Hi!
My previous HO layout had a 2 percent grade from the main level to a lower level staging/storage area. For the locos and train combinations I used, I never had a major problem with "getting up the grade".
The new layout is now under construction and similar in design. However, I have planned on a 2 1/2 percent grade from the main level to the staging/storage area - and I am having second thoughts on this being workable for me - or not. In other words, if a given loco could pull 30 cars up a 2 percent grade, how many cars could it pull on a 2 1/2 percent grade?
I recall reading in a Kalmbach book (a long time ago) about the general effect the grades have on train length. In example, if a given loco could pull 25 cars on a flat plane, it could pull x cars on a 1 percent grade and y cars on a 2 percent grade, and z cars on a 3 percent grade. Obviously I can't locate this information and hope that you all might have it.
Thank you,
Mobilman44
ENJOY !
Living in southeast Texas, formerly modeling the "postwar" Santa Fe and Illinois Central
I'm pretty sure the chart you're referring to was in one of the John Armstrong books...if I had to guess, I'd say it's in "Track Planning for Realistic Operation". I know the affect is greater than you might expect, I wouldn't be surprised if a 2.5% grade didn't cut the engine's pulling ability by 40-50%.
Years ago the way MR checked tractive effort was to lay track on a board and they built a gizmo with a grooved wheel at the end. A tin can was attached to a string that hung over the wheel and the other end was attached to the locomotive. the can was filled with weight until the wheels slipped then the board was elevated to various grades and the weight test done again. So you can generate your curves for every engine you own. If it will haul four ounces on the level and two ounces on a 1% grade that is a 50% reduction in cars.
The table "Stix" refered to is in Track Planning for Realistic Operation, by John Armstrong (Kalmbach Books). In the Second Edition it's fig. 5-11, in the form of a graph with curves for "average" and "free-rolling" trucks. The latter are defined as rolling without a push down a .5 percent grade, easily attainable with today's acetal plastic truck frames and needle-point metal axles. The graph shows hauling capacity or train length reduced by about 66 percent on a 1 percent grade, and by 80 percent on a 2 percent grade. Armstrong's graph doesn't accont for curvature, which is also a factor,
Don Mitchell published a table of grade compensation for model curvature based on empirical research done by John Allen. It appeared in his article, "A plan for all reasons," in the July 1977 Model Railroader, pages 62-69. It also appears with the reprint of the same article in Don's book, Walkaround Model Railroad Track Plans (Kalmbach, out of print).
We haven't used a pulley and weight setup for tractive effort tests at MR for some time. For years we've used an electronic strain gauge, and we test all locomotives on the level. Our goal is to establish a standard for comparisons, not to determine what each model can do on various grades.
If you'd like to test the tractive effort of your own locomotives, see "Traction test stand - a locomotive tune-up tool," by Jeff Johnston, in the May 1995 MR, page 113. We compared Jeff's test stand to our strain gauge and found they gave comparable results.
So long,
Andy
Andy Sperandeo MODEL RAILROADER Magazine
Thank you all for the info (always good to hear from Mr. Sperandeo!).
One of my most used and treasured MR books is "Track Planning for Realistic Operation" by John Armstrong. I should have remembered that the info I recalled was in there. I have the 1976 edition and the graph is on page 51. His answer to my question is that if I could move 43 cars on the old 2 % grade, than I should move 36 cars on the 2 1/2 percent grade.
As I model the ATSF in the '40s/'50s, most of my freight and passenger trains are headed with Stewart or P2K multiple powered lashups of F, PA, and GPs. My opinion is that an ABBA (all units powered) of Stewart/Kato or Stewart/Stewart F units can pull pretty much anything. Actually, I sure wish I had the room to see exactly how many "free rolling" cars they could pull!
My concern is going to be with the BLI 4-8-4, 2-10-2, 2-10-4 and the Spectrum 2-8-0 and 2-10-0 locos, for I didn't test them on the 2 percent grade that I had previously. But hey, that's OK, for the new layout will have DCC and I could plug in a couple of helpers to get them up the grade to the main level.
