MPC motor question

In my limited experience with these motors, they are similar to the 200 series Alco motors in the late '50s early 60s locos, the staked areas that hold the field to the truck frame have to be restaked. This requires removing the motor from the frame, position the aluminum side frame of the motor on a vise, and using a chisel and hammer, restake the four places where the motor side frame is attached to the field. I have some success with this, although not anywhere near enough that I would do it to a customer's loco, but am content with the results I get with some of the items I have purchased. The brush plate should have a screw to limit upward movement of the armature, I have used a spacer washer on top of the armature to limit upward travel, with some success. Since you have it apart, grease the  gears with a lithium grease and oil all of the shafts and bushings in the truck. Keep us posted. 

 

Thanks for your reply...

 

I'm not sure I follow you on the staking ?

 

Any brands of grease and oil recommended ?

 

Where would I find more information on learning about this ? 

 

I've seen a lot of repair books out there, but I 'm not sure which one would would be the best regarding MPC era trains (which is all I have)

 

I have rebuilt one of these motors before. Here are some pointers- 1. Check if there is a lot of carbon "soot" built up on the commutater or armature. 2. There should be tiny wire-like strands coming off the top of the armature. They kind of swoop down and back up. If these are disconnected or "crispy", the armature was overheated and "burned" the motor. 3. Is the e-unit triggering on dead spots causing it to "float" between forward and reverse? If you can eliminate these issues, it could be a much more serious problem. Also, on the top pole of the armature there is usually a stack of tiny washers between the armature and the brushplate. Also, any plastic compatible grease works well in these motors. Finally, on some of my ALCo's, there is some give to the drive axels and gears and they run fine. Hope this helps! Adam

There was a fair amount of soot on the armature. 

 

The wires were fine. 

 

The e unit has been working fine, but as time has went on in the last few months  the engine has just required more power to maintain forward speed with it finally set to wide open to get it moving to what would have been 1/4 throttle...

 

 

Might have a stripped drive gear? Usually a bit of lube and they run so fast they could fly off the track. I am thinking an overheated motor, just because it seems to be getting progressively worse.

It could just need the soot cleaned up. (Not sure why it cut this sentance off) Hope you get it running!

The motor and gears look pretty dry.  Full lube job is in order. Oil(LaBelle 108, Mobil 1, or another full synthetic) on all axles,  synthetic HP grease on gears(Lucas Red 'N' Tacky #2 or similar).  I use the tiniest swab/wipe of grease in the brushplate for the armature - it does not throw out like oil.  Same at the bottom of the armature - I let it ride completely on a film of HP grease.

 

Take up any end play in the armature to about 1/16".  This will keep the brush tension even in both directions.

 

The motor appears to be in too good condition to need any re-staking at this point. 

 

You can true the brush surfaces with emery cloth on a flat surface before re-installing.

 

 

To take up the play in the armature do I just add a washer or do I need a bearing or something between the set screw and the armature shaft ?

 

 

Thanks

Adjust the screw.  Unlike some pre-1970 motors, there should be no washers on top of the armature.

quote:

In my limited experience with these motors, they are similar to the 200 series Alco motors in the late '50s early 60s locos, the staked areas that hold the field to the truck frame have to be restaked.

 

I have yet to run across an MPC motor that needed restaking.

The Postwar Lionel motors that often require the restaking are those that use a little plastic plate on the bottom of the engine for the lower armature Bearing.

The MPC Alco / Geep style motor do have their lower armature bearing in the same place, but the design of the lower bearing is very different.

 

As Rob wrote, the setscrew on the top of the motor probably needs adjusting. I like to carefully tighten the setscrew until the up and down play on the armatur is gone, and then back out the setscrew about 1/2 to 1 turn to put back a little play. There should be a little play.

Some MPC motors had a pointed set screw. I have seen motors where the point wore a matching depression into the top of the armature shaft, creating extra drag.

I usually replace those set screws with flat or cupped ones.

Folks complain about Modern Era Lionel trains having too many plastic parts. I've had a couple of those motors that were so well used that the wheel's gear teeth were worn to points. The plastic idler gears were worn at their center holes. The metal bearings had egg shaped holes, but the plastic bearings showed no signs of wear at all.  (These motors had metal bearing on one side, and plastic on the other.

 

Here is a diagram for the MPC era Alcos made up to 1979.

 

This does not give a breakdown of the motor, but it shows how all the operating parts come together.

 

I've been adding these to the files section of the Lionel MPC Yahoo Group.

 

Ken

The motor breakdown is a seperate page. Here are three versions. (Oops: one is a switcher truck)

Lionel has the entire Modern Era service manual available on their site.

The search function does not work well on older items, so one has to hunt.

 

Thanks for the breakdowns.

 

I found the Alco one but had a hard time finding the motor one...

What Chuck suggest's works for me too. Also lift out the armature and carefully look at the field inside for any rub marks. If there are, that is your problem.

Rob

 

quote:

I found the Alco one but had a hard time finding the motor one...

 

It might take a bit to get accustomed to the organization of the Modern Era manual.

I purchased one before it was available online, and leafed through it. You can download a copy if you wish. Maybe printing the table of contents would be helpful.

(Unfortunately, each suppliment has its own TOC). There are suppliments that consist of nothing more than a re-indexing of the manual, including the suppliments.

 

In addition to all the previous tips, another point to check would be whether the worm gear or the gear on the end of the worm gear shaft are binding in one direction. The action of the worm tends to push the gear / axle assembly to one side, depending on the direction you are running the motor truck. 

If you have the problem, I am certain folks will have a few suggestions on how to fix it.

Well I took everything apart and cleaned and greased, problem is I think I ground too much off the brushes as they are below the spring without enough tension and they spin around, thus not making a good contact.

 

Thanks again for the suggestions, as soon as I get some new brushes I'll post up..

 

I'm learning everyday...