Trains.com

Poor MPC U36B operation

4610 views
16 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    December 2011
  • 15 posts
Poor MPC U36B operation
Posted by NYC20 on Wednesday, January 25, 2012 11:38 AM

I found on YouTube an MPC U36B that seems to have exactly the same problem that mine has.  Maybe worse.
If CTT removes the URL it can be found by searching on YouTube for "Trem Lionel Santa Fe 8755".
The operator has to cycle the e-unit several times before it will move forward.  The intensity of the cab light indicates that he has to crank up the voltage just to get the motor to start moving.  Then when it does run it is rather slow and makes a grinding noise.  Mine is very similar.
When my U36B was new it had no such grinding noise and if I had started it with track voltage as indicated by this cab light, it would shoot forward and probably jump the track at the first curve.
I have removed the brush plate, cleaned the commutator and brushes, and done all the cleaning and lubricating that I can to the pinion and gears, all to no avail.  Something is worn, I suspect the pinion or worm drive on the armature shaft.
Has anyone fixed a problem like this?

Tags: Lionel
  • Member since
    October 2011
  • 969 posts
Posted by TrainLarry on Wednesday, January 25, 2012 6:07 PM

  Get a good , close look at the e-unit. Inspect the contact 'fingers' to see that they have enough tension, are making good contact with the drum, and that they are not worn or pitted. Inspect the drum to see that it also is not worn or have burn marks on it. Replace contacts and / or drum as needed.

 Make sure that the armature shaft bearings and axle bearings have been cleaned and are lubricated also.

Larry

  • Member since
    April 2007
  • From: MICH
  • 8,153 posts
Posted by sir james I on Wednesday, January 25, 2012 7:15 PM

Check the brushes and the springs. I would replace them. Another common problem with this motor is it requires a small bit of lube on the upper shaft, check the up/down motion of the armature, it should just be loose enough to turn freely..

"IT's GOOD TO BE THE KING",by Mel Brooks 

  Charter Member- Tardis Train Crew (TTC)   - Detroit3railers-  Detroit Historical society Glancy Modular trains- Charter member BTTS

  • Member since
    December 2011
  • 15 posts
Posted by NYC20 on Wednesday, January 25, 2012 8:07 PM

Thanks.  I have removed the brush plate and armature and cleaned and lubricated everything.  I don't think it's an e-unit contact problem.  The drum looks just fine.  If I slowly increase track voltage, at about 80% of max suddenly it appears that something shifts or kicks in and the grinding sound stops and it takes off like new, sounding like new.  A guy who says he has repaired a lot of these MPC locos says the armature probably is not positioned just right and that he has fixed a lot of these locos with this problem.  These MPC motors were manufactured poorly with tolerances not fine enough.  That makes sense, if the armature shaft bearing in the brush plate is worn that would explain it.

  • Member since
    December 2005
  • From: Hopewell, NY
  • 3,233 posts
Posted by ADCX Rob on Wednesday, January 25, 2012 8:12 PM

The armature is dry.  Lube(and I mean with grease - Lucas Red 'N' Tacky #2 or another extreme HP synthetic lithium based grease) the worm, the worm wheel, and the top of the armature(small dollop in the well below the set screw) and use a very thin coating on the spur gears.  With synthetic oil, lube all shafts, bearings, & bushings sparingly.

The Lucas will take up some slop in the armature if it is worn to that point.

Rob

  • Member since
    December 2011
  • 15 posts
Posted by NYC20 on Wednesday, January 25, 2012 8:15 PM

Thanks.  Brushes look quite good and the springs are quite strong. I have removed the brush plate and armature and cleaned and lubricated everything.  I would like to check the up/down (and lateral) motion of the armature but it is nearly completely inaccessible when the motor is assembled.  I can poke a toothpick through the brush holes to the commutator and that's about it.  I can turn the wheels and watch the gears and it feels as though there MIGHT be too much up/down motion in the armature, but when I do the same thing with my brand new 2344 NYC Conventional Classic it feels exactly the same.  If I slowly increase track voltage, at about 80% of max suddenly it appears that something shifts or kicks in and the grinding sound stops and it takes off like new, sounding like new.  A guy who says he has repaired a lot of these MPC locos says the armature probably is not positioned just right and that he has fixed a lot of these locos with this problem.  These MPC motors were manufactured poorly with tolerances not fine enough.  That makes sense, if the armature shaft bearing in the brush plate is worn that would explain it.

  • Member since
    December 2011
  • 15 posts
Posted by NYC20 on Wednesday, January 25, 2012 8:21 PM

Thanks for the Lucas comment.  I did not know that!  I lubed everything with new Lionel lubricant and that did not help.  I have posed what a train repair person told me.  Makes sense, but who knows?  If I can find that Lucas lube I'll try that, although the repair guy did not mention a worn worm.  That was my first guess also as the worm and gear that it drives were dry when I took the armature out. 

