Thread: Drill Motors and HEAT!
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Unread 24-06-2002, 00:02
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#0047 (ChiefDelphi)
  
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Re: differences in friction still seems more likely...
Posted by Brian Cholerton at 2/5/2001 9:56 AM EST


Engineer on team #311, Red Jammers, from East Islip High School and KeySpan Energy, Multiline Corp., Computer Assoc..


In Reply to: differences in friction still seems more likely...
Posted by Joe Johnson on 2/3/2001 4:52 PM EST:



: It is possible that the fans are more effective in one
: direction than another (though I have never seen a
: Johnson Electric or Mabuchi spec that mentions this),
: but I still think that it is much more likely that
: differences in friction between the two drive trains is
: the culprit.

I agree that drive train friction is more than likely the main reason for heat buildup in the motors. Especially when they are used in this application.

One other item that may be adding to the heat buildup in the motor rotating "backward" is the timing of the commutator. DC electric motors are designed to make maximum power, or efficient use of power when rotating in one direction. The cummutator is timed in relation to the magnetic field to achieve this. If the polarity is reversed the motor will still run but will not be as efficient which will result in additional heat buildup.

Just my 2c worth based on a few years of racing slot cars and tinkering with much smaller motors.


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