Help Requested - % Grade Experience

[Willow Glen Junction]

Hi all.  I'm new to model railroading and outdoor/G scale/1 Gauge.  I'm building my first layout and I need to "phone a friend" with experience (but I don't have any friends that do model railroading), hence why I'm posting.

 

I'm space constrained to about an 80' figure 8 or oval layout and I'm trying to figure out if I can get the height for an elevated crossover for that 8 or not.  My setup:

- MTH Hudson engine (ray is fixing it up for me)

- No more than 8 cars (less if long passenger cars).  figure total train length limited to 15'.  can shorten it further it its the difference between me getting that crossover or not.

- my tightest turns at the top/bottom of the figure "8" are slightly gentler than the minimum R2 MTH rates the Hudson at (R2 for MTH is slightly over 5' diameter, I will have 6' diameter 180's)

- I will be using the "post and open stringer" method to lay my roadbed (https://familygardentrains.com/primer/roadbed/ladder1.htm) and thus I figure 10" of clearance + 0.5" of track height + 1.5" of stringer height means I need to gain 12" of vertical over slightly less than 40'.  So rounding down, over 35', 12" of gain is 3.0% grade.

- H&R stainless track

 

Here are my questions:

- With only running 8 cars on an MTH hudson, how bad is a 3% average grade on a straight track?

- Does the answer change for a slightly better than R2 curve (ie will my train fail to make it up an R2 @3.0%)?

- Is it better to increase the % grade on the straighter sections and decrease on the R2?  It makes sense to me the answer is yes, but then how to figure out how to divide the % grades between straight and curve portions?

- More general question, with an MTH Hudson what fails as I increase % grade with 8 cars on an R2 curve, is it wheel slip, engine stalling, or the train derails?  Also as long as the train makes it up, what is issue or problem?  Is it just more wear on the traction tires and so if I replace them frequently problem solved, or is more serious wear happening inside the motor?

 

Googling these sorts of questions all the info seems to be based on experimentation by building and seeing what works.  I'm trying to gain some insights before building. I’m hoping someone with an MTH Hudson can give me insights on their grades, curves and train lengths. 

 

thanks in advance for your help!

 

-keith

 

 

 

[blid]

Welcome to the forum Keith

 

Maybe my layout can give you some ideas/answers: http://www.gscaletrainforum.com/index.php?/topic/810-my-elevated-semi-permanent-technical-layout/

 

I recommend the use of a track planning program to check the gradients for the different versions as you go along with your planning.

 

My gradients are 2,5% and 2.85% according to my track planning programs (WinTrack and Scarm). My tracks are LGB with R5 curves (2320 mm radii, 5,2 feet diameter).

 

blid

 

I'm gaining 12 inch too and run with the GG-1 pantographs up (and 8 MTH passenger cars). I have the Santa Fe Hudson and run it with 5 MTH passenger cars.

Edited January 3, 2019 by blid
more info

[Rayman4449]

11 hours ago, Willow Glen Junction said:

Here are my questions:

- With only running 8 cars on an MTH hudson, how bad is a 3% average grade on a straight track?   

            -   Ray:  It's going to depend on weight of the cars and rolling resistance.  MTH passenger cars for instance will have wheel power pickups that add to the drag.   I know my main ramp is about 2-2.25% grade and I can pull 4 Aristocraft Heavyweights up.  I do know there is some slippage on my layout that has unspecified higher grade.  If you run the engine slow and you have wheel slippage the engine may stall with engine wheels slipping.  If you have enough velocity it can help the engine make the grade.

- Does the answer change for a slightly better than R2 curve (ie will my train fail to make it up an R2 @3.0%)?

            - Ray:  In general it is likely going to be hard to find answers to conditions this specific but Blid did give some good feedback.  

- Is it better to increase the % grade on the straighter sections and decrease on the R2?  It makes sense to me the answer is yes, but then how to figure out how to divide the % grades between straight and curve portions?

            - Ray:  Again I think this is going to be hard to give definite answers but I would say it is better to have an overall lower grade

- More general question, with an MTH Hudson what fails as I increase % grade with 8 cars on an R2 curve, is it wheel slip, engine stalling, or the train derails?  Also as long as the train makes it up, what is issue or problem?  Is it just more wear on the traction tires and so if I replace them frequently problem solved, or is more serious wear happening inside the motor?

           - Ray:  The only point of issue is wheel slippage.  You wont stall the motor where the wheels wont turn (causing the motor to burn up).  Train wont derail.  Traction tires won't wear out even due to wheel slippage. (After 10 to 15 years they may dry out some but I have engines with tires from 2006 that are still in use and dont need to be replaced.)  Because MTH uses all metal gears in their drivetrains you won't have issues with gears wearing out for residential use.  If you run any engine on a public display where it is running 8 hours a day multiple days a week for many months on end then you may start to see gear wear.  But for what you are doing gears and motor should last you a lifetime.  Note that as you add weight and load motors will experience more heat but those motors are completely open all the way around so they are able to dissipate heat properly to avoid heat related early failure.

 

My replies in-line above

[Willow Glen Junction]

thanks guys, this is super helpful.  Sounds like I should make every effort to stretch the loops to 40' and use every inch of it for grade, which will get me 2.5%, or darn close to it.

 

Blid, thanks for sharing your layout and your grades - its a helpful reference.  I did do some sketching in SCRAM, the problem is I'm doing things backwards. I already have landscaping and I need to lay track around it.  Its hard to capture the shape of the plants in the software.  I think I need to go old school and "sketch" it out in place.  Need to think how to do this. Good to know my 12" calculation lines up with yours.

 

Ray, thanks for the details on the engine.  Sounds like there's really no way other than building it and trying it out.  At least with your details on what will fail (and not fail) I can experiment without fear of breaking the engine.

[Willow Glen Junction]

Update (treating this kinda like a blog update):

 

Took Ray's suggestion and built a test oval (40' of H&R flextrack) with "post and open stringer" roadbed method on familygardentrains.com which I could then shim the posts to different % grades to test things out.  Here is what I found:

1) An MTH Hudson with new traction tires could pull 7 MTH freight cars and 1 caboose up 2.5% grade around a 6' diameter curve no problem, even at 10 SMPH.  The grade started before the 6' diameter curve and continued around it to the end of the curve which was the crest of the "hill" which is where the downhill started.

2) After it rained (and tracks were wet), even on the straight away the Hudson had major wheel slippage at only 2.0% grade and with only 4 MTH freight cars and 1 caboose.

3) Instead if I ran just the Hudson (with tender) for a few minutes first, then added the cars there was no wheel slippage.  I didn't time it but figure 5 minutes of running.

 

So in conclusion I suppose it should have been obvious that when the rails are wet the % grade before major wheel slippage drops significantly.  this seems to be by far the biggest variable and not the % grade around a "sharp" (ie 6' diameter) curve.  I would have not guessed this before experimenting.  Since on my real layout I will only have about 40' to get the elevation for an up and over crossing (which works out to 2.5%) I have to decide how important it is to have to "dry" the track first by running just an engine vs not having an up and over.  Considering it only rains here 6 months out of the year or so, I will chose to do the up and over and deal with drying when necessary.

 

Extra credit note: when I replaced the final portion (ie the crest of the "hill") of the 6' diameter curve with an aristo 10' radius switch run through backwards at 2.50% with 7 freight cars and 1 caboose the front truck of the Hudson would derail about half the time as it ran through the switch backwards (through the curve, not the straight).  Removing just one car helped this, although I suspect with more samples (ie running longer) it would still happen.  lowering the grade through the switch seemed to help it the most however.