Have an MTH motor that has so far confounded me. It was running before I got it.  Runs great in reverse but locks up in forward. Does not have excess bearing slop. If I power it up in forward and force the wheels it will run. It a bit slower and a lot noisier than in reverse. It turns freely by hand, the lock up is when powered. Side rods have been removed so that’s not an issue. Still playing, but looking for advise. 

Steve

Steve "Papa" Eastman

Yorba Linda, CA

Left Coast, Home of the lunatics

Original Post

Sounds like a phasing issue. make sure that the power to field coil to brush1 thru comm to brush2 to ground is intact.  Sounds like its power to brush first and this causes electromagnetic cogging  (lock up) and poor running.

Prewar Tin...Any maker, any gauge, anytime!

Rob English posted:

Sounds like a phasing issue. make sure that the power to field coil to brush1 thru comm to brush2 to ground is intact.  Sounds like its power to brush first and this causes electromagnetic cogging  (lock up) and poor running.

Rob

I sent you an email.

Steve

Steve "Papa" Eastman

Yorba Linda, CA

Left Coast, Home of the lunatics

They have an issue with proper centering of the armature in the field.  Somewhat difficult to fix.  Sometimes the armature laminations are offset, so I chuck the armature in my lathe and turn it down so the laminations are even.  If they are evan and it binds, turning the laminations down will sometimes give it enough clearance so it won't bind in that direction.

Jon G TCA 95-41020

Independent Lionel Service Tech

MTH Service Technician at MTH

Jon G posted:

They have an issue with proper centering of the armature in the field.  Somewhat difficult to fix.  Sometimes the armature laminations are offset, so I chuck the armature in my lathe and turn it down so the laminations are even.  If they are evan and it binds, turning the laminations down will sometimes give it enough clearance so it won't bind in that direction.

That what it sounds like to me. I had a Flyer GP7 which either ran hot or not at all. Once I got the armature centered within the field, it ran (and still runs) quite nicely.

Mark in Oregon 

Why would it directionally bind with "offset laminations"?  Better to correct this centering issue at the bearing.  The gap between the field and rotor is important.  Ive never seen an MTH motor with this issue....other issues, yes.

Prewar Tin...Any maker, any gauge, anytime!

Slightly off-topic, and maybe a dumb question.  But how are the laminations affixed to the armature shaft?  Is it possible to "skew" them, to reduce cogging as they pass through the node between poles?

Creep, coast, and pull.  We're not talking about cold fusion here.

Tinplate Art posted:

Anyone aware if there have been any KNOWN "bad batches" of these received from the sub-contractor?

I have been buying up the traditional BAL motors from MTH. Have had issues with a couple (you wonder whether they just put the problem children back on the shelf). I have had to turn the armatures on a couple because the laminations were not even - I suspect the punch tooling was wearing out and the Chinese just say, 'Power on, motor turns, in the box - done'.

Had one where the bracket the holds the spur gears (and is peened into the side plate), was significantly loose, the motor would run fine in one direction only.

When you are building locos that require 2 of these, and you want to supply new, you work with what you can get - MTH is the only remaining game in town (and will not rerun the traditional motors.

I have a number left to build future Harmon engines.

Jim

Jim Waterman

Lee Lines Limited

Custom Built Standard Gauge

 

Jim Waterman posted:
Steve "Papa" Eastman posted: -

All drivers are now churning both directions.

Steve

Good news Steve - what was the problem (so good to see it running on YOUR layout.)

Jim

Jim

After letting it run longer on blocks, scuff marks began showing up on the stator so it was shifting enough to hit the field. A buddy of mine took it apart and ground the field plates down quite a bit. I'll run it on a loop on the 8th. Can't run it any further at home. I'm really not in the mood to rework the layout

Steve "Papa" Eastman

Yorba Linda, CA

Left Coast, Home of the lunatics

Add Reply

Likes (1)
Post
OGR Publishing, Inc., 1310 Eastside Centre Ct, Suite 6, Mountain Home, AR 72653
330-757-3020

www.ogaugerr.com
×
×
×
×
×