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Discussion Starter #1
I have a question. Why do some of my Locos run faster in reverse? In particular, I have two AF 290's that I rebuilt in accordance with Dave's AF trains Videos. I followed every step. Cleaning, polishing, lubrication, new fingers, finger tension, new brushes, brush springs, brush spring length at least 1", polished & cleaned commutator and grooves, Checked continuity, Isolated E Unit, and one 290 runs perfect in both directions and the other runs faster in reverse. I have noticed this with other locos I have as well. Do some motors run faster in different directions. I've dismantled this loco so many times I can do it blindfolded.
 

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It's not an uncommon problem for some engines. PortLines has a clinic on their website that addresses the most common issues that may be the cause. You can eliminate some of the tips if you've already done those and zero in on the other tips you may not have done. Here's a link. Hope this helps. http://www.portlines.com/portlinesclinic20.htm
 

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The idea here is to implement carefully all the cleaning, adjustments and repairs in the clinic. That does not always mean the engine will run at the same speed in both directions. Gilbert made many running changes to the design of their armatures. These changes included among other things the winding direction around the poles (clockwise v counterclockwise) and the position of the commutator slots with respect to the poles. These features affect torque and speed in each direction differently. With the advent of PulMor Gilbert needed greater starting torque and increased armature heat buildup resistance since the motor could stall rather than have wheels slip as w/o PulMor. Changing the position relationship of the commutator slots to increase forward starting torque would reduce forward top speed; it does the opposite when the motor rotation direction is reversed. The large motor was also developed for these reasons.
 

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I have a question. Why do some of my Locos run faster in reverse? In particular, I have two AF 290's that I rebuilt in accordance with Dave's AF trains Videos. I followed every step. Cleaning, polishing, lubrication, new fingers, finger tension, new brushes, brush springs, brush spring length at least 1", polished & cleaned commutator and grooves, Checked continuity, Isolated E Unit, and one 290 runs perfect in both directions and the other runs faster in reverse. I have noticed this with other locos I have as well. Do some motors run faster in different directions. I've dismantled this loco so many times I can do it blindfolded.
Re-face the armature..Cleaning and polishing alone won't cure the problem.. By re-facing the armature, you remove any small microscopic grooves on the face of the armature, truing the surface.
 

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When I first got my 336 it ran same speed forward or reverse. Now forward is faster than reverse. I suspect one of the wires to the plug. They are stranded wires and if some of the strands are broken you will not get full power from that wire.
 

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Discussion Starter #6
Thank you all for your advise. I am going to follow the Portline Repair clinic outline. I have aligned the smoke rod stud aft and the side rod studs forward. No change. Next I checked to see if the axle gear was centered properly. It was. Next I checked the smoke piston gear. Not sure what firmly mounted means. The gear has play in it. I'm sure it has to have some play and I don't like the idea of driving that stud into the smoke gear. Do you drive from the stud side or gear side? I have also noticed some play in the chassis and brush bracket bearings. Maybe that's the problem? The commutator appears to be pretty smooth, but that will be my last resort.
 
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