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Proper Grades

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Proper Grades
Posted by Anonymous on Wednesday, November 19, 2003 8:01 AM
I'm back with another "rookie" question. What are the parameters for "realistic" grades for mountain scenes and how do I "properly" calculate this? BTW: I'm working in N scale.
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Posted by BentnoseWillie on Wednesday, November 19, 2003 8:36 AM
The general rule seems to be under 2% for a mainline grade on a model railroad. That's 2 units per hundred, be they inches, centimeters, furlongs, whatever. If you have a protractor handy, 2% is around 1.15 degrees.

An easy way to gauge this in construction is to put spacers under one end of a level, which will then read "level" when your grade is at the set percentage. Make the spacer the same percentage of the level's length as the grade you want, and away you go. Example: For a 2-foot level, 2% would be around 1/2".

Gord Odegard wrote an article on making an adjustable gradient attachment for a level. "Making a gradient tool for accurately measuring grades" appeared in the August 1990 issue of MR.
B-Dubya -------------------------------------------------------------------------------- Inside every GE is an Alco trying to get out...apparently, through the exhaust stack!
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Posted by dehusman on Wednesday, November 19, 2003 9:12 AM
Grades are usually expressed in %, that is the rise per 100 units of run. For example a 1" rise in 100 inches is 1%. A quick and dirty way to calculate this is rise in inches fro every 8 feet of run (96"). So if your track gains 1 1/2 " in 8 ft its about 1 1/2%.
On the other hand if you want to go up 4" and you only want 1% grade, then you'll need about 32 ft of run.

Grades over 2% significantly degrade the pulling power of engines.

Get a 8 ft 1x4 and put track down the middle of it. Raise one end 1 in. See how many cars an engine can pull. Raise the end 2" and try it again. That will give you an idea of what kind of performance you can expect. My son has a 4x8 layout with a folded dogbone trackplan. A typical 0-6-0 or 2-6-0 can only handle 3 or 4 cars up the grades.

Dave H.

Dave H. Painted side goes up. My website : wnbranch.com

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Posted by Anonymous on Wednesday, November 19, 2003 9:33 AM
I agree, 2% is about max. I have a diesel that pulls 31+ cars on a level grade without problems. It starts spinning it's wheels with 8 to 10 on a 2% grade. It can almost pull 2 up a 5% grade. At about 10% it can't even pull itself. You can also test this with books under the legs of your current layout if it's not to big to elevate one end. FRED
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Posted by ndbprr on Wednesday, November 19, 2003 11:50 AM
2% on the real thing is a really brutal grade. Horseshoe curve is 1.85% if I remember correctly and is about 8-12 miles long. Trains are down on their hands and knees at about 5mph slugging their way up that thing with helpers front and rear. Because we don't have the mass, weight and gravity issues of the prototype we CAN not necessarily DO get by with grades steeper if needed and they will work. Generally what this means is you don't have the space for something more in the <2% range. If you need to go steeper watch the transistions into and out of them as they will be critical. They will definitely be harder on your engines too.
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Posted by Anonymous on Thursday, November 20, 2003 6:58 AM
I'm new to this too but from talking to my local hobby shops and other people I know in the hobby about 1/2" rise per foot will do just fine. i'm doing a HO layout and thats the rule of thumb I have been using and on a 36" radius circle it gives me a 4" rise, plenty enough to run more track under the curve if I want to. Iknow theres people that will probably disagree but I don't pull that much behind my engine and I'm running a stean engine pulling four flat bed cars with heavy metal catapillar constrction equipment on it and at less than 1/4 throttle it has no problem climbing it.[8)]
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Posted by DSchmitt on Thursday, November 20, 2003 2:16 PM
dehusman's advise about testing your equipment. is good. Grades can really make a diference on what a loco can handle. Curve radus is a factor too, so you might want to lay the test track with the minimum radius you expect to use on the grade.

Prototype grades generally aren't very impressive on a model RR so modelers use steeper grades for appearance as well as for the utilitarion purpose of gaining elevation.

I tried to sell my two cents worth, but no one would give me a plug nickel for it.

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Posted by Anonymous on Thursday, November 20, 2003 7:32 PM
I usually estimate how much run (horizontal length) I'll need for each 1/2" of rise when I an track planning. I work in N-scale, where engines are a little more tolerant of grades (at least until, like me, you add weight to the cars), so for a tight condition I allow a 3% grade. If X is the variable that represents the run length, then 1/2" divided by X is going to be equal to 3 divided by 100. Rearranging things according to the rules of algebra, X = 1/2" times 100 divided by 3, so X = 16.5" roughly. Knowing this, I can cut my vertical risers to 1/2" increments, and place one every 16.5 inches along the line. Or, as I'm drawing the track plan, I just note the height of the track every 16.5 inches, whatever...

Of course, to achieve a more realistic 2% or less grade you'd solve for X the same way. At 2%, X = 1/2" times 100 divided by 2, so X = 25". If you don't mind fudging it a bit, you might just say that a 3% grade is 1/2" rise in 16" run, while 2% is 1/2" in 24", and 1% is 1/2" in 48".

Why do I use 1/2" of rise? Mostly because I am in N-scale and need it finer-tuned than just even inches, but also because 16" to 24" is a decent spacing between risers (some may prefer more risers placed closer, just depends on how you build your benchwork).
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Posted by Jetrock on Thursday, November 20, 2003 8:16 PM
Sometimes extreme situations called for steeper grades--the Sacramento Northern's line to Oakland featured a 4% grade. They didn't call them "traction engines" for nothing, though. Geared logging locomotives were often called upon to go up brutal inclines of 10% or so--which is why most geared locos have a top speed somewhere around 10 MPH going flat-out due to the gearing!

I'm currently planning a mini logging layout (2.25 square feet in HOn3!) which will feature a grade of around 10-12% on a 5" radius curve. It makes me wince but with careful trackwork and a nicely weighted 0-4-0 and logging disconnects it should work fine...

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