Measuring "Pulling Power"

@Arthur P. Bloom posted:

The absolute power in kilowatts x 10^-n delivered to the drawbar seems to be an elusive answer, given the many variables: Voltage, track and wheel cleanliness, humidity, temperature, phase of the moon, mother's blood type, etc.

It’s not elusive at all.  If you truly want “power” in the engineering textbook sense, just measure the pulling force over some distance and time.  That’s all a horsepower is.  I think it’s defined by lifting 33,600 lbs 1 foot in 1 minute or something.

Maybe i am just a simple old guy but if a locomotive can pull a train around my layout and up the single grade the it has sufficient pulling power, no further technology required.

The real problem here is that we are not measuring POWER, we are measuring TRACTIVE EFFORT, which is a static force, not a measurement of power.

Consequently, the fish scale, spring scale, digital scale, etc. are all you need to measure it.

Boggles my mind that this simple topic has run to two pages!

Right...

@Norm Charbonneau posted:

You guys are mixing up force and power engineering units of measure. It’s a little upsetting to me as a professional calibrator.

You will also need to measure distance and time to complete the power calculation.  P=(FD)/T

Be sure to take a few runs at the measurement, discard the data, reset the load measuring device to zero force, then record last run. This will remove hysteresis from the load train and the sensor/scale.

Seriously, thank you for the knowledge-based feedback with a formula-- great!

And, if you're the same Norm that is able to take a drive bisecting Detroit's 'burbs in order to walk-into P&D Hobby rather than pay shipping charges-- I'm feeling, "Wish I could do that!" This is especially true due to having been raised in Detroit and having been able to combine a trip to P&D with my commute to Metro Beach where I Life Guarded "100 years ago."

I don’t run more than 15 or 20 cars so pulling power has never been an issue for me. If you run Legacy or DCS and don’t want to shorten the train then simply add an engine or two or three or four, etc.

Or use a bigger engine.

@Mannyrock posted:

Guys,

I have read alot of posts on this board over the past year, and many of them discuss problems with, or no problems with, the pulling power of locomotives.

Is there a standard way measure the actual "pulling power" of a locomotive?  Seems like there should be.

A simple spring loaded gauge, measuring "pull" in fractions of ounces,  would seem to be in order.   Hook the gauge to the back of your locomotive, hold the gauge in one place, turn the locomotive on full power, and see how far it moves the gauge until it spins or stalls.

(A simple device like this is available for measuring the weight of "trigger pull" for firearms, but it is generally gauged in quarter of a pound marks, from 1 pound up to 8 or 9 pounds.  It tell how much weight must be applied to a trigger before the gun fires, i.e. lets the firing pin go.)

Mannyrock

At what point will the coupler fail?

We did a "Pulling Power" episode on The Train Shop Weekly that had some interesting results.

The Train Shop Weekly Vol.1 - No. 18 "Pulling Power"

I should have been there with my Big Boy, that would have kicked all your butts!

@gunrunnerjohn posted:

I should have been there with my Big Boy, that would have kicked all your butts!

We need to get you on the show with it. The PE Berk put up a pretty big number. 😂

John - nice video - looks like your layout is up and running.  Nice display of power - of course, those are all empties, right ...  Now about that smoking tanker in the middle of your consist - aren't you worried that some 1:48 scale FRA inspector is gonna come banging on your door worried about the emissions and/or whether its gonna blow??

@Bill Henning posted:

We need to get you on the show with it. The PE Berk put up a pretty big number. 😂

If you remember the previous testing with Richard's track pulling power rig, my VL-BB chalked up right at 7 pounds of pulling power and was the pulling champ for any single engine.  I think I can whip the 40oz pull of the PE Berk!

@richs09 posted:

John - nice video - looks like your layout is up and running.  Nice display of power - of course, those are all empties, right ...

Empties?  Not a chance, this was a revenue freight!

@richs09 posted:

Now about that smoking tanker in the middle of your consist - aren't you worried that some 1:48 scale FRA inspector is gonna come banging on your door worried about the emissions and/or whether its gonna blow??

That's a LOX car, it has to have venting or it would blow.   The "venting" is pure oxygen, at least in the real world.

Now, if I had turned on the smoke on the MegaSteam car, that would be different...

John you got me by 14 cars but I was using two Diesels. Your train looked fantastic. I am a sucker for long trains. Have you ever tried DPU in the middle that is powered? I did once and it was great till the middle unit lost poser on a bridge and the train straight lined! Interesting topic this pulling power!

Two diesels?  Gosh, for two diesels, I pull 115 cars!   Yep, DPU in the middle, that reduced the strain on the couplers.

I found the most significant method of getting improved pulling power from all my engines, and more consequential than adding a 2nd engine, was to remove years and years of Goo-Gone residue that--unbeknownst to me--had built up on the track.