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Model Forum / General / Railroads / April 2008Heights and clearances
In OO, what is the accepted norm for height clearances of one track over another, and what is the accepted gradient to achieve those heights please? scoot > In OO, what is the accepted norm for height clearances of one track over > another, and what is the accepted gradient to achieve those heights > please? Clearance is easy; find you tallest loco or piece of rolling stock and add say ¼ inch. Gradient is a real variable - it will depend upon so many difference factors including the length of train you wish to use, whether the gradient is on the straight or a curve, the haulage capability of your least powerful loco and so on. Certainly don't consider anything steeper than 1:30 - but on most prototype railways 1:50 is considered steep and has the potential to cause operating issues. Of course there are steeper inclines, but you're going to have to do some experimenting to see what might work for YOU! John. > In OO, what is the accepted norm for height clearances of one track over > another, and what is the accepted gradient to achieve those heights please? > > scoot The clearance between rail and underside of any obstruction should be about 2-1/2". Add the thickness of your track from underside of supporting board to top of rail to that measurement. It's typically 1/2" to 1". So the total rise is 3" or more. If you are using an overbridge, you can shave this by about 1/4". The gradient to achieve this depends on a number of factors, such as desired train length, but the recommended maximum range is 1 in 35 to 1 in 30. I would not build a steeper gradient unless absolutely necessary. With steeper gradients, train length will be much shorter. If possible, hold gradients to 1 in 50 or less. PS1: The effect of gradient on train length is substantial. If a locomotive can haul 100 wagons on the level, than it can haul 50 or fewer on 1:100, 30 or fewer on 1:50, and 20 or fewer on 1:30! In real Life, that's assuming the wagons are all braked, since coming down a hill is trickier than going up it. PS2: Design standards for track plans: When drawing up the general arrangement of your mainline, it's best to assume steeper grades and tighter curves than you actually expect to use. Then you can be sure that your general arrangement will fit the available space. The actual, detailed plan will have easier grades and wider curves, which means better operation in all respects. HTH  Signaturewolf k. > The clearance between rail and underside of any obstruction should be > about 2-1/2". Add the thickness of your track from underside of > supporting board to top of rail to that measurement. It's typically 1/2" > to 1". So the total rise is 3" or more. If you are using an overbridge, > you can shave this by about 1/4". > JT wrote: Clearance is easy; find you tallest loco or piece of rolling stock and add say ¼ inch.... Why state it clearly in about 11 words, when you can waffle the same in around 107 words? [HTH] Cheers Robt P. > > The clearance between rail and underside of any obstruction should be > > about 2-1/2". Add the thickness of your track from underside of [quoted text clipped - 11 lines] > Cheers > Robt P. The question is as straight-forward as the length of the proverbial piece of string! For example; if you are in a situation where the lines cross at right angles there's no need for a support beneath the upper track. Clearance can be: - 5mm for track height, plus 52mm for scale prototype rolling stock, plus 5mm clearance - total 62mm. (2 1/2") If the tracks are at an angle the crossing track will need a solid support base. This can be plywood or in desperate circumstances a "U" shaped metal trough. If you want to run overhead electric locos or US HO the 52mm will need to be increased considerably, perhaps another 12mm. If the crossing point is visible then you'll want to add another 15mm clearance to look prototypical. Given that every 1mm increase in height adds another 50mm in the length of each ramp or an increase in the gradient (which decreases practical train length) this is a calculation which deserves a lot of thought. Regards, Greg.P. >> The clearance between rail and underside of any obstruction should be >> about 2-1/2". Add the thickness of your track from underside of [quoted text clipped - 11 lines] > Cheers > Robt P. What JT said doesn't work. Try it. Signaturewolf k. >> The clearance between rail and underside of any obstruction should be >> about 2-1/2". Add the thickness of your track from underside of [quoted text clipped - 11 lines] > Cheers > Robt P. Robert, you are a terrible reader, and you can't count, either. I gave clearance as: -- The clearance between rail and underside of any obstruction should be about 2-1/2". -- That's 13 words. JT's as quoted by you is 18. Besides, JT's answer refers only to clearance, not to vertical rise. I could waffle on, but you're obviously a busy man, so I won't bother. Signaturewolf k. > Robert, you are a terrible reader, and you can't count, either. I gave > clearance as:.. Correct on both counts...LOL Once got 3/100 in maths exam, and 1 of those was for turning up.. Cheers Robt P. >> Robert, you are a terrible reader, and you can't count, either. I gave >> clearance as:.. [quoted text clipped - 3 lines] > Cheers > Robt P. Cheers! Signaturewolf k. > In OO, what is the accepted norm for height clearances of one track over > another, and what is the accepted gradient to achieve those heights please? I tried to keep it to 1 in 50 on my layout. I had one little bit that was slightly steeper as I thought I could get away with it and I had to re-lay the thing as my bog std. Hornby stuff couldn't handle it. (No, I didn't try the Wrenn locos... would've been interesting tho'...) -- Rod |
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