A grade question.

[bennyboots]

So I have decided on a HO track plan and today I picked up all the materials for my bench work. My track plan (walk in water wings) and the space in my basement I have to work with is going to require me to have trains ascending/descending a 2% grade around a 23" curve radius (I know its tight but I have no more room to work with). I was planning on using the woodland scenics foam risers which will raise the track 4" over 16'. I know this would not be a problem at all on straights but how is this going to affect the trains if the grade is almost entirely around a 23" curve. I watched some videos on youtubes of some guys pulling really long trains up curvy 2% grades with one engine. I don't know exactly the radius' of thier curves but I was really surprised it had no trouble as long as it hit the curve with some momentum. Starting from a dead stop he said wasn't possible.

Keeping in mind the trains I plan to run are modern era freight with lashed units and no longer than ~20 cars or so since my layout will not be very big. No steam and probably no passenger due to the curve restrictions.

Any info is appreciated.

 

[TrinityJayOne]

You are right in that it will be different to a straight. Not only will you have the extra resistance of the grade but also the curve. I'd strongly advise doing a lot of testing before you lay down track! If it were me I wouldn't want to be relying on momentum to make it up a grade.

 

[D&J RailRoad]

One of the things you have going for you on the grade is the length. 16' of grade with easement into and out of it means not to much on the full 2% portion. A lot of your train will still be on level track.

 

[waltr]

A curve does increase the effective Grade (I have the math equations some where). Using easements, as Ken suggests, will help. 2% and 23"R should not cause too much trouble and if a single engine can't pull the grade then do what is done in the prototype, add another engine in a lash-up or as a helper at the train end. This can make operations a bit more interesting and is easy and fun with a DCC system.

 

[CbarM]

Well this may be of some help...google CP Laggan sub. and look for the spiral tunnel area. They run 12000 ton intermodal trains up there on a 2.8% grade in a complete loop to gain elevation and they usually have 3 or 4 AC4400's draggin that up there...and the grade goes for 3 or 4 miles or more...

 

[Selector]

In the real world 1:1 scale, curves and grades have a substantial impact on the ability of the locomotive(s) to get the trailing tonnage up a grade. Not so much our models, although as the curvature tigthens and grades rise, the effect will soon close in on the effect they would have if the scale were much larger. All this to say that the lion's share of the trouble in HO is likely to come from inconsistent grade (undulationg track on the roadbed causing some driving wheels to run 'light' or even suspended on longer rigid frame steamers, for example) and generally steep grades...too steep. But that's not all; you also need vertical curves to transition from level to grade and back out of the grade again. The steeper the curve, the longer the transition if you don't want to high-end the locomotive...not high center, but high-end. That is where the outer sets of axles manage to find traction, but the central ones are doing nothing because they are barely making contact due to the sharp curvature.

So, if we accept that steeper curves need even longer transitions on either end, won't that affect what goes between the transitional ends? Why, yes it will! If you are taking up available run space to get into and out of the grade with transitions, you don't have much 'grade' left between them to get to the height differentials you want. Means, the grade part will have to be that much steeper to account for what the transitions take up getting to the right steepness or levelness. I hope that makes sense.

The best advice, already given by Trinity, is to do trials with different combinations to see what really works. It is the sure-fire way to find facts.

 

[bennyboots]

A curve does increase the effective Grade (I have the math equations some where). Using easements, as Ken suggests, will help. 2% and 23"R should not cause too much trouble and if a single engine can't pull the grade then do what is done in the prototype, add another engine in a lash-up or as a helper at the train end. This can make operations a bit more interesting and is easy and fun with a DCC system.

Yes, this was what I was planning on doing anyways. I never intended to be trying to pull a large train with only one unit. On a real railroad: 2% grade = mountain grade. I know it is a little different at 1:87 scale but it just wouldn't look right pulling big tonnage up that kind of a grade without at least two units. Maybe even 3 with a helper in the middle or at the end.

 

[bennyboots]

In the real world 1:1 scale, curves and grades have a substantial impact on the ability of the locomotive(s) to get the trailing tonnage up a grade. Not so much our models, although as the curvature tigthens and grades rise, the effect will soon close in on the effect they would have if the scale were much larger. All this to say that the lion's share of the trouble in HO is likely to come from inconsistent grade (undulationg track on the roadbed causing some driving wheels to run 'light' or even suspended on longer rigid frame steamers, for example) and generally steep grades...too steep. But that's not all; you also need vertical curves to transition from level to grade and back out of the grade again. The steeper the curve, the longer the transition if you don't want to high-end the locomotive...not high center, but high-end. That is where the outer sets of axles manage to find traction, but the central ones are doing nothing because they are barely making contact due to the sharp curvature.

So, if we accept that steeper curves need even longer transitions on either end, won't that affect what goes between the transitional ends? Why, yes it will! If you are taking up available run space to get into and out of the grade with transitions, you don't have much 'grade' left between them to get to the height differentials you want. Means, the grade part will have to be that much steeper to account for what the transitions take up getting to the right steepness or levelness. I hope that makes sense.

The best advice, already given by Trinity, is to do trials with different combinations to see what really works. It is the sure-fire way to find facts.

Thanks for the advice!