In another thread I explained the effects of grade on trains and the number of cars they can haul up a grade.
In this thread I’ll explain one way you can tell if you are hauling the most cars possible with your train.
What you will need
An accurate weight scale (like the ones used to measure letter weight)
At least 2 or 3 feet of flat level track on a flat board.
Some weights like bolts or nuts or lead weights (anything heavy)
Two or three gondolas/hoppers with similar trucks/wheels
Steps:
Add your engine with a gondolas to the level track. Progressively add weights until the engine begins to slip.
Take the gondolas/hoppers off the train and measure the weight of each one. Add it together to get a total weight. We’ll call this the “level weight”
Lift the board to a 2% incline. For 36" piece of track it should raise .72" (23/32")
Repeat step 1. Add weights till the wheels start to slip
Take the gondolas/hoppers off the train and measure the weight of each one. Add it together to get a total weight. We’ll call this the “incline weight”
Incline Weight / Level Weight should be ~50% As your number gets bigger the less efficient your trucks/wheels are. In other words 60% is less efficient than 50%. 75% could definitely use a wheel/truck upgrade.
Note 1: The smaller weights you can add, the better. This will lead to a more accurate weight and a better calculation. Lead weights work great! You can often add .25 oz or .5 oz at a time. Sand is a great option, but may require more cars.
Note 2: A small engine is actually better than a big one here. You could use that 2-6-6-6 with tra
Am I hauling the most cars I possibly can? Not very likely!
My train length was set by the prototype I model, clear back in 1964. When I designed my current layout I set siding lengths to handle that length - doubleheaded 2-8-2s, 20 4-wheel wagons.
Then I tested my motive power - not to determine maximum pulling power, but to make sure it would handle the train(s) to which it would be assigned.
The results? Only the lightest of my steam locos require doubleheading. My diesel-hydraulics and catenary motors (with one exception) can all handle way more train than I can run. The exception, a model of a locomotive with 16 driven wheels, only powers 4. It will get a second motor and gearbox when I really feel the need.
By the OP’s standards, all of my trains are grossly overpowered - but I would rather not load my locos to the max. I want reliable operation, not borderline just short of stalling operation. If this be heresy, so be it.
I’m not sure exactly what you’re driving at, DG, but you prompted me to make a few further tests.
I test all of my locomotives using a train of “stock-weighted” cars (Athearn two-bay hoppers with “live” loads, giving a weight of 8 oz. per car, plus a 4 oz. caboose). Train length is generally limited to 12 cars (regardless of weight) plus a caboose, and whatever locomotives are required to move it over a subdivision. The test track is a 2.5% grade (an “S” bend, connected by a straight section and uncompensated) which is longer than the total train length. All locos are tested, both alone and in combination with other locos. This establishes tonnage ratings for each loco. Since the test cars are unusually heavy, they translate roughly as the equivalent of two “regular” weight cars. In other words, if a loco will haul four test cars, plus that caboose, up the hill, I rate it for 8 regular cars, plus a caboose. If there’s one loaded hopper among those eight cars, there’s sufficient leeway built into the rating to allow it to still be counted as a “regular” car. For two or more loaded hoppers, though, they’re rated as two cars each, shortening the length of the example train to four “regular” cars, two “loaded” ones, plus the caboose.
For the latest round of tests, I ran a regular train of 12 loaded hoppers plus the caboose (100 oz.) from staging to the first on-line town. Here, the lead loco was dropped and the remaining engine (a modified Bachmann Consolidation) took the train to the test area. Along the way, it traversed a fairly long 1.7% uphill grade, laid out on two 34" radius curves, and connected by a length of tangent track.
Since I know from my tonnage rating chart that this loco cannot handle the entire train up the test hill by itself, I cut off the last six cars and used the 0-5-0 to add the caboose to the end of the remaining six cars. Off she went, easily cresting the grade with 52 oz. trailing.&
Put me in Chuck’s category. I’m pretty sure even my lightest loco cna pull more than 10 cars, however that is my maximum train length on my layout due maninly to the overall size of the layout and the length of my yard tracks. That’s probably fewer than the typical prototype train in my era, but then I’ve squeezed several prototype miles of track into a 10x15 room - I have a scale half mile if I’m lucky.
