I’ve run into a serious space problem in one corner of my layout and I’m wondering if a 3.5% grade helix would be too steep.
dp&s - Welcome to trains.com! [C):-)]
[#welcome] Welcome aboard.
I have a 3.51% grade on a 1 1/4 turn helix on my coal-originating mountain goat trail, but that’s only part of it. The usual grade is 4%, trains are very short, cars are very short and I assign LOTS of motive power - as many as three teakettle tank locos on a four car mixed train.
If you are willing to accept short trains of short cars, the only difference would be the number of turns in the helix - and, probably, the track radius. Did I mention that my radius is 350mm? The scale is 1:80, aka HOj, which is roughly half way between HO and OO.
Chuck (Modeling Central Japan in September, 1964)
Probably so.
Tight curves add to the effective grade, so your trains will act as if they are on a much steeper incline. Sadly, helixes do not abrogate the laws of physics.
Experienced modelers have found that 28" or larger radius helixes are more reliable in HO.
Gidday, I have built a 2 turn helix for HO with a 4% grade and an 18 inch radius which, with similar restraints to the ones that Chuck has already mentioned, worked OK. The helix was in a section of the layout depicting a logging short line.
BUT Cuyama is dead right, if i were to build another helix, I’d definitely go for his recommendations, however if space constrained me to an 18 inch radius again, I’d go for less of a grade and put in extra turns to gain the required height. (Needs must when the Devil pays)!
Cheers, The Bear.
If you are running steam, this is a bad idea that will cause you a lot of frustration. If you are running modern diesel, you’ll find your radius is too tight. If you are running 1st / 2nd generation diesel, just assign two locos and you will be fine.