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Offline Donb  
#1 Posted : 27 February 2021 17:49:42(UTC)
Donb

Canada   
Joined: 03/04/2013(UTC)
Posts: 164
Location: Fraser Valley
Hi all,

I recently took delivery of the new 39227 E94 loco.
In the past I've had success getting these DCM drive locos to operate quietly, but this one is proving to be quite a challenge.
Out of the box it was buzzing loudly, the old pepper grinder sound. I ran it like this for several hours to break it in, and then I decided to open it up and see if I could improve it.
One at a time, I replaced the armature, the motor shield, and the permanent magnet. None of these changes made any difference. When disassembled, the gearbox
Is very smooth and quiet when rolled along the table. Once the armature is installed, it buzzes loudly.
So there appears to be an issue with the armature pinion gear and the primary gear in the gearbox. I applied some grease to the gears to try to get them to operate quieter under load, but this had no effect.
Sometimes in the past I've had success by adjusting the motor shield alignment, but there are locating pins on the permanent magnet which prevent this.
I have some spare permanent magnets, I could maybe take one and grind off the motor shield locating pins.
Perhaps the experts here will have some other suggestions?
Best Regards,
Don
___________________________________________________________________________________
Commander , MS2, C track
Offline ocram63_uk  
#2 Posted : 27 February 2021 20:13:18(UTC)
ocram63_uk

United Kingdom   
Joined: 07/01/2015(UTC)
Posts: 438
Location: England, Suffolk
I'm no expert but if the loco is new as you state, send it back !!
I don't uderstand people that spend what they spend for a new loco and this does not conform to their expectations.
Obviously with your tweaking you have void the warranty.
I feel for you, but I would have sent it back immediately. I hope you got it in Canada and not from Europe !!
Have a better week end :-)
Offline Donb  
#3 Posted : 27 February 2021 23:20:13(UTC)
Donb

Canada   
Joined: 03/04/2013(UTC)
Posts: 164
Location: Fraser Valley
Originally Posted by: ocram63_uk Go to Quoted Post
I'm no expert but if the loco is new as you state, send it back !!
I don't uderstand people that spend what they spend for a new loco and this does not conform to their expectations.
Obviously with your tweaking you have void the warranty.
I feel for you, but I would have sent it back immediately. I hope you got it in Canada and not from Europe !!
Have a better week end :-)


I've always enjoyed taking things apart, something that has carried over from when i was young lol.
DCM locos are fairly simple , usually with a minor tweak or bit of oil they can be made to run quite quietly.
CHEERS!
Best Regards,
Don
___________________________________________________________________________________
Commander , MS2, C track
Offline JohnjeanB  
#4 Posted : 28 February 2021 01:43:22(UTC)
JohnjeanB

France   
Joined: 04/02/2011(UTC)
Posts: 1,432
Location: Paris, France
Hi Don
If you cannot return the new loco, on a DCM motor, a loud operation may come from:
* worn or improperly cut gears
* the magnetic armature/magnet is too close / touching the rotor

Both may happen on a new loco if tooling is improperly adjusted / worn out
The rotor hitting the stator is easy to cure, while improperly cut gears need replacing.
But I agree, usually a make commissioning test to verify the item is good for me to keep. (Sorry a bad habit from my job as Engineer and Program Director).
Note on some locos, the operating noise is amplified by a bell effect (my streamlined DB BR 03 by Märklin) which may be reduced but adding small foam pad between the frame and the chassis.
My BR E 94 (39223) is very smooth and silent but it is a sinus motor. It was made in 2004.
39223 BR E 94 Inside.jpg

Before the commissioning test is passed, I don't open or do anything to allow me to return the good.
Cheers
Jean
My layout videos
latest vid
hump yard
thanks 2 users liked this useful post by JohnjeanB
Offline Donb  
#5 Posted : 28 February 2021 02:03:41(UTC)
Donb

Canada   
Joined: 03/04/2013(UTC)
Posts: 164
Location: Fraser Valley
Originally Posted by: JohnjeanB Go to Quoted Post

The rotor hitting the stator is easy to cure,


Hi Jean,

What is the method to cure the rotor from hitting the stator. That might be the problem.



Best Regards,
Don
___________________________________________________________________________________
Commander , MS2, C track
thanks 1 user liked this useful post by Donb
Offline DTaylor91  
#6 Posted : 28 February 2021 03:41:20(UTC)
DTaylor91


Joined: 31/08/2007(UTC)
Posts: 392
Location: Kennesaw, GA
Originally Posted by: Donb Go to Quoted Post
Originally Posted by: JohnjeanB Go to Quoted Post

The rotor hitting the stator is easy to cure,


Hi Jean,

What is the method to cure the rotor from hitting the stator. That might be the problem.





I'm no expert on this, but I would be looking at the inside of the field magnet for a "shiny spot" that indicates where the rotor is hitting, if that is indeed the case. I would also look at the rotor, and check it to see if one of the laminations shows signs of rubbing as well. At the very least, I would be checking to rotor for burrs, and well as the gear attached to the rotor.

