Transition engineering question

[selector]

It is, Chip, and I believe that you will probably get away with a 24" transition, although from 4% could be touch and go for that one loco. I stand by my suggestion earlier: try it in rough first and then be sure to duplicate those parameters in the final product. By the way, you could cut a subroadbed out of masonite, too, and use pillars beneath it all. Bending to a smooth curve would be a breeze that way.

[SpaceMouse]

Andy,

You've convinced me to cut the entire area from one piece. [:D]

I've heard it called a "Transition Grade."

[Sperandeo]

The "transistion" under discussion here is usually called a "vertical curve." I use 3/4" plywood for "ribbon roadbed"-type subgrade, and smooth vertical curves are one of the advantages that I like about plywood this thick. As far as HO scale is concerned, I don't think you can make a vertical curve that's too sharp with this stuff.

I just make sure one end of the plywood is screwed or clamped down tight and then bend it up or down to the desired grade. I find I don't really have to give a second thought to the vertical curves that form naturally.

So long,

Andy

[Anonymous]

I'm in the midst of building my latest (and best) layout and faced similar questions when constructing it.

I decided that I'd limit myself to a 1.5% per foot maxiimum grade change, and I tried to keep it to a 1% per foot change. Where did I get that number? I pulled it out of the air.

I've also heard that you should keep your vertical curves (that's what we're talking about here) to no less than a 56" radius. If you draw it out it's something like how I laid it out for myself.

Having gone from 4% to zero in 1 foot before, I can tell you that it won't work for a lot of rolling stock, and looks funny as well.

Mark in Utah

[selector]

I agree. Rough it out, Chip, and test your parameters, but make darned sure what you prove satisfactory in rough form is highly similar to what you will present to the loco(s) on the real thing. Even a 1/2 deg difference at any one point could lead to the dreaded
"AAAAARRRRGGGHHHHH!!!" heard from the train room.

Since I used 1" foam throughout, I just carved out what I thought would work, laid track temprorarily, and ran the trains over grades and their curves and turnouts. When I met a block, I planed it with a wire brush using long strokes to keep the grade even, and relaid the track. Eventually, the locos gave me the thumbs-up.

P.S. -the addition of any subroadbed material, or plaster, etc under the track will change the grade out of your favour, so err on the side of conservatism.

[Big_Boy_4005]

Well Chip, you know you have a transition problem when the pilot gets caught on the ties. [swg] You could just carve them away a little (the ties that is), but proper engineering is the better bet, and will keep you from having other problems as well.

I did some design testing when I built my helix, for both side and top clearance. I used my tallest and longest cars, and everything is perfect. Being in 3 rail O, I don't have the luxury of that nifty NMRA profile gauge. Of course that won't help with your transition question.

Mock ups are one of the best tools. Quick and dirty is all you need most of the time for a test and a straight answer.

[SpaceMouse]

Hmmm,

What I thought I was trying to avoid was derailing the front truck on my steamers.

I like the build and check approach though. BTW--on this section of track will be 26' log cars, 26' tankers, and 36' box cars. There might be an occational 50' coach.

[Big_Boy_4005]

Chip, 24" is probably close to the minimum transition. What you are trying to avoid by providing a transition, is coupler height mismatch. The longer the cars involved, the more transition is required. If you just have 40' and 50' cars, you should be able to get away with it.

Fasten a piece of plywood, longer than the transition area, flat to the benchwork on one end, and bend the other end up to the desired 4% grade. Put a piece of track on it and test it for yourself. That's the best way to find out what works.

[Anonymous]

I don't see why not. You're talking about just LEVELING the track, right? Not going back down to zero? You'd just have to make sure you did it smoothly. Understand this is my stupidness guessing here, too.

QUOTE: Originally posted by SpaceMouse

In HO scale, if you have turnout on a 4% grade, can you make a transition to a level turnout within 24"?

Anybody?

[SpaceMouse]

In HO scale, if you have turnout on a 4% grade, can you make a transition to a level turnout within 24"?

Anybody?