Connecticut Valley Railroad A Branch of the New York, New Haven, and Hartford
"If you think you can do a thing or think you can't do a thing, you're right." -- Henry Ford
Carl, I think that you're worrying needlessly over this issue, and, as others have mentioned, your test data may not play note-for-note on your proposed layout.I had a sketch of a trackplan for my just-built basement, but had to abandon it when about half of the space was requisitioned for "other uses".
Rather than worry about it, I simply discarded the plan (it was truly just a sketch) and decided how much aisle space I needed. From what was left for the layout, it looked like it would be possible to double-deck part of it, so the benchwork was built fairly low.The most difficult part was determining where to locate the grades, as I wanted multi-level staging to support industrial switching. In the drawing below, the lower level tracks come from staging on two levels, with one dropping while the other rises to join it. Both then rise to enter South Cayuga. There, the line splits, with one track dropping down to cross the base of the peninsula and enter the portion shown in grey (the grey represents area which is double-decked). The other line rises at it navigates around the peninsula. Most of the grades are on curves, either wholly or partially, and most are 2.5% (equivalent to 3.3% on the 34" radius curves). The climb to the upper level is about 45' long, yielding about 20" of height, railtop-to-railtop, between levels
Still with no trackplan, I cut a bunch of curves out of two sheets of 3/4" plywood (minimum 30", but most of 'em 34" or wider) and test-fit them around the oddly shapped room. When everything looked satisfactory, I connected all of the curves with straight roadbed, and layed the track.
I normally run short trains around a dozen cars long (dictated by passing siding length), but have run much longer ones on occasion. All trains of more than 5 or 6 cars require two locomotives, and when necessary, I will add more, either pulling or pushing. (I run steam only, and use DC.)
I also run mostly "live" loads in my hoppers and gondolas, which results in some rather heavy trains. These include a tri-weekly coal train from the lowest level of staging to the highest. Train weight is 100oz. (12 hoppers and a caboose), and two modified Mikes or Consolidations will move that train as needed, but they're at their limit.
The point of all this, if you've managed to read through this far , is that I didn't really know what to expect, and simply jumped in. Build your layout as you envision it, and if your trains require more locos (or doubling or tripling the hills), just do it. I looked at my operational problems as opportunities for more modelling fun, whether as an excuse to buy more locos, or simply to increase the interest of operating the trains. I did do tests to determine the length for those coal trains, but that was after the layout was built. It prompted me to further alter those already-modified locomotives, but there is a limit to how much weight can fit into an HO scale locomotive. Twelve cars look long enough and will still fit into the passing sidings, but if I wanted those trains to be longer, I'd simply add more locos to handle them.
carl425 RE: Loco weight It seems to me that in order for the weight of the loco having to be hauled up the hill to be significant we would have to be concerned with stalling vs slipping. Granted I haven't seen everything, but I've never seen an HO scale locomotive stall.....
RE: Loco weight
It seems to me that in order for the weight of the loco having to be hauled up the hill to be significant we would have to be concerned with stalling vs slipping. Granted I haven't seen everything, but I've never seen an HO scale locomotive stall.....
In most cases, HO locos will slip before they stall, but the loco shown below (built for a friend) did stall when pulling that coal train mentioned above. It made it most of the way up the grade from the lower level to South Cayuga, but because that grade is on an elongated "S" bend (a straight section between the two curves) its pulling capacity was exceeded when the trailing cars entered the second curve while the end of the train was still within the first. While it's fitted with a large can motor, the loco alone weighs 32oz., and it appears that it was too much to allow the wheels to slip.
Even in DC operation, if multiple locos are required to move a train, all will contribute to that task, regardless of their individual speeds. It is, of course, prudent to use locos which are similar in speed, but not all prototype diesels when mu'ed together are necesssarily geared the same. As for steamers, well, that simply introduces a lot more variables to the equation. Don't worry about the tests other than as interesting experiments. Build your layout and have some fun running the trains.
Wayne
The results are not necessarily directly proportional because weight does not necessarily = drag. If all your cars have similar rolling characteristics and are free rollers then it becomes more proportional to the weight because the rolling characteristics of the cars are less of a component of the drag.
If some of your cars are brass axles in zamac sideframes, then your results will be less proportional.
The more speed matched the engines are the more the power is doubled by adding more engines. The less speed matched the engines are the less the power is doubled.
