Question Regarding Motor Number/Date Codes?

[Celeste]

Hi all!

Apologies if this has been asked before, but I couldn't find any information about it online. I have started running my trains for longer periods of time and noticed that one shakes a bit when running. I was told by a fellow LUG member that for dual motor trains, it's a good idea to get motors that were produced in the factory around the same time as there can be slight performance differences in batches over time. I was told that motors that aren't matched well will fight each other and cause shaking and quicker battery drain. It seems like the way to tell the production run is by the numerical code on the bottom (At least it seems that way for PU. I can't speak on the topic of PF or 9V). 

Does anyone know how to decode these numbers? Are they coded like car tires with a week and year? Is it something else? Are they uncracked as of yet? What does that mysterious "I" mean in the third digit slot?

It seems that identical numbers means the same production group as these four were ones I got directly from the Lego Store and were pulled from the same storage box.

For non-identical numbers, is there a rule as to which numbers should be closer? Is it more important that the first digit is the same or the last? Does it matter? I also took pictures of some of my other spare motors with a variety of numerical codes as examples.

Any thoughts or knowledge would be greatly appreciated!

JopieK, if this is an already discussed topic that I missed, please move or delete. Thanks!

 

[Phil B]

Just guessing, but these codes look exactly like the <Week>-<factory>-<Year> codes that are on set seals (Nowadays sometimes <Weekday><Week>-<Factory>-<Year>.

So your motors in the first picture are from week 16 of (202)2, from factory "I" (capital i). Not sure which factory that is, as it doesn't match up with the list I have:

 

H = Nyíregyháza, Hungary
R = Ciénega de Flores, Mexico
S = Kladno, Czech Republic
Q = Purkersdorf, Austria
B = Shenzhen, China (Not Confirmed)
M = Billund, Denmark (Not Confirmed) 
O = Billund, Denmark (Not Confirmed) 

[Celeste]

That makes sense. So, in theory, 30I9 and 29I9 should be close in performance. 

Is it possible they are made in a different factory due to being electronic parts? (I have no idea what I'm talking about)

[Stereo]

I only have 1 PF motor, but it's got the same type of code in a different spot - 48J4 between the anti-studs at one end.  Probably made in 2014 for a 60051.

Edited January 22 by Stereo

[Selander]

My gut feeling is that it is a bit exaggerated to try to match dual motors based on week/year manufacturing info.

I have three locomotives equipped with Powered Up dual train motors, and I've never noticed any running issues.

For any person really requiring an optimised duo of motors, I think each motor performance should be measured electronically and then paired with a similar "twin", rather than trusting the manufacturing dates...

[dr_spock]

Even if manufactured at the same time, motors can have different performance based on hours used, how much of your cat's hair is stuck in the mechanism, etc.  Maybe create a performance map based on each motor's rpm vs duty cycle.  Then use the maps in a controller to look up the duty cycle of each motor for the desired rpm. 

[SD100]

Your LUG member thinks they know a lot more than they actually do, and is making up a ridiculous over-complication. LEGO uses off the shelf actual motors and there is no guarantee that the motor inside the shell came from the same batch even if it was *assembled* directly after another one.

SD

[XG BC]

yup, and even between two motors the variation can be huge, even if they rolled off the assembly line right after the other one. the only way to 100% match rpm is closed loop control, with feedback. the motors are all close enough anyways. especially since these are toy train motors we are talking about here, not some precision drive motor for industrial or scientific use.

Edited January 22 by XG BC

[Celeste]

Thanks for all the input, everyone! Even though it seems like getting matching motors doesn’t really matter, I did enjoy finally finding out what those codes meant!

I’ll try and report back how my locos run with the new motors (whenever I have a layout again :) ). My guess is it will be a little smoother, but more to the motors being new/having the same amount of wear than the matching codes. Also the lack of cat hair will help :). 

[zephyr1934]

Do they shake more on curves? I think the mis-matched radii of the inside and outside rails might be enough that one or both wheels on a given axle will wind up bouncing a bit as it slips. Real trains self-level with the conical wheel surface naturally shifting slightly to match the radii, but the nearly flat and traction band equipped lego train motor wheels can't do that.

[XG BC]

i dont think lego makes a Differential small enough, otherwise we could test what impact that has on Performance and shaking (i have never noticed shaking either, but i only use one motor), or just have a Differential between the two bogies that get driven from a single axle and motor maybe?

[zephyr1934]

I wasn't talking about a differential. What I meant is that if you have a standard train motor block, each axle comes out and has a wheel on either side. On a curve the outside wheel has to travel further than the inside wheel. But they are on the same axle so they can't rotate at different speeds. So one or both of the wheels have to slip. I'm just hypothesizing that a wheel with a traction band repeatedly slipping on the rail all the way around a curve might cause the motor (and thus the entire locomotive) to bounce and wobble. As such, the wobble would be an unavoidable outcome of the motor design and one should expect to see it on PUp, PF, RC and 9v motors (but not 12v/4.5v when running on their native curves because they have a traction rail and a smooth rail). I've noticed that many of my engines wobbled when running but did not think much about it until reading this thread.

[Celeste]

After some non-scientific tests, I have some anecdotal results!

As a note, in between using the old motors and testing the new ones, I updated the Pybricks software I was using to control my double header locos. Basically, I'm just using one controller instead of two now, but it shouldn't impact the results.

Also noting that I did these tests on a carpet layout because that's what I had to work with, unfortunately. Next time I'm at a show, I'll try on a proper table layout.

However, I was surprised with the results. The locos were able to pull pretty much all the freight rolling stock I had on hand. About 30 small, 2 axle cars (Mostly light weight). The magnets became the weak point, though, so I had to shorten the train a little bit so it wouldn't snap in half through tight switches! After running it for half an hour or so at varying speeds with varying loads  (And fresh rechargeables), I found the performance was actually better. It was really hard to tell if the shaking was even there anymore, so it's either barely shaking or gone completely. It was clear they could go fast, and could *haul* ! I think it is due to the motors all starting out at the same point in terms of wear, but I think this is a good example of how pairing up motors of similar performance can impact the loco.

If anyone else has thoughts or experiences, I'd love to hear them!

Edited January 28 by Celeste

[dr_spock]

1x2 plates or tiles could be used to keep the magnetic couplers from uncoupling. 

[Celeste]

On 1/27/2025 at 9:37 PM, dr_spock said:

1x2 plates or tiles could be used to keep the magnetic couplers from uncoupling. 

I'm so mad at myself for constantly forgetting about that trick. 

I tried the other day and was able to get 26 cars being pulled. I forgot I also had a video of those same two locos pulling around the same number (though lighter) cars on an actual table layout before I switched the motors over. I don't see any shaking in it, but I do remember it happening at some point during that weekend of display. Might've been with heavier cars or low batteries. Who knows. It seems like if it does make a difference, it's not by much. Even if it's not hard data being pulled from these videos, it's still cool to see them run with long trains.

Here are the locos running before the motor switch.

And after on my carpeted living room.