DC Motor Power Explanations

Discussion in 'General Electronics Chat' started by dcronin81, Jul 28, 2013.

  1. dcronin81

    Thread Starter New Member

    Jul 28, 2013
    1
    0
    Hey Guys im new here and im hoping some of you brains can answer my questions. Here goes:

    Im an avid 1/64 scale Slot Car racer and all of the brushed DC motors are rated by Ohms. If the resistance from pole to pole is the same on multiple armatures would all 3 armatures perform the same? These are 3 pole armatures and can be removed and installed in the same motor housing and brush setup to keep the only variable being the armature.


    I have searched thru hundreds of 6 ohm arms and some are plain rockets. All are dynamically balanced within 2 milligrams and the commutators are diamond trued. Aside from all possibilities outside of measuring the OHMs from pole to pole is there a hidden factor that could cause 1 arm to be better then the other?


    PLease educate me.


    DC
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,566
    2,379
    There are many variable to consider, but assuming that the stators are identical and do not vary in P.M. quality/strength etc, and the armatures are obviously all the same diameter and length, they can vary in pole count, also the resistance of the rotor windings are so small, I doubt if you could detect a difference between a rotors that have a winding difference in either gauge or number of turns.
    Quality DC motor usually have skewed lamination's of the rotor, but I doubt if this is done in these type of motor?
    Motors that have weaker field magnets, posses a higher rpm for a given applied voltage, but lower torque O.A.
    Unless the stator magnets are anything but outstanding quality, removing the rotor for any length of time has been known to cause the magnets to loose strength due to the loss of 'Keeper' effect of the rotor.
    Max.
     
    Last edited: Jul 28, 2013
  3. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
    2,812
    834
    Brush quality and spring (if used) strength are also variables. I used to increase the motor speed of 1/87 slot cars by placing a drop of alcohol on the commutator before running. Wahl's Hair Clipper oil is purported to help here, too. The objective is to maintain good contact between clean commutators and brushes during operation.
     
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