What I have done is to use the same 2x2 and 3 pieces of flex track, but then I add another 2-3 pieces tailed out on to the floor. I assemble a train of actual "typical" cars and then run the train up the grade. I then add a couple cars and try it again until the engine stalls. I found that gave me information I felt was more useful in planning. Prior to building my current layout I even fabricated one turn of a 24" radius helix and tested trains up that "helix". Lets just say that that test gave me enough info that neither my current nor my next layout will have a helix in it.
Dave H. Painted side goes up. My website : wnbranch.com
Walt and Carl, based on what seems to be the case, that the engine is the main bit of work for a typical model train that is not near the limits of its tractive effort, it would indeed seem to make sense that the locomotive ought to be required to do most of its height gain before the rest of the consist has begun to mount the grade, and to level off somewhat as the tail end of the consist begins to climb. What I don't know is what descending in the opposite direction would do for control with the locomotive at the head of the consist. Seems to me you would want to back down such a grade configuration. Goiing down it nose first would really push the locomotive by the time is was most of the way down the steepest section with all of the consist being on the grade.
-Crandell
It seems to me that in order for the weight of the loco having to be hauled up the hill to be significant we would have to be concerned with stalling vs slipping. Granted I haven't seen everything, but I've never seen an HO scale locomotive stall. If only I could get to Iraq and pick up some of that depleated uranium that the A-10's spread around. That's what we need to weigh down the locomotives.
I do find the idea of starting off with a steeper grade and then backing it off interesting.
I have the right to remain silent. By posting here I have given up that right and accept that anything I say can and will be used as evidence to critique me.
Get something like this from Micro-Mark. http://www.micromark.com/digital-pull-meter,9577.html
Measure the pull of the locomotive on the grade you want. Then measure how much force to pull cars up the same grade.
Lee
I've been watching this thread closely. I agree that it would be hard to predict results except under the exact conditions tested, so no additional comments there.
But some of the points have got me thinking.
It makes sense that the weight of the loco itself is also a factor. The heavier the loco then the better the traction (in theory) but also the more total weight that must be pulled up the hill. Also not all of the cars will actually be on the grade at once as the train enters and exits the incline.
So, could it actually help to vary the grade so that the hill is more steep at the bottom and less steep toward the top? If the loco and first cars clear the steepest part of the grade before the bulk of the cars are drawn onto the incline then it might "even out" the load. Of course going downhill this would have the opposite effect. The loco would be on the steepest downhill portion with the full length of cars on the grade.
I am sure this sort of thing is built into layouts out there whether intentional or not. Any observations?
Huntington Junction - Freelance based on the B&O and C&O in coal country before the merger... doing it my way. Now working on phase 3. - Walt
For photos and more: http://www.wkhobbies.com/model-railroad/
carl425 ... For example... If I can pull 3 10 ounce cars up 5% can I pull 10 3 oz cars up 5% and 20 3 oz cars up 2.5 %? ...
...
For example...
If I can pull 3 10 ounce cars up 5% can I pull 10 3 oz cars up 5% and 20 3 oz cars up 2.5 %? ...
No. The reason is that you have now introduced a variable confounding your intended modelling or approximation. That variable is axles, each with a pair of friction bearings. If you maintain weight and tractive effort between trials of various kinds, but alter the number of axles, you will incur differing, or varying, friction components in your calculus which you will not account for during your decision-making.
One other though occurs to me: the component of MY trains, as I run them and make them up, that causes the greatest tractive effort, is actually the locomotive itself. When my trains near a crest, they immediately speed up as the lcomotive's nose begins to level off. That tells me the locomotive hauling itself up the grade is its biggest chore. Obviously, if you keep adding cars to find the limit of traction, the greater component of effort for some locomotives will be the trailing 'tonnage'.
If you find yourself with some anxiety over performance on the basis of what you suspect will have to be the configuration of your rail system, could you do what we call 'splitting the difference', and have the lower track dropping an inch or two during its part of the run? This is mostly when there is a bridge over the lower rails, which may not be anything like what you are contemplating, but maybe that concept will help a bit in your case.
carl425 Can two loco's pull twice as much as one? Is the rolling resistance of the wheels in the train based on the number of wheels or the weight on the wheels? Do grades average out - if I have 36" of 3% and 36" of 1% is that the same as 72" of 2%?
