Replacement 12V Motors

[roamingstop]

Im wondering if some tech-heads could help with the repair / replacement of a 12V motor from a red train motor?

When I received the motor the previous owner indicated that there was a 'clicking sound' from inside. Careful dis-assembly (following the 12V Motor thread) allowed me to get a first glimpse inside; and showed that there was clearly a problem with the commutator (?)

Lego 12V Red Motor Repair by roamingstudio, on Flickr

Careful removal of the motor showed that the commutator (?) had slipped off the motor; allowing the three metal pickup plates to become loose on the axis. The pickup plates are still connected to the transformer wires, but the soldering has fractured. There does not appear to be any burning through of the motor - just a mechanical failure.

Lego 12V Red Motor Repair by roamingstudio, on Flickr

Lego 12V Red Motor Repair by roamingstudio, on Flickr

This is what a normal motor should look like...

Lego 12V Motor Normal by roamingstudio, on Flickr

The question is whether anyone thinks this is really repairable (I have a decent SMD soldering iron etc; and could try to fix it with time and patience) or should I try to find another 12V motor which could replace it (does anyone know of a suitable replacement; other than another defect 12V motor).

If I have to give up on the motor - would it make sense to try and fit a modern PF motor inside the red chassis?

Thanks for any thoughts and tips.

Edit: Please note the original FlickR photos have annotations to show what I mean.

Edited January 27, 2013 by roamingstudio

[Shazam12]

Good morning,

Yes this is a common failure of the 12V motor. The motor has run hot and as a result the commutator started melting. Underneath the 3 copper plates that form the commutator is plastic so that has been deformed. Also, you will notice that the carbon brushes have been sheared off. I would also check the nylon gears on the axles to see if these have been damaged, which happens often.

To repair this, it will require a new commutator and brushes. I've been told they can be found at certain train hobby shops, but I've not been able to track them down.

I don't know why these motors run so hot that the plastic melts, anyone got ideas on that?

Edited January 27, 2013 by Shazam12

[roamingstop]

Thanks for the tips. We have an RC model shop in town which is very well known so i will see what they have. The threads (wheels n motor axle) all look to be in great condition and move smoothly. Just motor windings and commutators.

As to how they overheat - i guess pulling too much load / blocked wheels and high voltages allowing the current to runaway and heat the motors n plastic. A solution will be found!

[Shazam12]

Great, keep me posted if you find a solution and parts.

[bricks n bolts]

If I have to give up on the motor - would it make sense to try and fit a modern PF motor inside the red chassis?

Thanks for any thoughts and tips.

I don't know if that would fit, but if it can, the "Mottraxx" 263 motor you can get from Conrad is the 12v equivalent. Have swapped one of these out into a PF motor, the same motor also used in Railbricks article to replace the older '70s 12v motors.

[locoworks]

Good morning,

Yes this is a common failure of the 12V motor. The motor has run hot and as a result the commutator started melting. Underneath the 3 copper plates that form the commutator is plastic so that has been deformed. Also, you will notice that the carbon brushes have been sheared off. I would also check the nylon gears on the axles to see if these have been damaged, which happens often.

To repair this, it will require a new commutator and brushes. I've been told they can be found at certain train hobby shops, but I've not been able to track them down.

I don't know why these motors run so hot that the plastic melts, anyone got ideas on that?

it will be getting quite hot because the design looks to require a lot of current ?? the actual gear ratio between the motor spindle and the axles looks quite tall, the worms on the motor shaft have quite a coarse pitch, looking at the worm it appears to be a triple start thread? add to this the worm wheel ( gear on the axle ) is very small in diameter, so the actual gear ratio is likely to in 2 -1 or 3 -1 reduction ratio, very tall for that type of gear train. i think finding a double ended motor wound to give high torque and low revs will be a tough challenge. replacing the motor with a generic double ended can or open frame motor may be possible, but it won't help the gearing issue. as most motors used in 'normal' model railway loco's use gear ratios around the 30 -1 area you still end up with a loco that will travel twice the speed of a lego one so the motor is doing a lot of spinning and probably won't be suitable for the lego power unit. it may be possible to do a complete internal redesign with a gear reduction in there somewhere to allow a different motor to be used, but that is way beyond my abillity.

[Andromeda]

@ Roamingstudio

That's an F'er!

I looked at mine and the ceramic piece that has 'migrated' on yours, is only a solder point for the commutator.

Your main issue is that the commutators' contact/s have now become un-glued from the spindle/insulator.

I have successfully used brass tube to 'upgrade' 12v switch point motors, maybe you could use something similar to repair your motors' pickup?

A larger Dia. would be needed of course...

[Andromeda]

After I bit of poking around online I found the following article, which showed exactly what I failed to explain above. The Guy fixes a 30+year old motor!

http://www.instructa...mmutator/#step1

If it was an older 12v, with studs and no bogie, I would source from these guys as they are the orignal company commissioned by ogeL - Bühler:

http://www.buehlermo...EN/DC_EC_Motors

Edited February 1, 2013 by Andromeda

[alainneke]

Nice finds Andromeda! Actually, the motor in the 'newer' 12V bogie is also made by Buehler (and so is the transformer).

I think your best bet is to contact Buehler and ask them if they still make similar motors (a quick look at the current DC motor range shows that they don't have flat 12V motors with an axle all the way through, but who knows...). If they don't, have fun fixing the commutator :) Fitting a PF motor in there will be very hard, because the axle of the PF motor is way too short.

[Shazam12]

Buhler does not have anything for the 12V motors anymore, that is a thing of the past. Have been told that brushes and commutators can be sourced from elsewhere but have no leads on that.