Sounds like a lot of work. On most layouts,I bet, the train would be chasing it’s tail. Train length is usually set by era, layout size, siding size,etc. It doesn’t matter how many cars you can pull if you don’t have the room. I have an 11x16 layout with 75 feet of mainline. The longest train is only 10 cars plus caboose. I have locos that will pull 25 cars up my 2.5% grade with no problem, But they don’t look right, to me. That’s the best part of this hobby. No one can tell you what really is right or wrong. It’s what you like that matters.
I use a method similar to Dr. Wayne. I have a large fleet of identical Athearn 50’ piggy back flats, all modified in the same ways, all weighing 4.3 oz, all with my favorite free rolling truck setup of Intermountain wheels in Kadee sprung metal trucks.
Sine these are the heaviest freight cars on the layout, how many ever of these a loco will pull, measured both on the the level and on the ruling grade (about 2%) is that locos tonage rating - simple enough.
I do keep track of those ratings in terms of oz, 30 cars x 4.3 = 129 oz rating, etc.
I find that the Kadee trucks with the Intermountain wheels provides both great tracking with a little extra weight low, and is exceptionally free rolling - equal to or better than any rigid plastic truck I have found yet.
Examples:
Bachmann 2-8-4, converted to 2-8-2 and with 5 oz of extra weight added, pulls 36, 4.3 oz cars on the level.
Bachmann 4-8-2 Heavy pulls 40, 4.3 oz cars on the level.
Bachmann 2-8-0 pulls 26 4.3 oz cars on the level.
As for train lengths, 25-35 is the typical train my layout is designed for, so it is important to know that two 4-8-2’s can make it up all the grades with their 35 cars. The layout is in a 24 x 40 room and when complete will have a 550’ long (8 scale miles) double track mainline.
On a friends layout, using similar grades and curves and with free rolling trucks, my BLI Class A has pulled over 70 cars.
This is pretty much a hobby for me. On the clubs layout there is a long straight grade of about 21/2 percent about 28 feet long. My Spectrum K4 could only pull 2 HW cars without slipping. I added a few ounces of lead and now it pulls 7 HW cars on the hill. It even can start the train on the hill if I am careful. The most dramatic is the long strings of hoppers (40) with a cabin car pulled by two 2-10-0 and one pushing. I know I can add more cars. There are some that run 80 car trains with a couple of locos up front and no helpers. Our layout is not big enough for those kinds of trains all the time.
You’ve looked at locomotive power. What about couplers? When the inexpensive plastic couplers first came out, I switched from KDs as Ithought it would be less expensive. When my train length got to about 40-45 cars; on a 2% grade another problem developed. My three Athearn BB Sd40-2 had no problems pulling the train, however my plastic couplers started to fail. (Same problem my prototype KCS had pulling long trains over the Ozarks.) I am back to 100% KDs.
All locomotives and cars have metal KD couplers.
I still run 3-4 lashups of Atheran SD40-2, but usually insert at least one unpowerd loco so that a helper unit is really needed. I have two Athearn SD50s that can pull even more.
I’m not sure what went wrong in your results in the last test. Possibly because the trucks were deforming causing additional drag/axel than normal.
I do know that driving a train around any type of curve will invalidate the results. A curve will generate additional drag that will invalidate this test. The test can be componesated for a difference in grade however. But you can no longer use 50% as your target.
Here are my restuls using 2% grade on a 6’ straight track. I must admit I used four 3-bay hoppers and lead weights with some sand thrown in.
I used a 0-6-0T as my test locomotive (the lightest in my fleet)
Using this train I hit a ratio of 55% on Kadee trucks with intermountain wheels
I then replaced the trucks with cheapo tyco plastic trucks. I hit 74% ratio.
So I’m left scratching my head where things went wrong. I’m sure you were very careful with your last test. Like you said, maybe the problem was due to the additional load on the axle like you alluded.
I’ll go back and reread your test and see if I can duplicate your results.
