Sorry gang,
I’ve been having trouble posting on replies for some reason, so i’m starting a new post here, thanks for all the info, I think I know what is wrong, my radius and grade are to tight and sudden for my double stacks to handle, the double stacks do derail AT the center of the curve, so I think I’m going to start my 2% grade right at the yard throat, my isle space at this piont is 2 1/2 feet, so my radius is 24in, If there’s any more seggestions please let me know. Thanks
Hi again!
I replied to your original post and will add a bit here… When one models the late '60s thru the present, the use of extra long and tall cars is pretty common. And of course, the longer the cars or locos, the wider radius curves are more and more necessary. And not just to get the cars to make it thru, but to make them look “real” and not toylike.
I do understand the draw for the “big trains”, even if one only has small radius trackage. But the one thing we can do is to install easements that gradually take the train into those curves, and help hold them on the track. Also, as I mentioned on my other reply, the vertical easement (from flat to grade) is just as importantant.
Hi,
in your first posting you had 12" across, so a radius of less then 5". In your second thread the radius was 35", and now it is suddenly about 24".
Have fun
Paul
I’m not sure of your actual radius - seems to vary from post to post - nor what you are actually trying to operate - 89ft double stack cars are over 12" long in HO. I’ll attack the problem in the general sense.
Stringlining (cars tipping inward or derailing to the inside) only happens on curves. It takes a pulling force that is not parallel to the car in question, which will not happen on straight track. The sharper the curve for a given car length, the more offset from centerline the pulling force is. When the offset force is greater than the resistance of the car to keep rolling on the track, the car tips in or derails. So you can reduce the offset force (wider radius for a given car length) and/or reduce the resistance for the car to roll on the track. Note that a curve on an up grade will significantly increase the resistance of a car to roll on the track because of the gravitational load of the train behind.
The LDSIG (Layout Design Special Interest Group) has a curve radius rule of thumb that states that minimum radius should be times your longest car length (measured over the couplers) for sound mechanical operation (no thought to appearance). Numerous trials and reports have found that a 2.5x minimum radius is workable in most situations - but pushing the radius this small means better trackwork, adjustments to some cars on the underb
It’s hard to see how aisle width determines your radius…
But if you are saying that there is an aisle in the center of your curve and that the aisle is 30 inches wide, then allowing for some setback from the edge, your curve is probably about 35 inches across. That is, 35 inches diameter (not radius, as you said in an earlier post). Radius is half of diameter, so that woudl mean that your radius is actually about 17 1/2".
[If, on the other hand, you are trying to tell us that your benchwork is about 30 inches deep and with space around the curve that the curve ends up being about 24" across, then your radius is 12 inches. That could be too tight for your cars, see below.]
I keep posting a diagram explaing the difference between radius and diameter in your threads. Have you noticed it?
Since you are in N scale, 17 1/2" radius would normally be barely enough – perhaps except for the abrupt grade.
Fred mentioned the
I suggest you get the long version of the ribbon rail curve gages. They are available through Walthers, etc. They fit between the rails and you can slide them around your curve and see where/if your radius has a kink, etc. 24" is usually not good enough for modern equipment, especially with super elevation and grades. I would suggest you try to get to 26"minimum, more if you have diaphragms. The NMRA has recommended practices on these things and you may want to go to their website and check out how this is all done.
http://www.nmra.org/standards/sandrp/rp-11.html
They have portions of their website to teach you how to measure, etc.
Richard
In April, the Original Poster was working In N scale.
http://cs.trains.com/TRCCS/forums/t/204778.aspx
If that is still true, 24" would be plenty of radius – even for the longest cars in N. (As you point out, not so for HO scale)
But at this point, it seems impossible to determine what his actual situation might be – he is starting new threads changing dimensions and configurations.