Unusual Lima motor polarity problem

[GWR-fan]

I have numerous mint Lima diesel/electric locomotives that remain in storage.  As a move to dilute the fleet I decided to test some of them for sale.  Normally I would only test one loco at a time and not take note of the controller set direction and the actual loco direction.  One loco surprisingly operated reverse polarity to the rest so I decided to reverse the connections on the motor.  The actual track to motor terminal connections were standard Lima format with the motor bogie pickup to the left brush terminal on the motor and the unpowered bogie pickup to the right brush terminal.  Reversing the pickup wires corrected the direction issue although I have never seen a loco wired like this previously and I have seen many, many Lima locomotives.

 

After a little running I noticed the speed in one direction was slow and erratic and so decided to clean the armature.  I reassembled,  however the loco was not particularly fast like previously and the armature was getting warm.  I decided to replace the armature with a spare salvaged from a CD motor drive conversion.  I refitted the replacement armature expecting that I would need to return the pickup wires to a normal configuration,  however, even with the wires reversed the loco direction ran normal to the selected controller set position.  I am wondering if by sheer chance I had selected a spare armature that possibly had been wound incorrectly at the factory like I presume the faulty original armature had been.  I have never noticed this polarity issue previously and am wondering if perhaps Lima's quality control was lacking when it came to armature winding.  

[SRman]

Rather than the motor windings being at fault, I would suspect the actual ringfield magnet as having the reversed polarity, or being installed upside down, if that is possible (it may be that it isn't possible to mount it the other way up if there are any tabs or slots or cutouts that help locate it).

[kevinlms]

Magnet reversed after someone has dismantled it?

 

I don't believe I've ever taken the magnet out, or indeed is it possible?

 

Beaten by SRman!

Edited May 18, 2020 by kevinlms

[GWR-fan]

Many thanks,  I had not considered the magnet pole position.   The loco is as new and I doubt had ever been dismantled previously.  From memory on other motors I have rebuilt there is a little tab at the 12 o'clock position on the magnet ring that fits in a slot in the motor casing.  

Edited May 18, 2020 by GWR-fan
Additional info

[giz]

I remember having one that ran in reverse from new. I reversed the magnet and while doing it noticed that the tab hadn't been properly located before so I assumed factory assembly error.

[GWR-fan]

Thankyou.

[GWR-fan]

Ironic.  The very next Lima loco I disassembled had the motor terminals interchanged as obviously a previous owner had attempted a repair and inserted the magnet in the wrong location.  Also,  the brush spring had been cut in half and extended as he most likely lost a spring during the attempted repair and used one spring to repair the motor.

Edited May 20, 2020 by GWR-fan
Spelling

[john new]

On 18/05/2020 at 08:09, GWR-fan said:

I have numerous mint Lima diesel/electric locomotives that remain in storage.  As a move to dilute the fleet I decided to test some of them for sale.  Normally I would only test one loco at a time and not take note of the controller set direction and the actual loco direction.  One loco surprisingly operated reverse polarity to the rest so I decided to reverse the connections on the motor.  The actual track to motor terminal connections were standard Lima format with the motor bogie pickup to the left brush terminal on the motor and the unpowered bogie pickup to the right brush terminal.  Reversing the pickup wires corrected the direction issue although I have never seen a loco wired like this previously and I have seen many, many Lima locomotives.

 

After a little running I noticed the speed in one direction was slow and erratic and so decided to clean the armature.  I reassembled,  however the loco was not particularly fast like previously and the armature was getting warm.  I decided to replace the armature with a spare salvaged from a CD motor drive conversion.  I refitted the replacement armature expecting that I would need to return the pickup wires to a normal configuration,  however, even with the wires reversed the loco direction ran normal to the selected controller set position.  I am wondering if by sheer chance I had selected a spare armature that possibly had been wound incorrectly at the factory like I presume the faulty original armature had been.  I have never noticed this polarity issue previously and am wondering if perhaps Lima's quality control was lacking when it came to armature winding.  

Apologies for reactivating an old thread. The club layout we were running at the open day last weekend is GWR/SR so I dug a few locos out of storage that, because I have been running LNER/ER at home, possibly haven't been out for over 10 years. 

 

I have discovered I have a similar runs wrong way round issue on a Lima 45xx Prairie. Doing the obvious, swapping the motor leads over, doesn't seem to have made any difference. I am pretty sure it has been stripped and rewired in the past as both motor leads are black! (Not good practice). Although it runs wrong road about it is otherwise not a bad runner for its age so is worth fettling for future use on Axford (the club layout).

 

1) Should I assume the magnet is the problem as per earlier replies to this OP?

2) If I take it out to reverse it are there any safety strips or anything that need to be added across the poles first? (I assume there is a gap) to avoid losing magnetism. Reason for asking is I recall needing to do that if you take the magnet out of old H Dublo locos.

 

As per standard advice I want to have it running properly on DC before I think about hard wiring a decoder into it and add any extra complications.

 

Thanks in advance for any responses.

[stewartingram]

Don't take it out to reverse it and risk demagnetisation (likely).

There are 2 ways to correct a loco running wrong way.

1] change the polarity of the magnet (I'd do that with my remagnetiser).

