulded keys. regards, Martin. |
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posted: 31 Dec 2016 11:30 from: philchudley click the date to link to this post click member name to view archived images |
Hi Regarding the type of chair used on turntable decks, this photo of Bude (LSWR/SR/BR) may help: 672_310627_380000000.jpg  The bullhead track is laid on longitudinal baulks and chaired using standard chairs (3 bolt in this case) All the best for 2017 Phil |
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