# Help with math



## Southern (Nov 17, 2008)

I have two grades to climb, both to a hight of 4.5 inches. first is 72 inches long. the second is 91. How do i figure the grade?

How many inches is an HO scale mile?


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## shaygetz (Sep 23, 2007)

An HO Mile is 66 feet.

Divide the rise by the run (length)

4.5 divided by 75" = .06 or a 6% grade.

4.5 divided by 91" = .049 or almost 5%.


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## Southern (Nov 17, 2008)

shaygetz said:


> An HO Mile is 66 feet.
> 
> Divide the rise by the run (length)
> 
> ...


Thanks for the formula for grades.

Wow that is steeper than I thought. I might have to drop the bridge. There is not much more room to leagthen the run.

how steep are the grades on prototypes? 

What is the grade on some of y'alls (usguys) layouts?


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## stationmaster (Dec 7, 2008)

Damn steep!!! Try to get 3% or less.


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## Boston&Maine (Dec 19, 2007)

Southern said:


> how steep are the grades on prototypes?


"In real-life railroading there are three classes of grades; 0.8% to 1% is light grade, 1% to 1.8% is heavy grade, and anything greater than 1.8% is mountain grade."

From: http://modeltrains.about.com/od/layoutconstruction/tp/track_grades.htm

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Like StationMaster said though, you can get up to a 3% grade on a model train set without there being problems and without it looking unrealistic...

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Southern said:


> Wow that is steeper than I thought. I might have to drop the bridge. There is not much more room to leagthen the run.


If you do not drop the bridge you would need to have a run of 150 inches... If you do drop the bridge it would need to be about 2.15 inches high to make your 72 inch run a 3% grade... Pick your poison, LOL...


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## stationmaster (Dec 7, 2008)

Boston&Maine said:


> "In real-life railroading there are three classes of grades; 0.8% to 1% is light grade, 1% to 1.8% is heavy grade, and anything greater than 1.8% is mountain grade."
> 
> From: http://modeltrains.about.com/od/layoutconstruction/tp/track_grades.htm
> 
> ...


When I did my layout, I measured my tallest engine/car and added 1/8"-3/16" for clearance to the bottom of the bridges. It looks authentic and I can run anything I have on the layout.


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## T-Man (May 16, 2008)

Can you even notice a 3 degree difference or or we all getting to be rivet counters?:sly:


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## stationmaster (Dec 7, 2008)

T-Man said:


> Can you even notice a 3 degree difference or or we all getting to be rivet counters?:sly:


Well, uh, yeh. Especially when a loco can't pull 8 cars up the hill!! 

Manageable grades is not being a rivet counter, I wouldn't think. Unless you like running short trains. I don't consider myself a "rivet counter" at all, but I do like having consists of 15-30 cars vs. 8.

I've got some pretty good engines, but a 6% grade would definitely be a test that I don't think some could pass. I would definitely see the amp meter go to the right with the increase draw. That can't be good on them.


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## T-Man (May 16, 2008)

That makes sense! I see the point now. Thanks


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## shaygetz (Sep 23, 2007)

The Western Maryland had a 9% grade between Chaffe, WV and Vindex, MD.


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## stationmaster (Dec 7, 2008)

shaygetz said:


> The Western Maryland had a 9% grade between Chaffe, WV and Vindex, MD.


And they double, triple or even quadruple head those consists and add a "pusher" or two. That would be neat on a set up, but not real practical. I think that they may even break that consist and make two trips up the hill.

I've seen videos where they triple head, and add an engine or two in the middle, and add a "pusher(s)". That is some steep hill. I don't think that I would even like to walk it. It would be like walking on a 9/12 roof(12/12 is 45 degrees).


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