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Offline Poor Skeleton  
#1 Posted : 22 June 2019 01:15:54(UTC)
Poor Skeleton

United Kingdom   
Joined: 09/10/2015(UTC)
Posts: 123
Location: England, Cambridge
I've observed before how my steam locomotives run much more smoothly than my diesels. I've always assumed this was something to do with the mechanics of the bogie transmission.

However, this week one of my 88786 Class 218s started running particularly poorly. After a lot of dismantling, cleaning, reassembly and testing I concluded that the problem actually lies with the motor itself. In checking out the behaviour of the motor, I noted that its smooth running was VERY sensitive to the position and tension of the brushes (even a small movement of the suppression capacitor could affect its running) and that even completely isolated from the rest of the gearing the motor changes speed spontaneously for no apparent reason.

This is behaviour I've observed with other bogie locomotives I have (all with the same E211 903 motor) and which I have put down to poor electrical pick-up and mechanical problems. I'm now pretty convinced it's the motor itself that's at fault.

I've ordered another motor and spare brushes, but I don't really expect either to fix the problem (as it's not just one loco that's suffering from this). My suspicion is that something about this motor (maybe the stresses caused by having gears on both ends) causes it not to run freely.

I've read other comments here how adjusting the brush tension profoundly affects the running of the motor so I'd be interested to hear if people have other observations and, perhaps, remedies. I'm not sure I can wait until the Class 218s and Ludmillas are re-issued with coreless motors!

Cheers


Chris
Offline husafreak  
#2 Posted : 22 June 2019 06:15:36(UTC)
husafreak

United States   
Joined: 09/04/2019(UTC)
Posts: 72
Location: California, Bay Area
Let us know how it goes. I have a Ludmilla "Tiger" from the 81451 set which is probably my most idiosyncratic loco. It requires very little power to go and speeds up at every point where track power is supplied. It is funny that way... It has the same motor as yours. I also had a lot of trouble getting it to run well and it was purchased new. I did change the brushes on it but I decided the actual problem was caused by a bent contact in the chassis not touching the the circuit board properly. I found one set of bogie wheels was not powering the motor. I wrote about my experience on the AZL forum as it was the first time I worked on a model loco. Anyway it is running well now. But check out this article from Exact Modellbau in Germany:

https://translate.google...NiOFP_e2JKbs5Pk-WjphYWSw

It is a wacky translation and probably not your exact problem but I thought you would get a kick out of it.
thanks 1 user liked this useful post by husafreak
Offline Poor Skeleton  
#3 Posted : 23 June 2019 21:54:18(UTC)
Poor Skeleton

United Kingdom   
Joined: 09/10/2015(UTC)
Posts: 123
Location: England, Cambridge
Thanks very much for that - very interesting! It's a shame, though, that there aren't before and after videos so we can judge how much of an improvement all that work made.

My Class 218 is running a bit better now, although I'm not sure of what I did to achieve this. I did slacken off some of the fixing screws and adjust the brushes a bit, so maybe the drive shafts were binding.

Cheers


Chris
Offline husafreak  
#4 Posted : 23 June 2019 23:03:33(UTC)
husafreak

United States   
Joined: 09/04/2019(UTC)
Posts: 72
Location: California, Bay Area
That sounds entirely possible. I recently went through a few maintenance sessions trying to get a V60 to run well, including replacement brushes, (another new loco but when I inspected the brushes one of them was broken, so a chisel shape instead of concave curve) I was baffled when that didn’t solve the problem! I finally realized that the motor body, the magnets, was a press on fit to the frame, a motor simply held together by friction! So pressing the housing firmly in place finally got it running well. I also read about a poor running modern loco on Z Trains Weekly blog on the Marklin 89923 where the problem was traced to a poorly aligned motor which uses pins to align it, in that case the pins were not engaged and the motor was screwed in but obviously not all the way into position, thus poor gear mesh. So unfortunately we are finding quality control or questionable design choices in some Marklin z scale locos, nothing we can’t fix though ;)

Edited by user 06 July 2019 05:23:36(UTC)  | Reason: Not specified

Offline parakiet  
#5 Posted : 30 June 2019 11:01:36(UTC)
parakiet

Belgium   
Joined: 20/02/2017(UTC)
Posts: 13
Location: Flanders!
I am totally flabergasted.