Can two loco's pull twice as much as one? Is the rolling resistance of the wheels in the train based on the number of wheels or the weight on the wheels? Do grades average out - if I have 36" of 3% and 36" of 1% is that the same as 72" of 2%?
Yes, two locos with the same qualities/performance can pull twice as much as one of that kind. The rolling resistance is based on weight of the wheels and axles, themselves, the fit of the friction bearings, how clean they are, whether lubed or not, the weight of the frame and body on those bearings, and their numbers. That is why I suggested keeping the same consist between trials, or at least keeping a record of the various configurations of the consist as you vary something else.
Grades do vary naturally, and as I said, the locomotive hauling itself is a huge component of the effort. If you have a grade that increases in the final rising third from 2-3%, the locomotive will bog down during that portion, but once it manages to scramble over the start of the easement, you will notice it speeding up immediately.
I would place a given number of cars comprising a packet on the trial grade, and test two or three locos. Then, another packet entirely, different cars, and test the same loco. Now, if you double the locos, you can add both packets and there's your entire consist, and you'll know how much of a grade you can manage. Will that work?
A lot of my curves are 18" radius and I can run a 20 car plus train up 4% grade without issue with a Kato NW2 to a 3" height. For all that means. Take your worst engine and see what it dose.
carl425But then it also kinda feels like some folks think I'm trying to "cheat" and come up with a calculation to give me a shortcut to the knowledge.....
Gidday Carl, Cheat and Shortcut is what I thought all model railroaders do all the time to achieve their goals, and thank goodness that we all have differing goals otherwise what a boring place this would be.
Slightly off topic, but in the early 90s a young fellow rocked up to the club with a brand new Athearn BB F 7 super heavy weight and then proceeded to pull 65 cars , which was all that was available at that moment, around the then flat bottom oval (26" radius If my memory serves me). Some members then regarded that this feat should be the benchmark to judge all other locomotives by. However I had read in the MR or RMC an article about a US shortline that was still operating an F unit in the mid 80s, a typical train comprising of nine freight cars, and which during wet, icy periods had to be doubled up a particularly nasty grade, so what did the Athearn F and 65 cars actually prove to me
Have Fun and please excuse me while I go and play with my trainset.
Cheers, the Bear.
"One difference between pessimists and optimists is that while pessimists are more often right, optimists have far more fun."
All I have read so far from the respondants to your original post is well meaning conventional reasoning, some I suspect gained through bad experiences, and a desire for others not to repeat them, not to use too much grade.. In my opinion it's up to you to do what you consider necessary in your situation, but if you want endorsement to use a 5% grade then I frankly don't think you'll get it here.
Thanks Bear,
I'm inclined to agree with your interpretation of the motivation of the respondents. I just feel like I'm trying to find the best route to drive from New York to Boston and being told that the route doesn't really matter unless I have enough air in my tires.
But then it also kinda feels like some folks think I'm trying to "cheat" and come up with a calculation to give me a shortcut to the knowledge it took them many years to accumulate.
I just have a decision to make as to how steep I make this grade and I'm seeking input on that decision because I've never tried to implement as much grade as I can get away with before.
Thanks also for sharing your Sharknose experience. It and peahrens 's GP9 info are the must useful pieces of information I've gleaned from this thread.
BTW, I'm not looking for an endorsement of 5%. That's just what I tested.
carl425Why can't you offer a suggestion rather than telling me I'm not doing it right and tossing a in a whole bunch of other crap I already know.
Incidently one of the clubs portable exhibition layouts, where real estate is an issue, we have a 4%, 18 inch radius, one and 3/4 turn helix, on which my, out of the box, Bachmann Sharknose can manage 6 weighted 40' cars with plastic wheels. You can take from that what you will. Hope things work out for you.