[Andromeda]

Nice finds Andromeda! Actually, the motor in the 'newer' 12V bogie is also made by Buehler (and so is the transformer).

Indeed! I tried contacting them three or four days ago. I imagine it was all made under licence/contract...

So any unused parts were probably destroyed or returned to ogeL.

Buhler does not have anything for the 12V motors anymore, that is a thing of the past.

Fair enough, but I’m not convinced. The flat motors could be modded for the older 12V 14 studs long.

If these:

have three coils on the armature then Roamingstudio could ‘steal’ the commutator, esp. if they weren’t expensive, but you would need a ‘puller’ to remove it.

The spindles are of a comparative size, 2.01 on my 12V(my calliper is only two DP). So it is a question of tools, expense, 3 coil armature and W/r.p.m.

Even so if you are thinking of removing the commutator from the new motor, and it has a 4 coil armature, you might as well remove the armature as well…

My opened original motor pulls 140mA no load, and varying 200mA plus under load.

[hoeij]

Looks like you have a lot of damage to that motor.

I had two bad motors, but I managed to combine them into 1 good motor (plus some spare parts, that could be put together to make

a working motor, though not a very good one). With your motor, I'd probably not use it until I had some spare parts from another bad motor.

I don't know why these motors run so hot that the plastic melts, anyone got ideas on that?

It is possible to pull a huge train with just 1 motor, do this for a significant amount of time, and then overheat the motor that way.

But I think there is another explanation that is much more likely.

Many of these motors work great, but some of them need lubrication (I wonder if that has to do with the way the motor was stored for all these years?). The motors with lots of friction desperately need lubrication; otherwise, if you run them then they have to work

hard to overcome this friction, and that's how they overheat.

I've had motors that would not move until there was more than 6 volt on the track; after lubrication, they're already moving with less than 2 volts. This makes them run much less hot (which in turn means that I can safely pull a longer train).

[roamingstop]

Thanks for all the helpful answers; unfortunately chest infection stopped me getting out this week - but I hope to complete the project in the coming weeks based upon your comments.

[alainneke]

Sorry to bump this old thread, but I've recently come across a motor with a similar problem. Instead of trying to repair the commutator, I've decided to try and fit a readily available motor. It's still a WIP and also doesn't work yet, but I thought I'd share it with you.

LEGO 12V train motor repair (1) by alainneke, on Flickr

The axle of the motor (Motraxx 265) is 56mm, or 4mm shorter than the original one. If this causes problems, I'll probably fix it with some plastic bushes on each end of the axle

LEGO 12V train motor repair (3) by alainneke, on Flickr

Here you can see the axle mounted using the original LEGO magnets and housing

LEGO 12V train motor repair (4) by alainneke, on Flickr

So far so good, but I still have to figure out:

- how to remove the worm wheels from the old axle?

- the correct position for the carbon brushes: the motor will not run with the brushes in their original position, but it does run when I push some wires against the commutator

[roamingstop]

Thanks for posting - I had essentially given up hope. I wonder if alternative worm screws might be better than trying to remove 20 year old plastic. I'm guessing they are a friction push on (no sign of glue). But might need a special hammer and washer to ensure they slide off?

[alainneke]

Thanks for posting - I had essentially given up hope. I wonder if alternative worm screws might be better than trying to remove 20 year old plastic. I'm guessing they are a friction push on (no sign of glue). But might need a special hammer and washer to ensure they slide off?

I managed to get it running, by 'reversing' the carbon brushes. The other side of the brushes is smaller, so I suspect that it has something to do with their size. I'll try to fit the brushes that came with the new motor, and see what happens. It does run smooth btw, because of the five poles!

As for the worms: they appear to be made out of brass. Heating them didn't change the grip on the axle, and hammering/pulling them only results in damage, so I guess I'll have to make some new ones.

[Andromeda]

I managed to get it running, by 'reversing' the carbon brushes. The other side of the brushes is smaller, so I suspect that it has something to do with their size. I'll try to fit the brushes that came with the new motor, and see what happens. It does run smooth btw, because of the five poles!

Nice work Alainneke, this tek should inspire many others!

As for the worms: they appear to be made out of brass. Heating them didn't change the grip on the axle, and hammering/pulling them only results in damage, so I guess I'll have to make some new ones.

Did you use a threaded claw type puller? Maybe they used some anaerobic adhesive, I use it to lock screws in laptop repairs?

[alainneke]

Nice work Alainneke, this tek should inspire many others!

Did you use a threaded claw type puller? Maybe they used some anaerobic adhesive, I use it to lock screws in laptop repairs?

Thanks. I managed to get them of with a gear puller, which I bought some time ago. Alternatively, you could use a hammer and a 1,95mm drift pin to drive them of.

I'm still working on the axle btw, which is a little too short and moves back and forth when applying power to the motor.

[roamingstop]

Hmm having never heard of a gear puller - this link shows how to build one.

http://www.instructables.com/id/Cheap-and-Simple-Gear-Puller/

The spring summer have passed too rapidly and now that the autumn draws near perhaps I will find the time to complete the repairs of my 12V red motor.

Many thanks Alain

[Andromeda]

This was what my mind was picturing when I wrote this:

http://www.amazon.co...g/dp/B006B3PRL2

Having seen the home-made version, it looks more precise! The 'jaws' of the one above are prone to initially moving.

I imagine Alain would prefer your suggestion !

As the days grow short and the nights grow long, the Lego comes out to play !

[Afolbrickfox]

 

hello everyone! 

I also have the problem of the fused switch, I wanted to know if someone managed to fix it with the guide described above.

Gr. Alex

Edited January 19, 2021 by Afolbrickfox
traslate