All my bogie ones run superb. Newly bought or ebay lottery.

while 50% of my big steamers have one problem or another
Offline GaryTrooper  
#6 Posted : 30 June 2019 20:56:58(UTC)
GaryTrooper

United States   
Joined: 26/01/2018(UTC)
Posts: 163
Location: Hailey, Idaho
I find each locomotive to have personalities of their own and each one requires some tweaking to some degree.
G - LGB
O - Lionel and MTH
HO - Marklin
N - Mix of manufacturers mostly Kato
Offline Poor Skeleton  
#7 Posted : 30 June 2019 23:38:13(UTC)
Poor Skeleton

United Kingdom   
Joined: 09/10/2015(UTC)
Posts: 123
Location: England, Cambridge
Originally Posted by: parakiet Go to Quoted Post
I am totally flabergasted.

All my bogie ones run superb. Newly bought or ebay lottery.


Now it's my turn to be surprised! None of my bogie locomotives with 5 pole motors run smoothly at low-ish speeds although, as GaryTrooper said, they are all different - even my two 88786s have completely different running characteristics! I don't have any large steam locos, but a couple of 0-10-0s and a couple of 2-6-2s are they run beautifully smoothly at all speeds.

What I've observed recently, is that the locomotives also behave very differently depending upon which direction they're running in - surprising given they're very symmetrical! Another thing I've noticed that they all suffer from to a greater or lesser extent is change in speed at the same throttle setting. At first I thought this was a pick-up problem, but I'm increasingly convinced it's related to the motor. In extreme cases a logo will be running nicely at moderate speed and will spontaneously slow down for no reason. Needless to say, I've checked that the mechanics are all running smoothly.

My current theory is that the brushes can move in operation affecting contact onto the commutator. There is a fair amount of slop and I can imagine if they were to change angle that would affect contact effectiveness and mechanical resistance. My new brushes arrived last week and I noticed they all have a blob of solder on the rear of the brush. I wonder if Marklin have realised there is a problem with contact and that's why they're now being soldered?

Finally, GaryTropper mentioned that all locos need a bit of fine tuning - I'd be interested to hear exactly what sort of fine tuning he finds effective. I've spent hours tweaking and checking and on several occasions thought I'd the cause of the problem, only for it to make n difference at all!

All the best


Chris
Offline parakiet  
#8 Posted : 05 July 2019 19:53:27(UTC)
parakiet

Belgium   
Joined: 20/02/2017(UTC)
Posts: 13
Location: Flanders!
Originally Posted by: Poor Skeleton Go to Quoted Post



Finally, GaryTropper mentioned that all locos need a bit of fine tuning - I'd be interested to hear exactly what sort of fine tuning he finds effective. I've spent hours tweaking and checking and on several occasions thought I'd the cause of the problem, only for it to make n difference at all!

All the best


Chris


I know nothing about repearing loco's. Read up and watched hours of youtubes.. still hard to jump in :)

3 years ago I bought a new 5pole version of a 3pole BR74 I already had. Nothing but problems.. So since then I try to score stuff of ebay etc.

Anyway, I have enough to tinker with one while the others drive :p
Offline Poor Skeleton  
#9 Posted : 06 July 2019 18:52:54(UTC)
Poor Skeleton

United Kingdom   
Joined: 09/10/2015(UTC)
Posts: 123
Location: England, Cambridge
By way of conclusion (of some sort) to this topic, I thought I should post my latest findings.

Having disassembled my two class 218s countless times, I concluded that the commutator on one of the motors was running eccentrically - you could see the brushes moving in and out as the motor turned. You could also see that one of the commutator slots was wider than the others. Anyway, after my examinations and attempt to smooth down the commutator, that motor is never going to run under its own steam again. Fortunately, I had a replacement and with that the loco is running reasonably again.

The second Class 218 was still not running well. I adjusted the brushes a bit so they say parallel to the motor housing and this helped a fair amount, but the real breakthrough was in replacing the brushes altogether. As well as the blob of solder I noted earlier, the profile of the new bushes is different to the old ones - they're quite a bit narrower and I suspect that is quite significant. That loco is running pretty smoothly now - it's probably the best of all my bogie locomotives and I'm now wondering if I should replace the brushes on all of them.

