Hi:
I’m looking at incorporating a helper district on my layout. My trains will be no more than five feet long and the grade will be around 10-11 feet long. My locomotives will be steam engines from 4-6-2 Pacifics to 4-8-8-4 bigboys. I’m planning on using Woodland Scenics risers.
What grade do I buy? The 2% riser is 16 feet long, 3% is 12, and the 4% is 8 feet long!
Which is not enough and which is too much?
Thanks.
Sheldon
I haven’t used iot myself but I would figure you use as much of the grade risers as you need to get the height and length you need and then stop there. Somebody will tell you if that’s wrong.
I do not know. LION never got good grades in math.
Who cares what the grade % is; One track is here… The other track is there… you gotta connect them, and the locomotive has got to do it. If it cannot then you have to move the tracks.
But with THAT locomotive I’d want the lowest grade possible. You will need to ease the transitions top and bottom, and since it is a big locomotive, you will want to be pulling a big train.
Keep the grade as gentle as you can.
ROAR
The critical numbers are how high are you trying to go and how far you have to get there.
At 2% in 10-11 ft you will climb about 2.5 inches.
At 3% in 10-11 ft you will climb about 3.6 inches.
At 4% in 10-11 ft you will climb about 4.8 inches (if you can get your trains up that steep of a grade).
The length you mentioned is the amount of material in the package. If ther is 16 ft of material in the package and you only have a 10 ft grade then you won’t use 6 ft of material. If there is 8 ft of 4% material in the package and you want a 10 ft long grade then you have to buy another package of material to get the other 2 ft.
Normally its suggested that you keep grades involving steam engines at 2% or less.
Should of made myself a little clearer. In asking how much is not enough or too much, I meant the % of grade not the length of riser! I’m trying to make the grade look realistic without having my engine die trying to do it even with helpers. Your suggestion of 2% for steamers is well noted.
Thanks
Sheldon
Sheldon,
Since you want to run steam engines(the models are notoriously bad at climbing grades for the most part), I would not go more that 2%. You will be surprised how fast the capability of an engine decreases as the grade increases. I would not be surprised if that 4-6-2 will only handle 5 passenger cars up a 2 % grade. That’s what helpers are for!
Jim
Thanks Jim!
You have to think about the capability of the engines first, but also how and where you want to run them.
For the space you have to assign to the grade, does the upper level track have to cross over another track? If so, you need clearance between the top of the rolling stock running below and whatever bridge or structure is supporting the rails under which that lower track runs. Clearance is a problem.
Secondly, if you don’t have to worry about overhead clearance, do you have the room for a reasonable grade for your head-end power, whatever it might be on a given day, to get up the grade that has proper/reasonable vertical curves on either end? The grade cannot start abruptly, nor can it end abruptly, especially on a curve! You need gradual onsets so that the locos keep traction on the rails (it’s all they’ve got is the slippery rails under them, so don’t make any wheels hang up off the rails with a short, sharp transition curve into the grade or out of it at the top). Now that you have taken up some of that distance on either end of the grade for the transitions, what’s left to gain all that altitude you designed into your track plan? It won’t be the 12 feet you thought you had, but more like 9.5 feet. It gets worse the higher you have to make what’s left of the grade climb, too. The steeper the grade, the more transition into and out of it you’ll have to afford the locomotives for that all-important grip on the rails, but also for the sake of couplers that might not all be exactly at the same heights as the ones to which they are mated.
It’s sometimes a touchy hobby we are in, but it can all be accomplished if we are prepared to do a little give and take, and to rethink some ideas. But grades really restrict us, as an example of factors that define how we’'ll get to enjoy our layouts. There’s a lot of physics and engineering to consider about grades.
Crandell
What Jim said!
Everyone here has hit on solid information regarding grades.
As noted earlier, model steamers are notoriously bad climbers out of the box. Some reference for you, I have 3% grades. The worst climbers I have are my Bachmann 4-8-4’s. Maybe it’s the large drivers (more on that in a moment), but I finally got it to pull halfway decent by shoving 6 ounces of weight in every nook and cranny I could. My best puller is my Athearn 4-6-6-4, heavy, smaller drivers, and two traction rings, out-of-the-box great puller. Next is an IHC 2-8-2 Mikado, again, smaller drivers, a fair amount of weight for its size. I’ve still added 5 ounces to it and it’s very respectable. My Rivarossi 4-6-2 Pacific handled 6 Athearn heavyweight coaches after adding a small amount of weight (1 1/2? ounces), again, larger drivers. Though it did not spin, it liked them much better after pulling the weights out of the coaches- speed is more consistent between up and down grade.
Something no one mentioned yet is wheel and wheel/truck interface quality. Your grade pulling ability will be greatly enhanced by two things: tuning the trucks using a Reebox or MicroMark tuner, and running metal wheels. I read enough pro’s in the forum’s regarding both that I jumped, bought a tuner, and began changing to metal wheels. 99% of my rolling stock on layout currently is running Intermountain wheels and all trucks are tuned (waiting for more $$$ to do the heavyweights). What a difference!
Finally, I mentioned driver size. It would seem smaller drivered loco’s pull better. I’m no physics engineer, but I think it has something to do with the weight per contact surface area. Though they are round, to a minute degree, I believe a larger driver will have a slightly larger contact area. If two loco’s, one small and the other large drivered, weigh the same, the larger wheel will have its weight spread over a larger area, thereby creating a softer “footprint” in the same amoun
Makes alot of sense to me!