CTValleyRRYou could make this easier by deciding HOW high you need to be at the end of your 141" run, but, ignoring the easements for a second, even at 5%, you're only going to have about 7.1 inches of vertical separation.... way more than you need for an over / under, but nowhere near what you'd need for a second level. As far as your questions go, pulling power is pulling power, and all else being equal, it wouldn't matter whether you had 3 10 oz cars or 30 1 oz cars. The problem is that all else isn't equal. First of all, a properly weighted 40' car should weigh about 4 oz. However, anything that adds friction affects your results. You've tested on straight track, but your actual layout has curves. This will affect the ability of a loco to pull cars. More wheels means more friction, so 2 80' pullman coaches with 6 axles each have more drag than 2 80' auto racks with 4 axles each. Platic wheels have more drag than metal ones, cars with electrical pickups have more drag than ones without. And so on, and so on. If you have two locos that are perfectly speed matched, their pulling power is additive, otherwise one will drag on the other. Grades do not average out. Your maximum grade will rule, and most people here will tell you thst if you have the room to use a 2.5% grade, then you shouldn't do 3%. Your problem though, is that you want to take your small test sample, do a bunch of calcs, and decide you've got it all worked out. While this will give you an approximation, because every car and loco is different, all you can do without truping it is say, "that should work".
So what is your answer? Tear the whole thing down and forget about building a layout? Why can't you offer a suggestion rather than telling me I'm not doing it right and tossing a in a whole bunch of other crap I already know. I have been doing this off and on for 40 years. I know that curves matter. I know a "properly weighted 40' car" weighs 4 oz (I just took a shortcut on the math 3, 10, 30) What I do not know is how far I can push the envelope on grade. In the past I have always followed the 2% rule.
At the end of the grade in question is the start of a 2nd lap around the upper level in a "nolix" fashion to get me to the high staging/layover/reversing loop. I will hide this track behind a "foredrop" that is painted backdrop blue to hopefully blend into the main backdrop and disappear. The higher I get this track, the less obtrusive it will be. I MUST get the 4" elevation need to go up and over. I'd like to have 12" but that obviously isn't going to happen. I want as much separation as I can get while still being confident that my trains can make it up the grade. I don't understand why you consider this an unreasonable question.
As for grade averaging, I was refering to a case where a 6' train is on 3' of 1% and 3' of 3%. It seems to me that the grade induced drag will be a product of the weight of the car and the grade that particular car is sitting on. I don't believe that any grade that is less than half the length of a train would likely be "ruling".
Wheel friction is also related to the weight on that particular wheel. If I have 30 oz on 24 wheels vs 30 oz on 80 wheels, it would seem the friction per wheel will be less. BTW, I will use only metal wheels. I just ordered 100 of the Intermountain wheelsets to replace all the plastic wheels.
trainnut1250 carl425 The consciencous of all the "maximum grade" questions seems to boil down to "you won't know until you test it for yourself". No, This is what people say when you want to go over 2% ...Actually there is a recommended standard. It is 2% or less. The problem with 2% is that it takes lots of distance to climb. Most of us have limited space. Hence the tendency to want to go with a steeper grade...And you need to test this because it might cause problems. I have done the steep grade thing and it worked for me (locos had traction tires) but I don't recommend it. My current layout is 2% or less. Your mileage may vary, Guy
carl425 The consciencous of all the "maximum grade" questions seems to boil down to "you won't know until you test it for yourself".
The consciencous of all the "maximum grade" questions seems to boil down to "you won't know until you test it for yourself".
No, This is what people say when you want to go over 2% ...Actually there is a recommended standard. It is 2% or less. The problem with 2% is that it takes lots of distance to climb. Most of us have limited space. Hence the tendency to want to go with a steeper grade...And you need to test this because it might cause problems.
I have done the steep grade thing and it worked for me (locos had traction tires) but I don't recommend it. My current layout is 2% or less.
Your mileage may vary,
Guy
peahrens Just curiosity, can you show us a laout plan?
Just curiosity, can you show us a laout plan?
I don't think it's relevant to the question so I won't post it here, but if you are really curious, PM me your email and I'll send it to you. It's in xtrackcad.
Maybe I wasn't specific enough in my original question.
I have a 24" radius 90 degree curve, 66" of straight track, then another 24" radius 90 degree curve - 141" total. I have as much space before and after the endpoints to accomodate my vertical easements (which I learned about in 1970 when I built my first layout). At the end of the 141", I need to be as high as possible to avoid scenic problems.
I won't be running single unit trains. So far I have Atlas RS11's, U30B's and GP40's; Athern SD40-2's and SD45's; Bowser C628's and A BLI SD40-2. Future acquisitions will be similar type locomotives. Assuming I always have at least 2 locomotives pulling 15-18 car trains, how can I use my test results to determine how high can I get?
