Proper Multi-Level Separation

[BobZ]

I'm just getting into G using Bachmann metal track. I come up with a layout that will have 2 or 3 track levels, running at least 2 trains. What is the proper distance between levels? I will be running Big Hauler type of equipment to start. Also, what is the max rise percentage and gradient degree? ie: 4" rise in 72" of track. My calc indicates 5.66% rise which equates to a little over 3 degrees gradient. Am I even close??   

[BobZ]

I think I found my answer on a post several pages back. They recommended 10" clearance from top of rail to lowest overhead. Sounds ok to me.

[Loco Bill Canelos]

Simply stated the heavier your grade the less your locomotive will be able to pull up grade. do as best you can to keep the grades between your levels as low as absolutely possible.  On the early narrow gauge rr's there were times when certain locomotives could only pull one car up a given  grade.  I my 65 years of model railroading the thing I most regretted was having grades that were too steep!! 

Have fun and keep those grades low!

Bill

[Kevin Strong]

A general rule of thumb is to keep grades at 4% or less at all costs. You start getting steeper than that, and you start running into troubles in terms of the trains you can pull up, and the trains you can run down. You're not going to get "runaway" trains, but what happens with locos on steep grades is that the weight of the train pushes against the locomotive, and you get "surging." That's where the weight of the loco wanting to push the train down the grade comes into conflict with the motor in the loco wanting to pull the train. It's hard to explain exactly what's going on, but you begin to notice it on 4% and steeper grades. Keep things milder, and the trains will run smoother up and downgrade.

Later,

K

[BobZ]

Kevin, when you say 4 deg max you are referring to the actual angle? My example of a 4" rise in a 72" run (a little over 3 deg angle) would be ok?
Thanks
Bob

[Loco Bill Canelos]

Bob,

it is percent grade rather than degrees.   So 4 percent would be equal to 4 inches in every 100 inches.  In my personal opinion 4 inches in 72 inches would not be good if it can possibly be avoided, especially if the grade were on a curve.  Try this set up 100 inches of straight track and raise one end 4 inches.  Run your locomotive up pulling two cars, then raise it another inch to five and see what the difference is, or measure out 72 inches and raise it four inches at that mark and see what happens.  This will give you an idea of exactly what you will run into if you build the layout using the different grades.  If curves are involved the difficulty involved gets greater.

Hope this helps.

Bill

[mickeykelley]

Just out of curiosity, what were the real world grades mentioned above that they encounter that resulted in only being able to pull one car.  Seems that would have drastically hurt profitability on a line.

[Loco Bill Canelos]

Mickey,

It had as much to do with the tractive effort of the locomotive as it did with the grade, a light 4-4-0 on a 5% grade might pull one car while a heavy 2-6-2 might pull four depending on the cargo or if they are empties.  That is why so many narrow gauge pictures show two locomotives on the front of the train and a third pushing and yet the train has 10 or 12 cars.

Bill

[Kevin Strong]

A Baldwin catalog for early narrow gauge railroads that I have in my collection lists tonnage for each locomotive on the level, and at various grades up to 2%. From flat to just under 0.4% (20' per mile), the tonnage drops by more than half. So a loco rated at 1200 tons on the level falls to 560 tons on a 20' per mile grade. At nearly 2% (100' per mile), that same loco is limited to 155 tons. These are c. 1877 locos, which when run with c. 1877 rolling stock would have meant about 10 - 15 cars per train on a 2% grade. As locomotives increased in size, so did the size (and capacity) of freight equipment, so a "modern" steam locomotive would still only be able to pull 10 - 15 or so cars over that same grade because the cars weighed significantly more than their smaller predecessors.

A 2% grade is very typical of grades on narrow gauge lines; many were even steeper--closer to 3% with some railroads having as much as 4% grades in certain places. It's not unusual to have even a fairly large locomotive only be able to handle a small handful of cars up a 4% grade. On the Cumbres & Toltec, they frequently doublehead K-36s to pull the passenger trains up from Chama to the top of Cumbres Pass; and those are some of the most powerful narrow gauge locos built, pulling 12 - 15 car passenger trains.

Later,

K

[Doneldon]

Bob-

Your 4-inch rise in 72 inches is just a whisker over 5.5%. That's really kind of outrageous in the world of locomotives. I would dare to say that probably half of all locomotives would be unable to pull themselves alone up such a grade and very few could haul any cars. Well, the old Lionel MagneTraction, which could practically run upside down across the ceiling could handle it, but that's about all. I strongly urge you to do whatever It takes to flatten that grade. Believe me, you will get sick of the problems it will cause real fast. And it's always to prevent problems in advance than it is to fix them after the layout is built.
                                                                                                  -- D

[Dave]

Bob, I have a couple of 3% grades and my Annie just manages to pull 4 coaches up, on a good day. I wouldnt reccomend any grades more than 3%, unless you are wanting to double head. It also puts a lot of stress on the drive train which will result in premature wear in the gearbox.

              Dave
               New Zealand