Thanks Duane.
Sheldon
Good information on the practical reality of grades, Duane. However, there is physics involved with driver diameter. It has nothing to do with contact area. It’s all about Torque. Torque is the product of the driver radius times the force produced. T=rF. A given locomotive will have an available torque. If the driver radius is large, the resulting force is small. Conversely, for the same torque with a smaller radius, the force will be larger. That’s why the smaller driver locomotives have more pulling power - but they don’t have the speed of a larger driver engine. An 0-6-0 switcher can pull as large a load as a 2-8-2, but only at low speeds. Passenger engines generally didn’t have to pull as much of a load as a freight engine so they had larger diameter drivers for more speed. In mountainous territory it was always a trade off between speed, tonnage rating and grades.
Next step for me (as in maybe get started tonight!) is to move my controller to the new layout, lay down some track on the graded section, and see what my locos can do. My planned maximum grade for the finished layout is 2% but that is based on recommendations here, not personal experience. Since the inclined “cookies” are not permanently attached yet they can be easily adjusted up/down just to see what happens. I’ve got about 17’ of the inclined sub-roadbed in place with some straight sections and some 30" radius curves so should be plenty enough for some good testing.
My locos are a Bachman 2-6-6-2 articulated steam engine and Alco FA2, FB2 diesels which I can run independently or in a construct. My guess is that the Alco construct should pull very well. And I am thinking that the articulated running gear on the big steamer will give it much better pulling power than a 2-8-2, hopefully as good as one of the diesels. I only have 10 cars to pull but three are 65’ passenger cars. Should be interesting to see what happens.
Good info Ray. I fully understand the torque issue regarding driver size and relating it to overall speed. I’m merely observing that with model loco’s, mine anyway, the larger drivered spin way earlier, stalling the consist on the grade, than the smaller drivers. Whatever the reason, in our model world, swap the large drivered loco out with small, couple up more freight and steam away!
I use helpers in the form of 0-8-0 Rivarossi’s, which have smaller drivers than the Mike, so my speed is kept down- running appropriate road speed for the smallest drivered or limited capability loco(s). My Pacific is dedicated to a passenger consist, the Challenger pulls double duty depending on mood, and the 4-8-4’s spend most of their time in the boxes.
Happy RR’ing! Duane
Actually, in both prototype and model, any torque beyond that which starts the drivers spinning is unusable.
In the model, putting in a motor with enough torque to spin the drivers is a safety valve for the motor. If the drivers spin, the motor doesn’t stall and doesn’t cook itself.
The limitations on traction (pulling power where applied torque is limited by spinning drivers) comes from the weight on the driving wheels. For optimal traction, the weight has to be evenly applied to all driving wheels. Otherwise, the most lightly loaded driving wheel starts to spin first, which starts a chain reaction to spin all the drivers.
The prototype achieves equal loading through equalization - which keeps each driver properly contacting the rail head with consistent pressure. When properly calibrated, model engines with sprung drivers achieve equalization. Long rigid frames in model engines (unsprung large driver 4-8-4s) are the most like
I needed a 4 1/2% grade to make an upper yard, I have no proublem pulling 10 plus cars with a good quality steamer with small drivers, and it looks fine also as I put a meander into it. Now in real life this would not work. I also have a 6% downgrade only (but sometimes I like to try and go up, just to see the wheels spin).
One way to increase clearance without increasing grade is to lower the lower track.
when this is possible!
Hi Canadian Big Boy,
you have been talking about the length and the steepness of a grade. No word so far, though it was asked by one of the posters, about the rise (or clearance) you want to achieve nor about the extra length required by vertical easements.
Curves are adding drag too. A formula used by John Allen for HO is “added drag”= 32/R. When you have a 3% grade on a curved section with a 24" radius the added drag = 32/24 = 1,33%. The grade compensated for curves then becomes 4,33%. Are your engines up to those grades? Some experimenting might be needed.
Smile
Paul
I have no clearance issues or a certain rise to attain.
I have a 24 foot straight area along a wall. I’m planning on having an alternate route to my main line, and going in one direction I want to have a helper district where there will be a grade for around 10-11 feet long with some slight curves to break up the straight line. After the summit is reached I plan on a long easy grade down the other side which would not be any more than 1-2%. I realize that the down grade will be twice as long but thats ok.
I’m trying to get advice on how steep the grade should be for a dedicated helper district, meaning that no train will try to go that way without a helper. In John Armstrong’s book on Realistic Operation, he claims a grade of 4% is needed.
Thanks
Sheldon
I believe we have suggested that it must be derived empirically…by you using your locmotives. We don’t know how well you lay track, what track you’ll use, which models you’ll use, how long & heavy the trailing tonnage is that you hope to run, etc, etc. So, once again, do trails. Mock it up and see how you do. At some point, a single locomotive pulling the trailing ‘tonnage’ that you feel should be a typical timetabled train in that district, as it were, will not do it on its own up the grade. That would be where you would want a helper.
The real truth is, even with a mere 1.5% grade, and not a whopping 4%, your lone head-end locomotive might make good use of a helper. That’s the way it works in the real world, and you can just decide to lay shallow grades so that some single engines CAN lift their trains and others will need helpers.