For the stator, I would consider wrapping sandpaper (The fine grit type designed for sanding metal. Lots of modelers cut it up and use it to model asphalt paving) around a dowel and cleaning up the inside of the stator. Good luck getting the shavings off unless you can safely remove the magnet. For the rotor, I'd gently rotate it against a belt or disc sander with fine grit. (I tell a lie, I'd use my Dremel tool for both jobs, but this can be tricky). To de-burr the gear, I'd use a flat jeweler's file.

Does the mechanism roll quietly without the rotor in place? If not, there are other issues.
thanks 1 user liked this useful post by DTaylor91
Offline Donb  
#7 Posted : 28 February 2021 06:19:53(UTC)
Donb

Canada   
Joined: 03/04/2013(UTC)
Posts: 164
Location: Fraser Valley
Originally Posted by: DTaylor91 Go to Quoted Post

I'm no expert on this, but I would be looking at the inside of the field magnet for a "shiny spot" that indicates where the rotor is hitting, if that is indeed the case. I would also look at the rotor, and check it to see if one of the laminations shows signs of rubbing as well. At the very least, I would be checking to rotor for burrs, and well as the gear attached to the rotor.

For the stator, I would consider wrapping sandpaper (The fine grit type designed for sanding metal. Lots of modelers cut it up and use it to model asphalt paving) around a dowel and cleaning up the inside of the stator. Good luck getting the shavings off unless you can safely remove the magnet. For the rotor, I'd gently rotate it against a belt or disc sander with fine grit. (I tell a lie, I'd use my Dremel tool for both jobs, but this can be tricky). To de-burr the gear, I'd use a flat jeweler's file.

Does the mechanism roll quietly without the rotor in place? If not, there are other issues.


Hi,

The gearbox rolls quietly without the armature in place.
When I had the motor apart I recall looking at the OD of the armature and the bore of the magnet and didn't notice any obvious rubbing marks. Ill take it apart again and have a better look.

Best Regards,
Don
___________________________________________________________________________________
Commander , MS2, C track
Offline JohnjeanB  
#8 Posted : 28 February 2021 11:38:47(UTC)
JohnjeanB

France   
Joined: 04/02/2011(UTC)
Posts: 1,432
Location: Paris, France
Hi Don
Originally Posted by: Donb Go to Quoted Post
Hi Jean,

What is the method to cure the rotor from hitting the stator. That might be the problem.

Normally you should be able to slide a thin paper between the armature and the rotor.
If you can't then the armature needs to be moved or be corrected:
* MOVED: sometimes there is a little play between the armature and the bogie chassis. So it is about finding the correct position where there is no contact with the rotor.
* CORRECTED: the other possibility is that the location holes for the armature are not exactly where they should (1/10th of mm). Then it is about finding where the contact takes place between the rotor and armature. Then it is about removing a very little metal around the contact point. The best is to use one drum sandpaper that mounts on a Dremel-like hand tool.

Normally only a very little needs to be removed.

Don't do anything on the rotor: it is fragile and could come out of balance (creating vibrations.

Remove thoroughly all metal residues.

Note: gears without strain are usually not loud but may become when they transmit force.
Cheers
Jean


My layout videos
latest vid
hump yard
thanks 1 user liked this useful post by JohnjeanB
Offline ocram63_uk  
#9 Posted : 28 February 2021 17:15:50(UTC)
ocram63_uk

United Kingdom   
Joined: 07/01/2015(UTC)
Posts: 438
Location: England, Suffolk
@johnjeanB this method applies to all motors that present this problem?
Offline JohnjeanB  
#10 Posted : 28 February 2021 18:33:22(UTC)
JohnjeanB

France   
Joined: 04/02/2011(UTC)
Posts: 1,432
Location: Paris, France
Originally Posted by: ocram63_uk Go to Quoted Post
@johnjeanB this method applies to all motors that present this problem?

No, it applies only to "coffee-grinder" (standard Märklin DC motors) not to CAN motors or SDS or C sine motors (obviouslyBigGrin ).
It happened to me only a couple of times on a large number of modified locos.
Also on old locomotives (almost brand new but made in 1980) the gear may be very noisy because of very poor tolerances
Jean

My layout videos
latest vid
hump yard
Offline Donb  
#11 Posted : 01 March 2021 00:53:29(UTC)
Donb

Canada   
Joined: 03/04/2013(UTC)
Posts: 164
Location: Fraser Valley
Hi,

I inspected the armature OD and the magnet bore and didn't see any sign of rubbing wear.
I checked the clearance with the paper feeler gauge per Jeans suggestion, no issue.

So I decided to take out my spare magnet and grind off the Motor Shield (MS) locating pins to allow me to adjust the armature alignment a bit. This gives about 1.0 mm total play, abt .5mm each side, due to the clearance in the MS bolt holes.
I found that when the MS was pushed to the lower left (loco standing, facing the MS) then tightened, the motor noise was somewhat reduced.
I'm thinking this may have slightly reduced the clearance of the Armature pinion gear/primary gear, perhaps less slop, less noise?

Its not perfectly quiet, but now I can hear the sound decoder Motor sound over the 'coffee grinder ' sound, and not vice versa.

I am otherwise very happy with this model, she accelerates and decelerates very smoothly. I really like this Crocodile.

Thanks for the suggestions!
Best Regards,
Don
___________________________________________________________________________________
Commander , MS2, C track
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