Today I was rebuilding the starter motor for the race car, and noticed that the magnets are retained in an interesting way.
Apart from the usual sheet metal spacers between each magnet, there's actually a very thin tube between the magnets and the armature, which will make sure both the magnets and retainers stay in place under all conditions.
Since starter motors have a hard life, being subjected to harsh vibration and temperature differences, I think this setup must have been found to work pretty well!
The starter motor actually has a very tough looking single stage planetary gear reduction in it too, as well as some very strong bearings on the output shaft.
The actual motor shaft runs on tiny bronze bushings though, so I don't think it would last very long if used as a drive motor for any length of time. _________________ The Engine Whisperer
- fixer of things
Thu Jul 21, 2005 2:52 pm
Nick Experienced Roboteer
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
Wow! That's really interesting, do you have any idea what the thin inner tube is made of? It looks to be metal, but the exact type would be critical to the motor performance. This would work really well if there is enough clearance between the magnets & armature in the Mag motor. _________________ Australian 2015 Featherweight champion
UK 2016 Gladiator champion
Thu Jul 21, 2005 5:11 pm
Valen Experienced Roboteer
Joined: 07 Jul 2004
Posts: 4436
Location: Sydney
its probbly a non ferro magnetic metal
i'd gess aluminium,
you could probbly make one out of titanium nick ;->
you want something that is a poor electrical conductor if possible as the metal will get eddy currents induced in it, so perhaps stainless?
a fiberglass/kevlar version would be good methinks.
the eddy currents probbly arnet a problem in a starter as they typically have power to spare and dont run long enough to get hot (one hopes) _________________ Mechanical engineers build weapons, civil engineers build targets
Fri Jul 22, 2005 10:32 am
DumHed Experienced Roboteer
Joined: 29 Jun 2004
Posts: 1219
Location: Sydney
yeah I think it's stainless steel.
It's certainly stronger than aluminium anyway! _________________ The Engine Whisperer
- fixer of things
Fri Jul 22, 2005 9:32 pm
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