If I can pull 3 10 ounce cars up 5% can I pull 10 3 oz cars up 5% and 20 3 oz cars up 2.5 %? Can two loco's pull twice as much as one? Is the rolling resistance of the wheels in the train based on the number of wheels or the weight on the wheels? Do grades average out - if I have 36" of 3% and 36" of 1% is that the same as 72" of 2%?
Paul
Modeling HO with a transition era UP bent
see stuff at: the Willoughby Line Site
The other important part of the test - how did they run DOWNHILL with that weight behind them? It's not a power issue, the cars themselves would obviously run down a 5% grade with no locomotives. It's a msoothness issue - some locos have too much play in the motor shafts so on a steep grade witht he weight of the train pushing, they tend to alternately bind up and then run free
Also as part of the measurements you really should also measure current draw to make sure you aren't overloading the motors. On a short test run there may not be any physical signs of overload, but if you built up a long helix climb at that kind of grade, it might be too much. Checking the current draw will show such things even on a short test run.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
carl425 ... So... how can I make use of this "data" to determine what grade I can get away with on the layout? I have one spot where I could all the grade I could possibly handle to get up from my upper level to an overhead staging yard. (those of us with small rooms have to think of our space in terms of cubic feet vs square feet) :)
So... how can I make use of this "data" to determine what grade I can get away with on the layout? I have one spot where I could all the grade I could possibly handle to get up from my upper level to an overhead staging yard. (those of us with small rooms have to think of our space in terms of cubic feet vs square feet) :)
Carl, this is what I would do, and solely on the basis of what you did and what your recorded for figures, your 'data'":
I would remember what the grade of my trial tracks actually was and duplicate that, or factor in curvature compensation if you intend to have such a grade on a curve. That grade, and that grade only, should be what you duplicate on your layout.
With that parallel component, you can then weigh your cars and determine how many of them, with their usual non-trial modifcations, you can trail on the grade with the same locomotive. You would want the cars in their usual state on the layout to weigh the same as the modified cars weighed on the trial grade...if that all makes sense. IOW, you must only subject the same locomotives to the same conditions to the extent possible. If you wish to experiment FROM THERE, on the layout, you can always add cars to see when the drivers start to spin.
Remember that an uphill curve will add wheel drag to the weight aspect that a loco must pull uphill. There are charts in the books that help calibrate. Suggest you consider how different locos can pull as well. My HO layout has a 2.4% grade, about 26" radius, and it limits my first loco (an Atheran GP9) to about 10 freight cars (not all optimum weighted). That's 2.5 cars per pulling axle. My 3-axle (BLI) diesels or course can pull more. I consider it acceptable (for me) as my layout is not large so my trains will seldom exceed 15 cars.
Do consider what your lightest puller will be and ask yourself whether its performance will do. In my case, I have a Bachmann 2-6-0 and it can only manage to pull 4 cars uphill. But if I designed my layout for it, I would not have (in my limited space) a track plan that would satisfy me. So my choices would be to consist two locos or just let that one pull short trains if I wanted the layout plan I have. It's one of the grandkids favorite engines and she could care less how many cars it's pulling. Basically, I knew from advice in the forum that anything over 2% would involve compromise, so the goal was to stay well less than 3%.
So, if you have lots of space to stretch your track plan to reduce grades, I'd say determine the max grade you want and the length you need to incorporate for a given rise, based on the weakest loco / train length combo you want to handle. Testing may help you calibrate, of course. But after that it's probably about compromise: shorter trains, dual locos to pull what you like, etc.
If you run slopes that steep you will need transition easments or you will have uncoupling issues at the top and bottom. You also need to be aware that curves will increase the drag and will further limit train lengths.
Dave
Lackawanna Route of the Phoebe Snow
The consciencous of all the "maximum grade" questions seems to boil down to "you won't know until you test it for yourself", so that's what I did. The best I could do was an 8 foot 2x2 with 3 pieces of flex track on it so I couldn't test any long trains. So I took 3 HO scale hoppers and filled them with .30 caliber bullets (just the projectile, not the whole cartridge). I tested with an Atlas GP40 and an Athern SD40-2. Each was able to accelerate this 30 oz. train from a dead stop up a 5% grade with only 12 volts pushing them.
So... how can I make use of this "data" to determine what grade I can get away with on the layout? I have one spot where I could use all the grade I could possibly handle to get up from my upper level to an overhead staging yard. (those of us with small rooms have to think of our space in terms of cubic feet vs square feet) :)