I want to build a layout in N scale (possibly HO9 narrow gauge, not decided which yet, which mimics a zig-zag railroad I’ve seen in Australia and climbs up a mountainside. Can anyone advise the maximum gradiant N scale locos will climb pulling only a couple/three of short wheelbase cars or wagons.
Hello mackenziebs,
The answer depends in part on the weight and type of locomotive doing the work, the weight of the cars, whether the rolling stock is equipped with free-rolling or low-friction wheelsets, and the minimum radius you’ll choose (I recommend no tighter than 9.75" for N scale).
The tractive effort (pulling power) of the locomotives you select will be the chief determining factor. Build a test track using flextrack on a straight, warp-free board. Determine the gradients using the formula “rise divided by the run.” A 1 percent grade rises 1" over 100", a 2 percent grade 2" in 100", 3 percent 3" over 100", and so on. Start with a 1 percent grade and test the pulling ability of the locomotive with the typical number of cars a train will pull. Increase the gradient by 1 percent increments until the locomotive stalls. Subtract a percent or two to account for friction imposed by curves. You’ll have a rough idea of the maximum gradident you can use.
As a rule of thumb, I wouldn’t expect to exceed 8 percent grades even with short trains. An exception would be if I were powering trains with a Shay or other geared locomotive; then I’d consider grades up to 10 percent. Most model railroads, aside from logging railroads, don’t exceed 4 percent.
Hope this helps,
Paul Schmidt
Contributing Editor
Trains.com
Mackenziebs, did you go forward with the zig-zag? I think it would be very interesting, both to do and to watch as a model in action. Marvin.