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| If they are not there, then one HOT day, the run will be thwarted by a damaged track. The curves may go outwards and the tangents may assume an “S” shape or rise up about 12”. I have seen this. How embarrassing if your relatives have turned up for a ride and doubly so if that brother-in-law that you dislike is also there.
So to cope with expansion, a gap is required. How much and how to achieve it? Consider the rail I am told you are using for your ground level track. I have included dimensions in the old pristine Anglo Saxon measurements as well as the foreign measurement system that you also use. Rail steel, 6m long (19’ 7” or 237”), 20mm x 10mm. Area 0.291sq” Temperature range. Assume the track was laid in the early part of the year – say 10C. I think that temperature on a hot day could go as high as 34C ? Track not protected by trees, (See the picture of the Kitsap Live Steamers – my Club) the dull iron will pick up heat quickly. Expansion of a 6m length over a 24C range would be about 1.82mm (0.072”) – say 0.08” to be on the safe side. Cut up about 2” of wire .08” size. (we have found many of those pesky wire coat hangers can be just right). Place in the joint and leave them there until the track is finished, ballasted and trimmed. If the wires are taken out too soon and then the track is moved even slightly, the gap is lost.
I think that maybe someone is saying, “Well we could put some stakes on the outside of the curve and some stakes on the sleepers to hold them down”. So what is the force in the rail to stretch 0.08”? The simple formula - F=E. A. X/L give the force ‘F’ in lbs. E is the modulus of elasticity for steel A is the area of 0.291sq” from above. X is the 0.08 gap L is the original length of 237” F is then 2947lbs or 1300kg This force per rail cannot be restrained. Hope this helps! |
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