DC Motor

To be checked: -Carbon brushes and brush holders
-Brush pressure
-Commutator brush mobility in the holder
Maintenance Interval: Every 600 operating hours
Tolerance: must not wear down below the mark


ATTENTION : Always disconnect the machine from the mains !
Replacement carbon brushes are usually adapted to the radius of the commutator on the contact surface. If this is not the case, you must sand the brushes to size using fine sandpaper. Place the sandpaper between the brushes and the commutator and turn the sandpaper evenly in the impeller`s direction of rotation (IMPORTANT: rough side of the sandpaper must be towards the carbon brushes- see figure below).

Then carefully remove as much of the grit and fine particles as possible from the brush rocker and the commutator.Twisting the brushgear
To change the carbon brushes, release the locking screws from the operator opening on the terminal box side, loosen and twist the brushgear. After that turn the brushgear back to its original position with the marks on the end shield and the brushgear lines up exactly with one another.

Keep the commutator free of dust and oil: Wipe off the oil with a dry rag and blow off any loose dust. Remove every damage such as burn stains, beads of molten metal, rough areas and slight grooving, using progessively finer grades of sandpaper. Make sure that you do not sand the commutator out-of round. Always blow out the grit. The patina (the discolouration ranging from light to dark brown of the brush paths) shows that the equipment is operating properly and should never be removed. Out-of-round running surfaces, protruding segments, pitting and grooving can only be corrected by skimming.

Brush-holder postion
Adjust the holder to a distance of about 1.5 mm to the commutator surface when the commutator has been outside diameter-turned.

EXTEND the Life-Time of carbon brushes by:

  • Balance the wheels of the rotor
  • Adjust/Carry out ventilation to get an optimal temperature of the ventilator
  • Check V-belts tension and do not combine new and used V-belts
  • Vibration-free adjustment of the motor
  • Regular change of air filter
  • Clean environment of the rotor and brushes (no oil spray)