how to test <12V DC motors, pully removal

Discussion in 'General Electronics Chat' started by electronis whiz, Jul 31, 2011.

  1. electronis whiz

    Thread Starter Well-Known Member

    Jul 29, 2010
    519
    27
    i have been going through some of my motors as a qhink i have mor than i need and ther may be some duds. i have been testing them just by listening for bearing noise. i have found a suprising amount that make noise when i hold them in a cerian position. most of them make a bad noise when upside down. is this normal if they were normaly ran horizontaly? or is this a sing of future problems with it? is there any other things i need to look for when testing them?
    any sugestions other than oil to fixe the ones that sound bad?
    witch type of motor do you use most often. i have a lot of old belt motors from old printers. there pretty good motors except for the odd pullys. they have no set screw so how can i get them off?
     
  2. someonesdad

    Senior Member

    Jul 7, 2009
    1,585
    141
    Depends on the type of bearings and the intended operation orientation -- but most bearings (journal, ball, or thrust) shouldn't be making noise. Noise means mechanical contact.

    The pulleys might be attached to the shaft with an adhesive (like Loctite) or just pressed on. Any tool seller can sell you bearing/pulley removal tools (lots of types to choose from).
     
  3. electronis whiz

    Thread Starter Well-Known Member

    Jul 29, 2010
    519
    27
    is there any way to tell just by looking at the motor case what type bearing it has?
    i have heared that jornal and sleve bearings are not that good. so i would kind of like to know what type of motors i have.
     
  4. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,766
    928
    I'd be very surprised if you found any ball bearings in any of them. The majority of micro fractional horsepower motors simply use bronze sleeve bearings. If they wear out to the point that you can move the shaft laterally then they are trashed. Movement in and out is common and does not indicate anything special as far as wear. sideways and vertical mounting is common, but pointing down with the pulley at the bottom is not normal and will probably cause noises when running. There are socket points at the opposite end which the shaft rides in, and placing them upside down lets them slip out of the socket and allows the rotor to contact the magnets on the insides of the can.
     
    electronis whiz likes this.
  5. electronis whiz

    Thread Starter Well-Known Member

    Jul 29, 2010
    519
    27
    ok i jusk thought of 1 more question. guite a few of my motors have a thin (aprox 1 mili meter thick) band around them. what is the porpous of this?
    prevent forin mater entrance, EMI emitance?
     
  6. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    It's extra steel (iron) to allow better magnetic coupling between the 2 permanent magnets inside. It gives stronger magnetism and more motor torque.
     
Loading...