Common faults and repair methods of brushed motors

Common problems with brushed motors are common failures of carbon brushes and commutators. Apart from that, there are also non-running, abnormalities in operation, too fast, too slow, strange noises, sparks, etc. Damage to the carbon brushes of a brushed motor can cause the motor to terminate and the brushes should be replaced. Commutator common failure will cause motor termination, more serious transmission gear speed motor termination, must replace the commutator.

1. Carbon brush maintenance.

Before overhauling the carbon brushes, distinguish whether the carbon brushes are not destroyed, depending on whether the carbon brushes are replaced within a year, or gently tap the motor with a wooden stick. If the motor drive gear speed motor rotation termination, indicating that the carbon brush has a common failure, must be maintained. The motor bearing end cover can be opened with a tensioner, check the level of carbon brush damage, and the carbon brush holder is not destroyed, followed by the replacement of new carbon brushes and carbon brush holder. Before replacing the carbon brushes, remove the old carbon brushes first, and then put 2 new carbon brushes into the brush, welded with chrome iron welding, put it into the suitable part, and torque it with screws. Eventually, the brushes were immobilized on the motor motor stator.

Sparks because the carbon brushes and commutator have poor contact phenomenon, due to the commutator or carbon brush damage or torsion spring working pressure is not enough, the contact area as if it does not joint, resulting in carbon brush chatter.

Overhaul solution:

①If the transmission gear speed motor carbon brushes and commutator poor contact phenomenon, each carbon brush contact area should be more than 75%.

② Check whether the brush is loose, and adjust the tightening.

③ If the carbon brushes and brush grips with each other unreasonable, should be adjusted to make it easy to roll, the total width of the gap is 0.06 ~ 0.3mm, the length of the gap is 0.07 ~ 0.35mm.

④ The working pressure of carbon brushes is not the same, the regulation is 1.5~2.5kPa, but the working pressure of each carbon brush must be proportional, and the deviation should not be more than 20%.

⑤ If the carbon brushes are not proportional all over, equal area correction should be carried out.

⑥ If the carbon brushes are not of the same type and specification, the carbon brushes should be changed according to the original shape.

⑦ If the carbon brushes deviate from the neutral point, calibration and adjustment should be carried out.

⑧Synchronous motor winding resistance short-circuit fault mild, electric welding welding common faults.

⑨ Improve the touch of carbon brushes and commutator, leveling the contact area of carbon brushes.

⑩ Replacement of carbon brushes or torsion springs.

2. Commutator maintenance.

Check the level of damage to the commutator. If the surface metal sheet is uneven or short-circuited, replace the commutator with a new one. Weld all the connections between the electromagnetic coil and the middle of the commutator with a soldering iron, gently open the copper core wire around the commutator with both hands and remove the commutator. Place a commutator of the same size into the initial part of the commutator and solder the beginning of the solenoid coil and the commutator with a soldering iron. Subsequently, repair the copper core wire.

If the electromagnetic coil or commutator short circuit fault is more serious, the short circuit and carbon brush chatter is more serious, sometimes the amount of current is too large, it is likely to cause the spark to continue, too many consecutively, and finally become a ring fire.

Inspection and repair solution:

① Transmission gear speed motor commutator surface with oil stains, wipe with alcohol.

② Commutator shaft force, and deformation, should replace the commutator.

③ Synchronous motor winding resistance short circuit fault problem is more serious.

④ Commutator mica protruding, should carry out engraved groove, chamfering, grinding.

⑤ Synchronous motor winding resistance and the commutator are more serious open welding.

⑥ Look for short-circuit faults or interruption points and remove common faults.