I do think that the coreless motor is the answer, though. My V200 runs very smoothly and the speed doesn't seem to waver at all.

It doesn't seem to be featured in the new product listings but hidden in the Maerklin website is a new Class 218 (88780) with coreless motor. I'll definitely be checking that out when it's available. I'm hoping that it might be possible to buy the parts to convert my old ones, as well, if the performance is as big an improvement as I expect it will be. Which will only leave the Ludmhilla awaiting the coreless upgrade...

Hope this is of interest.


Chris
Offline husafreak  
#10 Posted : 07 July 2019 03:54:23(UTC)
husafreak

United States   
Joined: 09/04/2019(UTC)
Posts: 72
Location: California, Bay Area
Thanks for posting, I have been following with interest and hoping for the best. I guess I got lucky as all of my Marklin loco's are running well now. But it took a lot of redo's on some, just disassembling and reassembling, playing with clearances, etc. I was doing things like swapping brushes left to right. I was also surprised to see "blobs" of solder on Marklin brushes. I have been working with electric motors as a hobby my entire life and I have never seen that. But that is indeed the way they are coming from the factory. And of the 3 sets of replacement brushes I bought two of them came with a broken brush in the package. The brush material "coal" breaks at the point where it is stressed passing through the spring steel. One of the brushes on a new loco had broken at the tip creating a chisel shape, another was protruding from the spring at an odd angle. In conclusion I had 4 unusable brushes out of 8. That includes the set in the loco. But those 4 good brushes have my 2 problem locos running well now. These are the long side mounted brushes. I also replaced the short top loading brushes on one of my other locos with ease, a simple swap to a better running loco. Note that these are all 5 pole Marklin motors and all steam type engines. All but one was purchased in "new" condition. So obviously there is a problem. It may be that as technology shifted to coreless and sealed motors the quality of the old type of brushed, rebuildable, motors has declined. Since I am new to trains I put my surprise aside and just got to work on them. I found it quite fascinating to work on them. My dealer was very supportive, replacing the faulty brushes as well. Some hobbies you just expect everything to work and others, well, not so much!
I asked myself in the very beginning if maybe I should avoid the older brushed motors, but I have some 5 pole locos that run fantastic now and I really like them so I guess I will always be in the market for a nice engine regardless of its power system.
Offline kiwiAlan  
#11 Posted : 07 July 2019 15:14:30(UTC)
kiwiAlan

United Kingdom   
Joined: 23/07/2014(UTC)
Posts: 4,545
Location: ENGLAND, Didcot
Originally Posted by: husafreak Go to Quoted Post
...And of the 3 sets of replacement brushes I bought two of them came with a broken brush in the package. The brush material "coal" breaks at the point where it is stressed passing through the spring steel. One of the brushes on a new loco had broken at the tip creating a chisel shape, another was protruding from the spring at an odd angle. In conclusion I had 4 unusable brushes out of 8. That includes the set in the loco.


Take a photo of them and email service at Marklin and complain. They will probably send you new sets free of charge.

Complaining about such things is about the only way they are going to improve their quality control.



Offline husafreak  
#12 Posted : 07 July 2019 17:54:42(UTC)
husafreak

United States   
Joined: 09/04/2019(UTC)
Posts: 72
Location: California, Bay Area
I would hope my dealer is letting them know, but yes they should be aware.
Offline Poor Skeleton  
#13 Posted : 07 July 2019 22:06:06(UTC)
Poor Skeleton

United Kingdom   
Joined: 09/10/2015(UTC)
Posts: 123
Location: England, Cambridge
Originally Posted by: husafreak Go to Quoted Post
Thanks for posting, I have been following with interest and hoping for the best. I guess I got lucky as all of my Marklin loco's are running well now. But it took a lot of redo's on some, just disassembling and reassembling, playing with clearances, etc..


I guess it also depends upon what you expect and what you regard as running well. The problems as I see them occur at low to medium speed - now I am aware of the issue I'm very attuned to the sound of the motor not keeping constant revs! Of course I don't expect really slow running, with a "traditional" controller, anyway!

Seems you've had much better success curing the problems that I have, though - just about everything I've tried seems to have made matters worse rather than better!

Cheers


Chris
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