Main motor failure and cure

[John Shipley]

I just took apart a friends SR main motor that had failed. I wanted to see why. What I found was that the motor wires had broken off inside the motor at the stator. Each motor wire is made up of several small wires that are wound around a 9 pole stator. The wires were broken probably from fatigue.....in other words the wires were not tied down and were moving around untill they finally snapped. The cure for this is to run your motor wires under the battery strap. The wires would be between the strap and the under part of the battery mount. In this way the strap hold the the wires from moving. Think of it this way, if you were to take a metal coat hanger and bend it back a forth for a while, the wire would eventually fatigue and break. This is what happen to the motor wires.....they moved up and down or vibrated untill they failed.
This motor was "clicking" when the battery was plugged in and would not spin. So if any of you have had a motor fail for any reason, I would like to take a look at it and see what the cause is. Just PM me for my address.......J

[SeanM]

Great info J.. I have mine zip tied in certain areas that prevents it from moving much, but I never thought about running them through the battery straps. I'm going to make that change right now.. Thanks for the tip!

[SYMAWD]

Makes sense. When I removed the shrink tubing from my wires on my burnt out motor, the wires were all frayed and no longer "one".

[John Shipley]

S, The wires are not one.....they are multi strand wires that run to different stators and then come together in the insulation. I did not count the strands, but I would guess it was 4-6.....but that would be a good question to answer. These wires are tiny and very fragile. The motor is actualy quite simple. The bell has 6 magnets on it, the stator is 9 poles with stands of wire wound around them and then bound together to form 3 wires that exit the motor. and then there are two bearings in the main frame. In theory it should run forever. These wires are so small and fragile, it is hard for them to support the weight of the 3 motor wires together.....J

[kenkadish]

Thanks John...

Ken

[marcoeldragon]

Great post thanks John, definitely something to check and try to prevent.