I am a bit upset with the DRAWBAR ratings that all the testers use to rate the Pulling Power of their products. I am moving cars from one yard to another and put together a 15 car mixed train. Mixed in that some have metal wheels and the latest trucks and others are out of the box Bachman or just blue box and roundhouse kits with whatever came with the cars.
Route is .1% then up 1.6% and then down 2.1% then reverse loop and back up the 2.1% to the other town. Simple.
Results where not that simple:
Engine one: New Walthers Y3a Sound and no traction tires. Never made it up the 1.6% at all.
Engine Two AHM 1970’s Big Boy (traction tires replaced with new driver and wheel set (this is the one that hit the floor about 6 months ago) Pulled the load with no problems or anything in both directions. Set the throttle and it just did its thing.
Engine #3 BLI AC4. made it but really had to turn up the power to make the 2.1% climb.
I was going to try the Mike or Hudson’s but looks like I have to do all my freight cars so that I can move as many cars as the ratings say.
We have no trackage that is level it is all up or down except for the yards and sidings. I am sure if one of the legs was flat and you got up a head of steam you could make the climb but thought that only 15 freight cars would be no big deal.
I’m not 100% sure what you’re asking, but based on the subject line here’s my thoughts on drawbar ratings.
What’s the better alternative?
The drawbar rating itself is what it is… “6.2 oz.” or whatever. You can discuss methodology (is it pull at wheel slip? Pull at stall? What’s the method to get it), but if you keep it apples-apples, you get comparative numbers.
Now, usually you see it translated into “X cars on straight level track”…That’s where maybe the problem lies? Certainly I’ll agree that a theoretical number of cars pulled based on all of them being free rolling, properly NMRA weighted cars on dead flat straight track, and the real-world experience of what motley mix of cars it’ll pull on what grades are entirely different.
And yet, given your own experience, don’t you think drawbar numbers on the Big Boy would have been quite high, moderate on the BLI and suggesting weak pulling on the Y3A? While the reviews “X cars on flat level track” and your “15 cars on varying grades” might not jive, the drawbar measurement probably would have suggested what you would experience.
And as to the cars used… How is a reviewer to project the proportion of metal to plastic wheelsets, nicely rolling to sticky trucks, various weights and materials in any reasonable way? Your 15 cars might bear very little relation to my 22 cars, except that if you hook each of them up to a scale, each will require “Y” ounces of pull to move and keep going.
I wonder if you were able to measure the ounces of pull required to move your 15 cars up your grades, and compared it to the ounces of drawbar pull available from each loco, if you wouldn’t find it jives quite nicely…
I’m certainly open to a “better” and/or more “real world” metric to assess loco pulling power comparatively: I just can’t think of any that fit that description…
THta is what I was trying to ask. I guess a trigger pull scale or a fish scale could be used to get the pull weight required to move this pile of junk. I guess that when you look at it a car that weighs in at 4.6 oz on a digital scale will require “X” power to move on a level plane BUT when you put in a 2.1% grade then the 4.6 oz car now has a value of 6.6 or 7.6 considering the type of wheels and such.
All I would like to see is that just once they would say we used X number of cars that where made by mfg “Y” and this is what it did.
They use the ‘fish scale’ method, they don’t take X number of cars and hook them up and try to pull them. Plus that 2.1% grade is on a curve, so the effective grade is goignt o be somewhat higher due to the friction on the curves. What radius is that loop? On the larger locos this can also have a detrimental effect - regardles if the manufacturer says the loco can take a 18" radius curve, there usually are issues. Even with 32" radius curves I can see how the curve affects my T-1 4-8-4. Without BEMF I’m sure it would slow - and that little bit of binding will reduce pulling power as well.
Now - how did they fail to make the grade? Slip? Or stall out? The BLI - does this have the upgrade chip in it with the better BEMF and so forth? If that made it but required additional throttle - that’s probably behaving as intended, more like a real loco. If it wasn’t spinning its wheels, it may need to be adjusted to somewhat lessen the effects of grades so you don’t have to open the throttle as much. The P2K is probably poorly balanced or just too light. That many wheels should be able to pull that load, unles you have one of those cars in there that rolls like the brakes are on - P2K cabooses anyone?
Even if all of your cars weighed ‘exactly’ the same, poor rolling trucks/wheelsets on one car will make it a ‘sled’ conpared to a free rolling car. All of my freight cars are weighted to NMRA weight, and I use metal wheelsets in truck sideframes that have ben reamed out with the ‘Tool’ from Micro-Mark. The metal wheelsets/reamed trucks did not offset the additional weight, but the cars perform so much better with the added ‘heft’. My BLI USRA Heavy 2-8-2, will pull at least 18 cars up my 2.7% ‘hill’. The only way you are going to be able gauge the pulling power of your engines is by having standard weight/rolling charteristics of all of your rolling stock.
