helix

[Anonymous]

Has anyone had any experience making and using a 31 inch or 36 inch helix for o gauge, and what spacing in inches does a person need to use between layers that will allow an engine to pull cars up the helix?

[Buckeye Riveter]

A 36" circle of track calculates to be equal to 113 inches in length. (PI x Diameter) If you wanted to get say 6" of clearence, top of track to top of track, then the grade or slope would be 5.3%.

[DLSerres]

Most of my experience for the last 40 years has been in HO, where we seldom exceeded 4% grades for long trains. But we didn't have magnetraction or traction tires on upscale models.

Now I'm returning to 0 gauge 3-rail and am contemplating a helix. Who has a successful helix out there -- and what diameter and vertical spacing is working for you??

Thanks,

[Buckeye Riveter]

Here is a table to help you with your helix design. If you want a 2% grade, and you will need 6.5" of clearence between top of track and top of track (go measure an O Gauge Tunnel Portal and you will see the clearences), you will need a circle 103 inches in diameter or close to 9 feet.
Percent
Grade

1.0% 207 inch diameter
1.5% 138 inch diameter
2.0% 103 inch diameter
2.5% 83 inch diameter
3.0% 69 inch diameter
3.5% 59 inch diameter
4.0% 52 inch diameter

A full explanation of building a helix is found in the book "Benchwork for Model Trains". It has pictures and photos to help with construction. Not too many people have done a helix because with O Gauge it taks up a considerable amount of room. Big Boy, who is on this and other Trains.com forums is building one in his basement and from the photos it is huge.

On my layout my steepest grade is 3% and on the straight sections the engines pull pretty good, but when they hit the curve where the friction increases they need more juice. BTW, do not super elevate a helix, the trains will stringline and fall over.

[daan]

Some hard evidence for pulling power. My former layout had a slope of about 5 degrees. My Lionel gp7 with traction tires lost the traction tires on the way up, so I glued them on. It was able to pull 3 postwar cars up the grade without spinning. The K-line S2 and MP-15 derailed due to the trucks having play. Solving this with spacers they managed about 6 to 8 cars depending postwar or new. My F3 didn't make the grade due to too weak powersupplies. The f3 pulls anything, as long as there is power supplied. It really depends on your motive power. First try on a setup if they can manage the grade before you build it.

[Big_Boy_4005]

A 2% grade is almost always safe. Trouble kicks in to high gear at about 4%. The formula for grade precent is units of rise per 100 units of run.

The answer to David's question has to be a simple no, if he intends to pull cars. 072 will work.

This is a 10' diameter helix with 8" spacing and a resulting grade of ~2%

[BigJim]

Keep in mind that a helix DOESN'T have to be a circle. If you have the space, make it an oval to get a longer run and a lessor grade.

[Buckeye Riveter]

Big Jim I like your thinking. One could use an oval and decorate it like a train ascending the mountains. Wish I had room.