  • Member since
    November 2008
  • 227 posts
Posted by nickaix on Thursday, January 26, 2012 5:05 PM

Look at the very top of the protruding part of the brushplate: see if it accepts a small allen wrench. (I want to say, 3/64"?) Some of these motors have a sort of top bearing which can be screwed in or out to govern the vertical play of the armature. Not sure about MPC motors, but our LTI Dash-8s have this.

Does the engine run more smoothly in one direction? With the vertical worm drives, in one direction, the armature is being pulled down into the chassis, and in the other it wants to buck up against the brushplate. If that's what's happening (and if there is no top bearing adjustment) maybe stiffer brush springs will help keep the armature shaft seated properly. Another thing to try would be a TINY bit of grease on the commutator face just where it meets the armature shaft, to smooth things out in case the commutator is riding up on the underside of the brushplate. (I have seen some motors where there is a little metal bushing or washer on the underside of the brushplate here.) Be careful with the grease though, or you could gum up the whole commutator.

  • Member since
    December 2011
  • 15 posts
Posted by NYC20 on Thursday, January 26, 2012 6:21 PM

Thank you, very interesting possibilities.  There is such a peak in the brushplate but I never would have guessed that there could be an adjustment there.  I'll check that plus all your other suggestions.  But I won't have time for a few days.  I'll let you know what happens.

  • Member since
    November 2010
  • 993 posts
Posted by gunrunnerjohn on Friday, January 27, 2012 9:08 AM

Under that setscrew, there is a ball bearing that rides between the screw and the armature.  You should put a drop of oil in there, then tighten down the setscrew until there is just a very small amount of up/down play in the armature when you try to move the wheels forward and backwards.

 

  • Member since
    December 2011
  • 15 posts
Posted by NYC20 on Saturday, January 28, 2012 6:31 PM

gunrunnerjohn, There is a screw there adjustable via allen wrench.  My set goes from .036 (too small) to .05 (too large) so I'll have to find something in between.  Your estimate of 3/64, which is .0469, just might be right on.  Maybe I'll get to this tomorrow.  Thanks!

  • Member since
    February 2004
  • From: Rolesville, NC
  • 15,416 posts
Posted by ChiefEagles on Sunday, January 29, 2012 9:00 AM

After you get the motor right, add a few oz.s of fishing weights [lead] to make it get better traction.  I use to pull the fuel tank and put them in there.  I use to take three, weight them and tether them together to one E unit.  Really pull then.

 God bless TCA 05-58541   Benefactor Member of the NRA,  Member of the American Legion,   Retired Boss Hog of Roseyville Laugh,   KC&D QualifiedCowboy       

              

  • Member since
    December 2005
  • From: Hopewell, NY
  • 3,233 posts
Posted by ADCX Rob on Sunday, January 29, 2012 9:44 AM

If weight is desired, try these "tape-a-weights"(we used to call them) available at Harbor Freight:

Rob

  • Member since
    February 2004
  • From: Rolesville, NC
  • 15,416 posts
Posted by ChiefEagles on Sunday, January 29, 2012 10:53 AM

ADCX Rob

If weight is desired, try these "tape-a-weights"(we used to call them) available at Harbor Freight:

http://i40.tinypic.com/m9aw4x.jpg

Rob, thanks for the "heads up" on those weights.

 God bless TCA 05-58541   Benefactor Member of the NRA,  Member of the American Legion,   Retired Boss Hog of Roseyville Laugh,   KC&D QualifiedCowboy       

              

  • Member since
    December 2011
  • 15 posts
Posted by NYC20 on Tuesday, January 31, 2012 12:35 PM

nickaix, thanks a million!!! This fixed it!  I happened to have 2 identical tool kits, each with 2 small allen wrenches, .05 (too large) and .036 (too small).  3/64 is about .0469 so you were right about that.  I couldn't find a 3/64 anywhere, except online for about $9, so I finally got smart and filed one of the .05's down until it would just fit.

I was suprised at how far I had to turn the screw, and then that there seemed to be an optimal point for best operation -- not too loose, not too tight.  But now it's as good as new.  Wow, thanks again!

  • Member since
    November 2008
  • 227 posts
Posted by nickaix on Tuesday, January 31, 2012 3:03 PM

You're welcome! glad I could help! Big Smile

  • Member since
    December 2011
  • 15 posts
Posted by NYC20 on Tuesday, January 31, 2012 4:15 PM

Hi ChiefEagles, thanks for the idea.  Even with the motor fixed, this runs out of power before traction is a problem.  It will pull about 15-20 MPC freight cars with ease and that's about all I ever do with it.  I bought it new 30+ years ago when my sons were toddlers so it has some sentimental value.  I put a light in the dark end.  I think it looks great buzzing around the track.  Linking 3 of them together must give a lot of power.  I use my twin-motor F3's for serious hauling.

Join our Community!

Our community is FREE to join. To participate you must either login or register for an account.

Search the Community

FREE EMAIL NEWSLETTER

Get the Classic Toy Trains newsletter delivered to your inbox twice a month