2] reverse the wiring to the motor brushes. If you have already swapped them and there is no difference, sorry, but double check that! Swap them again - label the 1st wire you remove just to make sure you are doing it right.

If you swop the wires to the brushes it MUST change the direction.

[john new]

10 hours ago, stewartingram said:

Don't take it out to reverse it and risk demagnetisation (likely).

There are 2 ways to correct a loco running wrong way.

1] change the polarity of the magnet (I'd do that with my remagnetiser).

2] reverse the wiring to the motor brushes. If you have already swapped them and there is no difference, sorry, but double check that! Swap them again - label the 1st wire you remove just to make sure you are doing it right.

If you swop the wires to the brushes it MUST change the direction.

Done. Somehow I must have reattached them the same way round the first time.

 

Thanks for the confirmation @stewartingram that it had to be a simple crossed wire issue not the magnet. The wires, as inherited, were somewhat tangled so I might have missed one cross over in the leads when I disentangled them the first time. 

 

Edited May 2 by john new
added the omitted pair of words!

[kevinlms]

3 hours ago, stewartingram said:

Don't take it out to reverse it and risk demagnetisation (likely).

There are 2 ways to correct a loco running wrong way.

1] change the polarity of the magnet (I'd do that with my remagnetiser).

2] reverse the wiring to the motor brushes. If you have already swapped them and there is no difference, sorry, but double check that! Swap them again - label the 1st wire you remove just to make sure you are doing it right.

If you swop the wires to the brushes it MUST change the direction.

The last point is true if using DCC too!

[andyman7]

3 hours ago, stewartingram said:

Don't take it out to reverse it and risk demagnetisation (likely).

There are 2 ways to correct a loco running wrong way.

1] change the polarity of the magnet (I'd do that with my remagnetiser).

2] reverse the wiring to the motor brushes. If you have already swapped them and there is no difference, sorry, but double check that! Swap them again - label the 1st wire you remove just to make sure you are doing it right.

If you swop the wires to the brushes it MUST change the direction.

 

28 minutes ago, kevinlms said:

The last point is true if using DCC too!

Which presumably makes it the Luddite solution to altering CV29 🙂

[Robin C]

I think Lima were built in Italy. You most probably got the European version & not the UK one. Think in Italy they drive on the opposite side to us? Hope this helps.

[Halvarras]

On 02/05/2024 at 11:24, stewartingram said:

Don't take it out to reverse it and risk demagnetisation (likely).

 

This may be so if the magnetic strip is removed from its steel holder, but otherwise it should be OK. If a previous owner has removed the magnet and re-inserted it the other way round the demagnetisation problem probably already exists! 

I rebuilt a motor bogie last year which required complete disassembly (magnet + holder excluded!) and it's working fine. As others have said if the magnet + holder have been inserted the wrong way round - which should be obvious as on taking off the face plate you'll see shiny steel instead of brown magnetic strip - the central locating pip at the top won't engage properly with its hole in the plastic outer casing.

 

1 hour ago, Robin C said:

I think Lima were built in Italy. You most probably got the European version & not the UK one. Think in Italy they drive on the opposite side to us? Hope this helps.

 

Um...........not really 😁!!

[Il Grifone]

On 03/05/2024 at 12:26, Robin C said:

I think Lima were built in Italy. You most probably got the European version & not the UK one. Think in Italy they drive on the opposite side to us? Hope this helps.

 

Except that Italian trains run on the left. They only drive on the wrong side* on the roads.

 

All my Lima run the same way as everything else. The convention is right hand rail positive for forward motion.

 

* Something to do with Napoleon I understand.

[DCB]

So why do some trains have left hand drive engines driving on the left.  I asked an ex WR fireman and he shrugged his shoulders   Apparently as far as I can tell GWR drivers used to keep their swords in a scabbard on their left as they were right handed which made it easy to draw their sword when the espied an adversary.
Manty other companies  drivers drove on the left to keep well away from sword wielding GWR drivers approaching from the other direction.    Like wise many pre WW2 French Bugatti cars were Right Hand drive yet they  drove on the right. 

[kevinlms]

Wasn't just the GWR, the Midland Railway was another large railway that had the driver on the right. The LMS built many Midland designed locos to the Midland standard of RHD, before changing to LHD part of the way through construction runs.

The GNR also drove from the right, although some A1's were converted to LHD in LNER days. No LMS locos were ever converted.

[john new]

1 hour ago, DCB said:

So why do some trains have left hand drive engines driving on the left.  I asked an ex WR fireman and he shrugged his shoulders   Apparently as far as I can tell GWR drivers used to keep their swords in a scabbard on their left as they were right handed which made it easy to draw their sword when the espied an adversary.
Manty other companies  drivers drove on the left to keep well away from sword wielding GWR drivers approaching from the other direction.    Like wise many pre WW2 French Bugatti cars were Right Hand drive yet they  drove on the right. 

One reason on the railways is probably the Company’s adopted signal positioning/sighting. I am no expert on it, though I have a recollection of being surprised that some lines also had their signals on the right even though the running line was to the left.

[Il Grifone]

The signals were sited on the left, so it seems logical to drive on the left. It's not like on the roads where you have to look out for the idiots coming the other way.