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Locomotive pulling power


rbrown7713
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It seems that I have read somewhere on this forum that someone has discussed the use of a test stand to determine the tractive force or pulling power of a locomotive, can't find it.  Has anyone built one?, and if they have, could you share the mechanics of the setup or discuss how one is built, before I go into the blind with making one. Bob.

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When I do my pull force tests I dont build anything.  I use a digital fish scale, hook it on the back of the engine/tender coupler, hold the other end of the scale down on the track firmly and start the pull test and read what the scale shows and make a note of the average I'm seeing.

 

Scale like this:  https://www.amazon.com/dp/B00W9ME9AE?tag=amz-mkt-opr-us-20&ascsubtag=1ba00-01000-org00-def00-other-nomod-us000-pcomp-feature-pcomp-wm-1-wl-ask1&ref=bit_pcomp_ask 

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Sure thing :)

 

The strongest locos I've tested are the USA Big Boy=8lbs pull force, MTH big Boy=7.5 to 8lbs pull force (MTH has traction tires, USA does not, that is why it pulls so strong vs the much heavier USA).

 

I recall Aristocraft Dash-9 was like 5lbs.  The Aristocraft loco pulling force depends a lot on if the wheel surfaces have worn down past the shiny coating.  if still coated it pulls less than when worn exposing the brass wheel itself.  I'd have to look up some of the other numbers.

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I tested the T1 weighing in at 11lbs.14 oz. and it pulled 2lbs. 7oz. and I don't know where I will put all of that weight. Also, this T1 only has one motor that came out of an F3.  Does anyone know what 2lbs. 7oz. traction force equates to the number of cars that it will pull?  I think I will test some of my other locos to compare. Bob.

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Hehehe...

 

You might be able to get a general idea but I dont know that you can get it that black and white and equate x number of lbs pull force to # of cars because you have too many other factors such as tightness of diameter of curves, steepness of grades, number of axles per car (the more axles per car the greater the drag), weight of each car, etc.  At the last trainshow Chuck and I did here in KC a number of years ago, we hooked up 120 Bachmann coal hoppers behind one MTH Big Boy and it pulled it around an oval with 20ft diameter curves (was on perfectly level ground).  As I recall there was some minor wheel slippage that while not obvious to the eye could be measured by the fact another Big Boy that was running alone would be a few inches further away from the pulling BB each time it completed a loop around.  The engine clearly could have pulled more but I dont know how many before slippage became unreasonable.  I would honestly just focus on getting your engine to pull the load you want/need it to.  Add the weight you think it should have then test run it.  If it's slipping too much, add some weight and retest.  Honestly I think people should go with just enough weight to pull the loads you need and not go a lot over it to limit necessary drive train wear.  

 

If you are really concerned about maximum pulling force and the engine isn't pulling what you need and you've already added the max amount of weight you feel comfortable with, consider lathing grooves in some drivers for some traction tires and you will for sure fix your problem. 

 

And actually that video above is really just a perfect demonstration on what traction tires do for you.  That MTH Big Boy with 8 traction tires can pull stumps it has so much traction.  8lbs of pull force is a LOT!

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Thanks Ray, you have given me something to go on. I just tested the P42, the only added weight are the three batteries, it has two motors with one truck with traction tires and it weighs 8lbs. 11 oz. and pulled the same as the T1, 2lbs. 7oz. The T1 has no traction tires.  On either of the locos. the T1 or the P42, all that I will be pulling would be up to 10 cars and I think that either of the locos. will pull that many, so I think that I am good, and thanks for your help, you have been very informative and I have learned something, thanks again.  Hey everyone, test some locos, state their weight, how man motors, traction tires or not, how many cars it will pull, or pulling force and we will all learn more. Bob.

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