ScaleTrains SD40-2 Pulling Tests

[C855B]

 A couple of weeks ago there was discussion about the ST SD40-2 being a little on the light side, which some felt had an impact on pulling ability. In that discussion I mentioned filling the speaker space on a non-sound unit with tungsten powder. I don't have the kind of scale sensitive enough to know how much weight was added, but tests this evening on a section of my layout with a 1% grade into a 2% grade on a curve indicated an improvement. Decoders are ESU LokPilot 5.

The stock SD40-2 (speaker cavity empty) had some wheel slip with 11 cars on the 2%, 12 cars was a full stall. The weight-added version was comfortable (little or no wheel slip) with 13 cars, 14 would stall. There was, very roughly, a 15% improvement in traction.

Running them mu'ed up the same 2% hill (with six or so cars still on 1%) netted 30 cars with no slip. Photo below shows most of the test train with the power just past the apex. Adding the tungsten powder wasn't all that difficult, but potentially messy. I sealed the hole in the speaker box for the wires with small scrap of styrene sheet, poured the powder with a spoon, and eventually sealed the powder into the box with UV-activated CA. Electrical tape worked, but was too thick and lowered the fuel tank enough to lift the wheels off the rails (oops!).

Will I add the weight to the three others I have? Undecided since I will usually run them as a brace of four, more than enough for any train that will reasonably fit on the layout.

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[Ed Kapuscinski]

That photo reminds me.

GET BACK TO WORK ON THE LAYOUT CHACHI! lol.

[MK]

Chachi???!!!!  You're dating yourself Ed.   

[Ed Kapuscinski]

Chachi???!!!!  You're dating yourself Ed.   

I would if I could. lol

[C855B]

That photo reminds me.

GET BACK TO WORK ON THE LAYOUT CHACHI! lol.

Don't you know it. The way things are at home these days I'm lucky to get over there two hours a week. It's sad. 

[peteski]

I don't have the kind of scale sensitive enough to know how much weight was added . . .

No precision scale?!
 Here you go: https://www.ebay.com/itm/283381549026  500g capacity, 0.01g resolution, 7 bucks with free shipping)!!  Can't' afford not to have  one.  I bought it and it works.  Not only shows the weight in several units, it is also a counting scale

[Rivet Miscounter]

Thanks for this feedback.   Did you test two mu'd without weight added?  I'm curious what the result of that would be.  (those of us that bought sound-equipped would be stuck with that result if we wanted to keep the sound)

[C855B]

Thanks for this feedback.   Did you test two mu'd without weight added?  I'm curious what the result of that would be.  (those of us that bought sound-equipped would be stuck with that result if we wanted to keep the sound)

Not yet. The two I was running last night are the only ones with decoders at this point. Maybe tonight for one more, but no promises. Getting away from the house is genuinely a challenge.

Installing decoders on the DC version is an amazing PITA in trying to preserve those sand lines bracketing each truck. I already lost one to the wind. Like my semi-rant in the other thread, I appreciate the attention to detail, but I may sacrifice this particular feature on the entire fleet in the name of maintainability.

[Rivet Miscounter]

Not yet. The two I was running last night are the only ones with decoders at this point. Maybe tonight for one more, but no promises. Getting away from the house is genuinely a challenge.

No worries, no need to do that.   Just thought maybe you had done it and didn't think it worth reporting.   When/if you get to it, I appreciate it.

[C855B]

Errand running gave me an excuse to drop by the studio to decoder another. Getting the hang of it. Anyway...

Yeah, a bit of a difference with two stock (unweighted) units versus 1+1. The unweighted consist with 30 cars started to slip noticeably about 3/4 the way up the hill. With 32 it stalled about the same point. 1+1 made it all the way up with 32 and only a touch of slip.

Of course, all three on the point walked right up the hill with the entire 36-car test train. And it was beautiful, too.

[C855B]

No precision scale?!
 Here you go: https://www.ebay.com/itm/283381549026  500g capacity, 0.01g resolution, 7 bucks with free shipping)!!  Can't' afford not to have  one.  I bought it and it works.  Not only shows the weight in several units, it is also a counting scale

Took your advice and searched around for a slightly larger version. Cost a whopping $3 more. Didn't realize gram scales were this cheap.

I will say, after the session this afternoon testing the difference, just in the handling I noticed the weighted version had a little more "heft". The scale will be good for quantifying that heft.

[peteski]

Took your advice and searched around for a slightly larger version. Cost a whopping $3 more. Didn't realize gram scales were this cheap.

Those digital scales seem to be like handheld calculators. Originally bulky and expensive, but nowadays they are everywhere, often included free as promotions. Pretty much disposable. And the contemporary version have many more mathematical functions than the original basic four.

I suspect that this is due to mass production (read: very inexpensive) of the highly integrated chip which is the brain of the scale. Same goes for the strain gauges. Those are probably dime-a-dozen nowadays.  Ah, the modern technology . . .

[Rivet Miscounter]

Errand running gave me an excuse to drop by the studio to decoder another. Getting the hang of it. Anyway...

Yeah, a bit of a difference with two stock (unweighted) units versus 1+1. The unweighted consist with 30 cars started to slip noticeably about 3/4 the way up the hill. With 32 it stalled about the same point. 1+1 made it all the way up with 32 and only a touch of slip.

Of course, all three on the point walked right up the hill with the entire 36-car test train. And it was beautiful, too.

Thanks, all good info.   Maybe I can come down off the proverbial window ledge a little. 

My immediate plans for running N trains will be Free-moN, which is largely dead flat.  But eventually I may revisit a home layout concept that would most certainly employ a helix.  I plan to run three locos for my longest coal drags that I anticipate being either 32 cars (more likely) or 36 cars.   I was expecting to be maybe 2 "heavy" locos and 1 sound, or 2 sound and 1 "heavy", and then maybe 1 "heavy" as a helper.  From your testing it sounds like I should be fine.  Might even get by with the helper not being a heavy.

[Rivet Miscounter]

Took your advice and searched around for a slightly larger version. Cost a whopping $3 more.

Link?

[C855B]

https://www.ebay.com/itm/325421017885