Grade Transition

[Anonymous]

Reference image: http://members.cox.net/dbhuff/images/h&h03b.gif

I will have (layout still under construction) a grade change from 2% to 5% at one point on my HO layout. My layout has a 2%, 20" radius helix for 240° going into a double curved turnout. The inside TO curve transitions to 2% up, this transition is about 2' in length then climbs for about 3' before leveling off . The outside of the double curve TO transitions to 5% down. This grade transition is about 1' in length and the 5% grade runs about 3' then goes back to 2% where the transition is about 2' or more. This short 1' grade transition is needed to "duck under" another track to get to the west-to-east return loop.

Once completed, does anyone know if this transition is to short and will give me any problems or should I try to alter this somehow before I lay the track? I will be using Kadee couplers on both freight and passenger cars - era early '50's.

Is there a recommended length for grade transition? I've looked on NMRA but can't find a reference.

[Big_Boy_4005]

Any "verticle curve" needs to have a gentle transition for smooth operation, just like "horizontal curves". The key is to keep your cars from uncoupling. Make sure that all of your cars have their couplers at the proper height. Use the Kadee height guage.

[nfmisso]

QUOTE: Originally posted by Snake

if this transition is to short and will give me any problems or should I try to alter this somehow before I lay the track?

Yes, Yes and DEFINITELY YES.

Make two of these:
Take a 12" ruler, glue two 1" long 1/4" diamter dowels to it at the 2½" and 9½" lines.

Your transistion is too short if these two will not stay "coupled"

[Anonymous]

Big_Boy_4005, Good suggestion, and yes I have one. I don't know how some of these guys put kadees on without one. [:)]

nfmisso, As a Mechancial Design Engineer I am sure you know what you're talking about and it sounds like a great way to test grade transitions. But a farmboy like me needs to make sure I understand what you're saying. So I must ask,

1. I glue the two 1"x1/4" cross ways on the ruler?
2. Should the ruler be centered at 1/2" or glue it off center so the dowel is longer on one side?
3. Once glued, I then use one to pull the other to simulate one car pulling another?
And I guess the way this works is I would hold the front of the pulling ruler down and if the pulling ruler high centers it will ride up over the pulled rulers dowel [^]

[Anonymous]

Transitionss have caused me grief and after about a year of seeing cars go for a spill I finally got on my knees, (Not to pray ) but rather get a bird's eye view of what was causing the problem, Firstly I was using foam risers and cork road bed to ensure my grades were consistant, what I didn't think of when I laid the track was the track joint corresponded with riser/base interface, in other words there was not gradual transition just a "Pot Hole". Secondly, the there was a No. 6 Turnout on the grade, turns out it was a tad "hogged". I have spent this past week removing these problems from the layout and to ensure a really nice transition I took an aluminum yard stick (good flex and pliable) and laid it (on the flat) at the base of the gradient at one end and on the upper part of the gradient at the other end. the yard stick has a nice gentle bow in it and all you have to do is make sure the track under it is in contact with it along it's full length. the track will require shims. And yes there is better ways of doing this. But I'm working on a table top. Maybe next time on the next lay out I'll get it right!

[nfmisso]

QUOTE: Originally posted by Snake

1. I glue the two 1"x1/4" cross ways on the ruler?
2. Should the ruler be centered at 1/2" or glue it off center so the dowel is longer on one side?
3. Once glued, I then use one to pull the other to simulate one car pulling another?
And I guess the way this works is I would hold the front of the pulling ruler down and if the pulling ruler high centers it will ride up over the pulled rulers dowel [^]

1. yes
2. whatever works for you.
3. pushing, or you could mount Kadees on one end of each, and pull.

The dowels simulate the trucks. This is just a visual "qucik & dirty" method.

I like Fergie's suggestion better. A bent beam gives near perfect easement geometry, which is one of the reasons "cookie cutter" and "spline" sub road beds are so effective.

[Anonymous]

Thanks Nigel

In retrospect I wish I had gone with "spline" unfortunately I'm commited or in my wife's words I should be.

[Anonymous]

Thanks for the help! My layout is Spline on Open Grid. The sub-roadbed is 1/2" plywood on risers.

Here's a some pics I took the few first weeks of building. I haven't up dated (added) any photos for awhile.
http://members.cox.net/dbhuff/dsrr/