# Forward speed versus reverse speed



## rrswede (Jan 6, 2012)

I am assisting a young man get his father's AF 21085 4-6-2 locomotive operating after sitting for some years. Being quite familiar with pre and post war Lionel locomotives, I expected the AF locomotive to run faster in forward than in reverse. This locomotive does just the opposite. Is this a quirk or common?

The unit has been fully serviced and it was not necessary to do any rewiring.

Thanks for you thoughts. 

swede


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## flyernut (Oct 31, 2010)

It's the same old problem with AF.. Did you re-face the armature?? The problem is the loco has been running in forward all these years and sometimes in reverse. A micro-scopic groove has been worn into the armature's face and must be removed. To do this you must re-face the armature.I remove the armature from the chassis and chuck the armature shaft into my drill press. Spinning the armature, I hold a piece of sand-paper against the face and "flatten" out the surface of the armature...400 grit paper seems to work for me. I then use 2000 grit paper and polish the face..


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## rrswede (Jan 6, 2012)

Thank you for responding, flyernut. 

I did not resurface the facing, but thoroughly cleaned it and the brushes before reassembly. The facing had wear but no grooves and the brushes had little wear and were smooth.

Since my experience is that older Lionel parallel plate motors run faster in forward than reverse, I felt the reason was less gear facing friction from running in forward most of the time. I do not recall noticing this phenomenon with the Lionel worm drive motors but have far less experience with them.

I am still puzzled why a AF worm drive motor would turn at a faster rate in reverse as opposed to forward due to commutator plate grooves. You have tons more knowledge than me so I will take your advice and more closely check the commutator.

Thanks, again,

swede


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## mopac (Feb 24, 2011)

Very hard to argue with flyernut. I call him my AF guru. And he is probably correct.
But I will give you another possibility. The wires that plug into back of engine are
stranded wire. One works for forward and one for rearward. If a few of those strands
are broken it just won't carry as much juice. I have an AF engine right now that I need to redo one of the wires. This engine was running fine in forward and reverse and all of a sudden it now runs fine in forward but is about 1/2 speed in reverse now. I think it is one of the wires. Just something else to look at. This can happen to forward or reverse.


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## AmFlyer (Mar 16, 2012)

Flyernut is addressing a commutator wear pattern that occurs on all steamer commutators. Until it is resurfaced the engine will not run as fast forward as reverse. However when he does the resurfacing he has already identified and fixed other common issues with steamer motors. Look at Repair Clinic #20 on the PortLines web site for a complete list of items that can require attention.


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## rrswede (Jan 6, 2012)

Thank you for the additional responses. Mopac and AmFlyer. 

After reviewing the material AmFlyer referred me to as well as your hint, Mopac, I removed the motor from the shell, again. After unsoldering the various wires, that look good, the armature and brushes were removed. Particular attention was paid to the condition of the commutator face that looked very good. I did lightly resurface it. It is clean, bright and smooth. The armature has one washer on the armature gear shaft and one on the commutator shaft. After reassembling the motor, I checked for front to back armature movement. There is between 1/32" -3/64" movement. See attached photo. I don't think that is excessive. What do you think?


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## AmFlyer (Mar 16, 2012)

That sounds ok to me as long as there is no binding at either extreme of movement.


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## rrswede (Jan 6, 2012)

After AmFlyer's last response, I put power to the locomotive and experienced the same condition as before. Today, the motor was disassembled again and a second shim washer was placed on the gear shaft. Now there is a bit more than 1/64" end play and the armature turned freely by hand. When power was applied, the motor acted just as it had previously. 

Rather than disassemble the motor again, removing the second shim from the gear shaft and placing it on the commutator shaft for a different test, I assembled the entire locomotive, took it to the owner's home and ran it on his track. It ran plenty fast for him and he was satisfied with it as is. Now I'm wondering if one more try would have solved the issue. Was hoping for total success.

Thanks everyone.

swede


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## cramden (Oct 13, 2015)

If the owner is happy, then you did what you could. I'm curious about the motor since all of the 21085 engines I have seen had the drum commutator instead of the flat faced one and the 2 position reverse unit mounted on the back of the motor. Maybe some early ones still used the old style motor and reverse unit in the tender, but I've not seen any.


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## rrswede (Jan 6, 2012)

Cramden, this unit does have the drum style commutator and the reverse unit is attached to the motor. The brushes are contained in a rectangular sleeve with a bent tab on the end to contain the spring and serve as a electrical connecting point.

swede


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## cramden (Oct 13, 2015)

Thanks for the response, I thought they all had the later set up. The square brushes will wear with a curve due to the way they sit against the drum vs. the tube style brushes that wear flat. I have found that sometimes from sitting the motor takes some running to get it back to where it runs about the same in either direction. If your friend is happy, that's all that matters.


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## rrswede (Jan 6, 2012)

The brushes are about 1/4" long from the base to the bottom of the curve. I don't know how long they are when new but they seat against the commutator nicely and there is no sparking when the motor is running.

The only local hobby shop wanted $10 for a pair of new ones and wouldn't have them for a couple of weeks. Since the present ones work I didn't buy them. I'm sure I can find them cheaper even with shipping.

swede


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## cramden (Oct 13, 2015)

You might want to get new brush springs if you going to replace the brushes. $10 is way too much for a pair of brushes.


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## rrswede (Jan 6, 2012)

You're right. ttender has the brushes for $1.75 each. Of course I'll have to buy some more stuff from Jeff to make the shipping cost worth while. Even if I only bought springs and brushes the total would probably not exceed $10.

swede


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## cramden (Oct 13, 2015)

Ask him about the springs, I don't see them listed but he might have them. If not Doug at Portlines.com has them.


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## rrswede (Jan 6, 2012)

The owner also has a rocket launcher missing the rocket. It doesn't look like Jeff carries it either but I know enough to contact him first. 

swede


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## cramden (Oct 13, 2015)

There were repros made so they shouldn't be hard to find, worse case is ebay.


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## dooper (Nov 9, 2015)

They are easy to find. That is why I let my young grandsons play with them unsupervised at Christmas.


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## rrswede (Jan 6, 2012)

I spotted them on Ebay as low as $10 + $3.75 shipping but I'll ask Jeff anyway.

Thanks, swede


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## AmFlyerFan (Jan 27, 2019)

subscribed.


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## flyernut (Oct 31, 2010)

Are these the ones that are square and soldered to a brass arm??? If so, Jeff has them for $4 bucks or so apiece.


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## apoc444 (Jan 28, 2013)

Jeff has the rockets too


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## rrswede (Jan 6, 2012)

Flyernut, these brushes are loose and fit in a rectangular tube. Jeff has them at $1.75 ea. 

apoc, I'll be calling Jeff later this morning west coast time.

Thanks, guys, swede


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