need help with an old open frame motor

[Anonymous]

I have an old brass KMT engine with an open frame motor. I have cleaned it and fixed a few windings. The motor still runs intermittent at best. Can someone offer some help?

[Anonymous]

It probably is a three-pole-three different windings or poles on the armature. Newer motors are at least five-pole resulting in smoother starting and fewer dead spots. My only other suggestions are to clean/poli***he armature where the brushes make contact and replace the brushes and the tension springs as a set. Then be sure and give the new brushes time to run in making good contact. You should not have alot of arcing or sparks around the brushes.

[cjcrescent]

Dogwood;
My advice is to replace the motor. The old KMT models are very good models but their original motors were never very good. I think the material the magnets are made of looses its "charge" of magnetism over the years, and the result is a motor that runs hotter than it should. This in turn can cause the insulation on the windings to crack and have bare wire touch. This causes intermittant shorts and the erractic behavior of the motor.

[Big_Boy_4005]

QUOTE: Originally posted by cjcrescent

Dogwood;
My advice is to replace the motor. The old KMT models are very good models but their original motors were never very good. I think the material the magnets are made of looses its "charge" of magnetism over the years, and the result is a motor that runs hotter than it should. This in turn can cause the insulation on the windings to crack and have bare wire touch. This causes intermittant shorts and the erractic behavior of the motor.

I'm with CJ here on this one. If at all possible, replace that motor with a modern "can" motor. Is the model in question intended to run on AC? If so, it makes that replacement a little trickier, but not impossible. Can motors have a lot of advantages over open frame, they are quieter, smoother, and use less current to operate. The problem is they need DC to operate.

[Virginian]

While you could probably get it rewound, I would advise replacing it. NWSL is the place to check. Motors, gears, axles, etc.; they're the guys.

[mcouvillion]

dogwood960,

If you are interested in trying to repair the motor,even if it is just an exercise to see if you can do it, check the end-play of the armature. Usually there is a lot of slop in older motors, such that they run well in one direction and not the other. Try to take the slop out by using the Kaydee 0.010" or 0.015" shims. Cut a "V" into the side of the shim such that it can slip on the armature shaft but won't slip off. Pu***he slop out of the armature such that the brushes track down the center of the commutator. Install the shim(s) in the gap at the end of the armature inside the motor frame. The armature must turn freely, but with minimal end-play. Lubricate the armature at the journals and run it in on the bench, both directions and varying the speed. You should get it to eventually run smoothly at very slow speeds in either direction. You'll also want to poli***he commutator when you have the brushes out while you are working on the motor.

I offer this suggestion because it is easier to get the original motor to fit, if you can get it to run properly, than it is to figure out how to properly install and align a new can motor. My LHS rep suggested that I use silicon adhesive to install my new can motor in my TrainMaster. NEVER! The motor had four threaded mounting holes and I found 4 tiny screws that fit and built new mounting brackets. Took days to get everything right. If I can use the original motor, I will always use the original motor, but I'll make it run properly first.

Mark C.

[areibel]

Originally posted by mcouvillion

dogwood960,

My LHS rep suggested that I use silicon adhesive to install my new can motor in my TrainMaster. NEVER! The motor had four threaded mounting holes and I found 4 tiny screws that fit and built new mounting brackets. Took days to get everything right.


Mark,
I've used the black RTV silicone to mount motors in several locos, it makes it a piece of cake! Have you had a specific problem?? It seems that the hassle of trying to get everything drilled and aligned to use screws would be a very un- fun thing to do!

Cambridge Springs- Halfway from New York to Chicago on the Erie Lackawanna!

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