Yard Master & Research
One finds info in the strangest places. With all the hoopla about grades, pull,inclines, I robbed this off You tube for your enjoyment. Seven cars and a 6 inch climb over 360 degrees. Enjoy
A helix is used to change track levels using the lowest amount of table space. This one rises 6 inches in each 54 inch circle for a grade of about 3.5 percent. This same 6 inch rise would take 171 inches, or 14 ft of straight track. In this case, the helix takes a train from table top level, to just above door level, which is a total of about 28 inches. See my more recent videos for more details. More importantly, my wife saw one in HO, and specified that I had to have one on my layout
Mine is 42" in, and 54" out, with 6" layers(top of track to top of track, so clearence is app 4 3/4 inches. The Polar Express is pulling all it can on the outside. It will not pull up the same cars on the inside. If you let me know the type and how many you want to pull up yours, I can try it on my 0-42 loop over the holidays.
Advice: 1)If using 1/2 inch ply, use 4 ply instead of 3 ply. 3 ply flexes too much. 2)Don't forget the transistion grade top and bottom. Can be straight tracks