I use the actual pulling power of my engiens in grams that it can pull up all of the grades on my layout. I load the engine with some cars of a known weight (NMRA standards). I then add cars until the car just makes it up the hill. This is the tonnage rating for that engine. I repeat this all grades and put it on the tonnage rating chart.
Randy that is a 38" that drop down to 36" at the top turn. The fail was wheel spin. The BLI is all upgraded including the chip. That was NOT the grade they failed on it was the 1.6% coming from the other direction. That is a 47 ft run that is a constant climb at about 1.6% or less. Do the math 46ft with a rise of 14.375".
I will do all the cars but this was a move the cars from point A to point B type thing.
I like the “Tonnage” test. We will try that Tuesday with all the big stuff and just see. I have 30 weighted, heavyweight passgenger cars with the Kaddee wheels and trucks that roll if you breath on them. We can use that as a kknow load. ALSO I need to find my fish scale for the old boat. The one that did not weigh a minnow at 2 lbs!!
Thanks all for your time to answer this stupid post but with what it costs us for these engines I do get a little ticked sometimes.
I put one of my toys on a dyno and it pulled 100 hp LESS than the claim for the modifications that where made. We reset the fuel mix and timing and got our 100HP back plus 5 extra. Now all I ahve to do is find someplace to use the 785 HP it has.! I bet it would pull those 15 cars [:D]
A postal scale is better than a fish scale, either one off the fish or one to weigh him with. Digital trigger scale with a 1 oz. minimum may be ideal, but not cheap.
Cars that weigh less than the NMRA recommendation will allow you to pull more, IF they function well in all modes of use. Only you can make that decision. Two cars that are for all intents are ‘identical’ may not weigh the same to get excellent performance, and/or they may not roll the same. Therefore ‘tonnage’ may not be the best indicator.
My Y3s (well, the four I have tweaked, anyway-no traction tires on any darn it) will pull 30+ hopper trains up a 2% grade, no problem. My P2K Berk will do 24. My Athearn Mikes will do 21, 17, 16, and 16 respectively. Everything else will do more, freight wise. My Athearn Pacific will do at least 3 passenger cars - I don’t know what it will do maxed out because that all it ever has to pull. Everything else will do more - BLI Class A 75 plus something - ran out of room. The plating wearing off the tires a little on most any engine will help a lot, IMHO. Personally I love traction tires, but I am in the distinct minority. I do not see what prototypical has to do with it when talking about a steam loco powered by an electric motor, but again, that’s just me. When in doubt, add weight.
Unless you have 50 locos or more, the best test may be to find the worst and best pullers and then rank the rest relative to them. Doubleheading is fine and fun, but two mallets on a 30 hopper train ain’t prototypical either. When you get a new loco back it up to the best and see which will pull which for starters.
Thank you about the layout, small corner of it. The grooup is coming over tonight si I am going to have them test all 46 engines and see what they get. I have a digital readout and print scale that works down to .06 grams and up to 4,800 so no prblem with that. I have a hooper car and lead weight. Will make a SLED for these to pull up the grades. I expect the Big Boy to pull tree stupms since it is just the old design, weighs a ton and with twin motors should have it pretty easy with the loads. This should keep them busy all night long.
I agree. Traction tires are great, the difference in pulling power is just exponential. I put in quite a steep grade (7-8%) on my logging line, and had various geared locos from various makers that would barely make it. Some couldn’t haul themselves up, some could barely manage a car or two with lots of wheel slip and throttle ‘dancing’…None with traction tires. My Mantua with traction tires didn’t even flinch at charging right up with as many cars as I could pack on (though I only have 8 logging cars).
I’ve heard more objection that they get out of round than as non-prototypical myself. I’ve not had the out-of-round problem, but then again that complaint seems mostly associated with old Rivarossi locos and (perhaps) too soft a rubber in the tire. I have only one old Rivarossi like that and it’s not had any traction tire problems.
Aside: Despite initially thinking the “challenge” of that grade would be a fun ops area, I’ve subsequently decided I overdid it. Luckily the way it’s built makes it easy to back off the grade and that’s my major project for this coming weekend. I’ll probably cut it down to a “mere” 4% or so. My ‘incline board’ testing indicates that will let all of them ‘make the grade’ with a few cars at least.
Digital trigger scale with a 1 oz. minimum may be ideal, but not cheap.