# Small over under loop?



## tparone (Jan 2, 2008)

Hi, I found some extra track, 5 foot diameter and enough sraigh to make a loop about 15 foot end to end. Does any one have any experience with a over under layout with such small dimensions? Curious if the grade to climb 1 foot and then come back down will make it prohibitive grade is well above 3 percent, but curious if it has bee accomplished successfully.

thanks
tony


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## Manco (Jan 5, 2009)

I did a simple over under figure 8 on my first layout. With 12' radius (not diameter) curves, including 16' radius easements and about 12' straights, I would say the grade was pretty steep. Can't tell you the exact grade but over easily over 2%. If you're only running 3-4 car trains though, you can get away with a lot.


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## Dan Pierce (Jan 2, 2008)

Depends on the engine. 

I would not run a light engine like the LGB FRR engines on a steep grade as these engines were meant to pull 2-3 cars at best on the level. 

A more robust engine and those with traction tires would do much better. 

And the engine must be capable of running on the smaller diameter which leaves out 3 axle engines by USA and Aristocraft. 

LGB has a powered tender that goes with their 2 axle steam engines and would this pair would do well on small curves and 2-3 per cent grades.


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## vsmith (Jan 2, 2008)

This was my indoor layout, I had about 12-13 linear feet of track as run up on each side to the overpass, this was a 4+ % grade, and was a very steep haul for most my engines but all my trains were short so it wasnt a problem but you can see how much real estate even this small over/under required. It depends on what your planning to run (long trains vs short) and what your long term goals are. IOWs dont do something like this if you ever want to run live steam for example. How big an area do you have to work with?


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## tparone (Jan 2, 2008)

Thaanks for the feedback! THe length of the whole payout is about 15 - 16 feet, so it seems the over under would be way to steep, even for my little trains ( hlw might mack and hopefully another small steam engine. You can see from my layout the space i wanted to fill on the inside of the current 8 foot diameter loop. 

Ill just put in a curvy dogbone shape and think about raising it up a bit with ladder roadbed so I can use some trestles and a bridge. thanks!


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## vsmith (Jan 2, 2008)

FYI - my layout above was 19'6" long x 10'0" wide and used R1 curves, 16' w/ R2 would be tight but instead of a figure 8 you did a circular over under it might work.


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## pdk (Jan 2, 2008)

There is no such thing as a small over/under loop, unfortunately. To provide adequate clearance you need a lot of room, otherwise the approach becomes so steep that (never mind whether the loco can actually make it up) it just looks weird, in my experience.


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