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Motor for electric leaf blower

Discussion in 'Electronic Design' started by Andy K, Mar 19, 2013.

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  1. Andy K

    Andy K Guest

    My leaf blower stopped working.

    I tested the switch and it was fine.

    Power is getting to the motor.

    There was a black buildup on the armature, so I sanded it with a 1500 grit sandpaper.

    Now the motor starts but it stumbles.

    Is there anything else I can do or is the motor toast?

    Thanks,
    Andy
     
  2. Respectfully suggest you buy a broom :)
     
  3. Andy K

    Andy K Guest

    Thanks.

    The brushes weren't worn that much but I will clean them up.

    I have replaced brushes on alternators, but this motor has a much faster r.p.m. so it stands to reason that it is gonna wear down much faster.

    Andy
     
  4. Andy K

    Andy K Guest

    Respectfully ignored as poor advice.
     
  5. Andy K

    Andy K Guest

    Thanks for your help.

    Not that I can see with the unaided eye.

    I checked the brushes, and the end is very slightly grooved like it wasn't making a good contact.

    Others I have seen are shiny on the end.

    Should I polish the end and retry it ?

    The motor is only a couple years old.

    I will take a picture and get back.

    Andy
     
  6. Jasen Betts

    Jasen Betts Guest

    clean between the commutator sectors
    replace the brushes.
     
  7. Andy K

    Andy K Guest

  8. P E Schoen

    P E Schoen Guest

    "Andy K" wrote in message
    Try an ohmmeter on the brushes and rotate the shaft. It should alternate
    between two values depending on the position if the brushes are aligned on
    one pair of windings or two. Even better would be to apply a safe, low AC
    voltage (6-12 VAC) and check the current draw. A shorted winding will draw a
    lot more current. You may even be able to feel some torque on the shaft or
    it may try to run slowly, and you may see where it hesitates.

    Or you can grab an obstructionist Republican politician by the feet and he
    will blow away the leaves with hot air :)

    Paul
     
  9. Andy K

    Andy K Guest

    You may have found something.

    Ohmmeter is showing 0 ohms no matter what position the commutator is at.

    What does than mean ?

    Andy
     
  10. Guest

    Brushes worn down so much they do not make contact?

    Dan
     
  11. Jamie

    Jamie Guest

    dose not mean much actually.

    If that is a low voltage motor, something less than 50volts, your meter
    most likely won't read anything useable because the normal readings for
    that motor will most likely be less than an ohm and lots of meters
    just won't display any usable data down there. That is, DMM's that cost
    less than 100 bucks.

    What you should be doing is measure for leakage to ground/core. Any
    reading less than 500k ohms is suspect. If you have a mega meter that
    could be useful, too.

    Also, if it has a PM (permanent magnets)? They maybe weak from heat
    and that is going to cause lots of amps and no torque, but it'll spin like
    hell if you can get it running. Once the magnets start degrading for
    what ever reason, the heat from efficiency loss just exponentially
    degrades the motor.

    I am guessing you may have a series motor. Those motors are only
    limited in RPM's with respect to the load on them. I've seen those short
    a few turns of wire with out showing any ground shorts. You should take
    note the color of the magnetic wire if you can see it. It should not
    look like it has been subjected to heat! When this happens to these
    types of motors, you'll see more brush arcing than normal, even with
    a clean commutator and new brushes.

    Have a good day..

    Jamie
     
  12. Guest


    You are absolutely right. Zero ohms does indicate a short. But in
    the original post Andy said the motor did not run and the switch was
    good. So I assumed when he said Zero Ohms, he really meant the meter
    did not indicate anything and he really had a open. Not likely to be
    a dead short and not have a lot of excitement with 120 volts applied.
    Of course he may have a battery operated leaf blower................
    Or he has it plugged into a dead outlet.


    Dan
     
  13. P E Schoen

    P E Schoen Guest

    dcaster wrote in message
    He said in a later followup:

    That's why I suspected a bad winding or connection to a commutator section.

    The proper way to test this motor is with a "growler":
    http://en.wikipedia.org/wiki/Growler_(electrical_device)

    Here's a video of one being used on a 110V reel motor armaturer:



    Paul

    Paul
     
  14. P E Schoen

    P E Schoen Guest

    Some other educational videos, one on testing:



    and one on repair:



    Paul
     
  15. Andy K

    Andy K Guest

    It been interesting gentlemen.

    Looks like Toro doesn't want their products repairable by the consumer.

    Minimum order for a replacement motor is 500.(Mamco motor)

    I think the armature is shorted out.

    Andy
     
  16. Guest

    Check your Salvation Army store and the Goodwill. I bought a Sears
    leaf blower motor for $ 4. Did not include all the parts as nozzles
    and tubing.


    Dan
     
  17. Andy K

    Andy K Guest

    I fixed it.

    Those ridges in the brushes weren't normal.

    After sanding them smooth, the leaf blower is against producing 180 m.p.h. winds.

    I think the brushes are made of graphite.

    Andy
     
  18. josephkk

    josephkk Guest

    Republicans produce almost adequate amounts of hot air, but for really
    serious wind you need a Democrat. The only problem is that generate so
    much hot air that they are hard to control. All wild thrust and no wings
    to control them.

    ?-)
     
  19. Guest


    Impressive! I will have to keep this in mind.

    By the way, these kinds of AC motors also function nicely with about 24V DC. (Yes, DC.)

    Michael
     
  20. Jamie

    Jamie Guest

    Is it any wonder why they call them universal motors?


    Jamie
     
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