I’m glad you pointed this out. I was going to post a chart of the most efficient axle wheel combos. (Intermountain + Kadee, Accurail trucks + proto wheels, Accural trucks + stock wheels, TYCO.) But if there is some descrpancy in the data/method, I’m glad it’s caught now.
Actually I am pretty sure I am NOT pulling the maximum amount of cars my locos could pull but making them any longer on a 4 x 8 board would look silly IMHO.
DG, I was aware that the curves would throw a wrench into the works but it’s very difficult to find both long stretches of straight track or long stretches of level track on my layout. What I didn’t understand in your original post was the statement about incline weight / level weight showing the trucks to be less efficient as the number increases. (Math was not an especially strong subject for me.) [swg]
If my loco pulls 100oz. on level track, but only 50oz. on an incline, the IW / LW is 50%. If it pulls 100oz. on level track, but 60oz. on the incline, (IW / LW is 60%) the trucks are less efficient? [*-)]
There’s also the chance that you’ve misunderstood my test results. The main comparison of which I spoke was the loco handling 68 oz up the grade when the cars were fitted with stock trucks with plastic wheels. (The fact that the loco handled 100 oz on level track is immaterial to my situation.) I then ran the same loco up the grade using Proto trucks and wheels, with the trailing weight at a maximum of 84 oz. While this was an increase of 12 oz. over the stock trucks, it’s not enough of an improvement to justify re-fitting those cars with freer-rolling trucks, as this train is scheduled at 100 oz. due to customer requirements. The 100 oz. train on stock trucks requires doubleheaded locos, but the same train on free rolling trucks would also require two locos.
I know that there are formulae for determining the effect of grades on train length and for factoring in the additional load imposed by introducing curves, but on-the-road testing gives me easy-to-understand results which I can place on a chart, then, at a glance, know which of the locomotives available are needed to move any particular train over any particular subdivision. (This one also has to factor in train direction, as some areas are uphill or downhill, depending on direction, while others are up and
Maybe I’m missing something, but isn’t this just testing how free wheeling your trucks are?
Wouldn’t it be simpler and faster to set up a 1% grade and see if your cars will roll down it? (or 1/2% depending on your desires) And then fix/replace the ones that fail?
I do this as well, and again, in HO, the clear winner is Kadee sprung metal trucks, Intermountain wheelsets, and the lightest drop of oil in each journal. It out rolls every plastic truck I have tested, at any and every car weight of any practical use.
And cars so equiped allow locos pull more, on the level and up grades.
The reason the ratio goes up is because a greater percentage of your load is lost to friction in the wheelset.
For example with Kadee trucks and intermountain wheels, you might be able to hull 84 oz on the flat and level, and 42oz on a 2% (This is 50%)
But with Tyco trucks and plastic wheels you might be able to pull 60 oz with the same engine and 44oz on a 2% hill (74% ratio)
While your ratio is higher, you can pull less over all.
I’m still testing. I’m going to take photos and show my test method. There was some slight differences when I went with 2 cars over 4 that I used before. But nothing asoundtingly different. (like a 2-3% variance overall)
I think the entire insane rantings of my post is to help the trainman determine
Thanks for the explanation, DG, although in the example cited above, the one with the Kadee trucks pulls more on the flat but loses more on the grade, whereas the Tyco-equipped train loses less when on the grade. I know that it’s shown only for demonstration purposes, but if I needed to move a 44oz. train up that hill, the plastic trucks and wheels would be the better (cheaper) choice. [swg]
My layout is mostly hills and curves, with short stretches of straight runs tying them together. Passing siding length keeps most trains under a dozen cars, which suits the branchline nature of the layout fairly nicely. I have, however, run a 46-car train of 364 ounces up the same 2.5% grade - I ran out of hoppers, and the last few were weighted with lead blocks, as I had run out of “coal”, too. Otherwise, the train would’ve been even longer and heavier. [swg]
To comment on the original question, I am hauling all the cars that trains are allowed to on my 3 deck railroad, so for me it is not a question of the most they can pull, but can they pull the normal trains.