I know that uphill grades are recommended at a maximum of 3-4%, but what is the maximum downhill grades?
I would recommend keeping all grades, UP or DOWN , in the 3-4% range…Jamie
If you have a past copy of MR, April 01 may help.
Test your engines on various down grades. You might learn you have a bearing problem that causes chatter.
Unless you intend to run your trains in one direction only on one track (a la Cajon Pass), the same consideration should be given for adverse (uphill) grades as for favorable (downhill) grades. In other words, that uphill grade will have to function as a downhill grade sometime, so the “maximums” will be identical.
On most model railroads, unless you’re modeling a specific location where the grade was steeper, such as a narrow gauge or logging raiIroad, I recommend a maximum ruling grade at or less than 3 percent. That’s a rise or fall of 3.6 inches in 10 feet. I prefer 2 percent or less.
Remember that the steeper the grade, the longer the vertical transition curves you’ll need at the top and bottom of the grade, and those vertical curves can and do eat space.
i slowly lower my grade just slowly come down to a 3-4%grade
Something to consider in downhill grades is the potential for the longer trains to accordian as a result of quick stops, especially on curves.
A place to watch those vertical transition curves is industrial sidings below the level of the main line. Because they are often short on our layouts, there isn’t much room to give them the length they need. Try to at least allow for an engine length of level running past the turnout off the main before starting the down grade. This may help prevent the pilot, or coupler trip pin from fouling the turnout as the locomotive gets up to the mian line from the siding. I hadn’t appreciated this until it happened on a module I’m building for a doorway. Short module, = shorter siding I read the remedy on this Forum [:)]
I wouldn’t go over 4%, and a more gentle grade would be better. Just because you envision a grade being “downhill only” doesn’ t preclude it from changing later on.