Thanks again,
I have solid 3% grades with curves in the 28-50" ranges. My 4-8-4 BLI Niagara struggled to pull four Walthers heavyweights and a reefer up those grades, but some of the struggle (scrubbing of the drivers with slight spinning) I would have to attribute to my less than stellar spline surfaces and the effect this has on my track level. I added Bull Frog Snot grip compound to a pair of drivers and nearly doubled the ability of the Niagara to pull on the same grades. But it should give you an idea of what to expect for 2.5% grades if you don't have small disruptive undulations in your tracks.
I also have the BLI 2-10-4 Pennsy J1 which does much better. It is a strong puller and will tow up to 15 BLI H2a hoppers with plastic coal loads in them, plus a caboose up the grades. My PCM Y6b has yet to top out...so far it is good for 20 cars.
My encouragement to you would be to work hard, spend some thinking time, on keeping our grades down to the 2% range if you would not like to have to resort to shorter trains. At this stage of my experience and skill development, I will not contemplate another series of 3% grades; too restrictive for my tastes. Two percent...sure.
-Crandell
Purely empirical, based on my own rolling stock collection (needle-point axles, steel sideframes (!!!) will roll on track that has no discernable grade...)
Loco X will comfortably pull 12 cars on 2% uncompensated grade. The same loco will take 6 cars up 3%, and is on the ragged edge with three cars on 4%. The tractive capability curve, if extended, seems to indicate 24 cars on 1%, 48 cars on the level and 1 car on 5%. Since I don't have 48 carlengths of level track end-to-end, I have no way to test this for validity.
Loosely basing my estimate on your stated conditions, I would plan for 20 car trains on your 2.5% grades. This assumes that all of your cars have equal rolling resistance and equal weight.
Chuck (Modeling Central Japan in September, 1964 - with grades ranging from steep to hairy)
My old layout in the old house had a 2% grade on a curve going up to the ore dock (well, the ore dock never got built but the line going up to it did). At that time I had my ore cars set in groups of five (with drawbars between).
I found an Atlas GP or RS engine could push 10 cars up the grade, but not 15. The same engine could easily move 20 or 25 cars on level ground.
IIRC, my BLI 2-10-4 could push 15 cars up the grade but it was the only engine that could. I've tested it on the new layout (now using 4 car ore car sets) pulling 32 ore cars with no problem.
Thank you all for your comments - they are appreciated. As I said, the prior layout's 2 percent grade was no problem for my locos/cars in the manner I lashed them up and my typical train lengths. So in putting together the design for the new one I figured 2 1/2 percent was no big difference. Welllll, I am rethinking that now, and fortunately have a week or so before I get to that stage of construction.
The good news is that all of my railcars (used on the layout) have Intermountain wheelsets, and I typically lay pretty solid trackwork and benchwork for securing a constant grade. However, while most of the curves on the grade are 30 inch, there is one 28 1/2 inch "half circle".
I guess one solution is to lay out the 2 1/2 percent grade, do a quick wire job and test some of the locos. If problems occur, well its back to 2 percent!
Here is "Mark's rule-of-thumb" on grades for what it is worth:
Grades around 1 percent are minor and don't have much effect on train length on typical layouts.
Grades around 2 percent are moderate and have a noticeable effect. You may not be able to pull all the cars you'd like without additional locomotives
Grades around 3 percent are steep and have significant effect on train length and test the strength of your locomotives
Grades around 4 percent are very steep and challenge the pulling power of locomotives. Trains will be very short unless extra locomotives are added.
Grades around 5 percent or more are.extreme and greatly challenge the pulling power of locomotives. Don't use them but for exceptional situations such as for an industrial spur where a single car is taken to an elevated structure like a coaling dock. Keep raising the grade and eventually a locomotive won't have enough traction to go up the track itself.