1. In order to ensure the normal operation of the motor, it is very important to select the brush type accurately. Due to the different raw materials and technologies used in the production of brushes, their technical functions are also different. Therefore, when choosing a brush, we should think about the function of the brush and the request of the motor to the brush. The symbol of the outstanding function of the brush should be:

A in the commutator or collector ring surface can quickly form a layer of uniform, moderate and stable oxide film.

B brush has a long service life and does not wear the commutator or collector ring

The c brush has excellent commutation and current collection functions, so that the spark is suppressed within the allowable range and the energy loss is small.

d When the brush is working, it is not hot, the noise is small, the equipment is reliable and not damaged.

2. The brush shall be installed in the brush holder to ensure that it can move up and down leisurely. The space between the brush and the inner wall of the brush holder is between 0.1 and 0.3mm, so as to prevent the brush and the brush holder from shaking greatly due to the space. The spacing of the lower edge of the brush holder from the commutator surface should be maintained at about 2mm. If the interval is too small, the brush holder will touch the commutator briefly. If the interval is too large, the brush will tremble easily and cause damage.

3. On the same motor, in principle, the same type of brush should be used, but for a single large and medium-sized motor with extremely difficult commutation, a twin brush can be used. The sliding side uses good lubrication function, and the sliding side uses a brush with strong spark suppression ability, so that the work of the brush can be improved.

4. If the brush is worn to a certain extent, it is necessary to replace the new brush. It is best to replace the brush at one time. Assuming that the old and the new are mixed, uneven current distribution may occur. For large units, stopping and replacing brushes will definitely affect the production, and we can choose not to stop. We usually recommend that customers replace 20% of the brushes (I .e. 20% of each brush rod of each motor) at an interval of 1-2 weeks, and gradually replace other brushes after running-in to ensure the normal and continuous operation of the unit.

5. In order to make excellent contact between the brush and the commutator, the new brush should be ground radian, which is usually carried out on the motor. Place a piece of fine glass sandpaper between the brush and the commutator. Under normal spring pressure, grind the brush along the rotation direction of the motor. The sandpaper should stick the commutator as tightly as possible until the arc surface of the brush fits. Then remove the sandpaper, blow the dust with compressed air, and wipe it clean with a soft cloth. Abrasive brush should not use emery paper to prevent emery particles embedded in the commutator slot, in the motor work, scratch the brush and commutator surface. After the arc is ground, the motor works at a load of 20-30% for several hours to make the brush and commutator run-in and establish a uniform oxide film. Then gradually trek the current to the rated load.

6. The unit pressure applied to each brush of the same motor should be uniform to avoid uneven current distribution, resulting in overheating and sparks of a single brush. The unit pressure of the brush should be selected according to the "brush technology function table". For motors with higher speed or motors working under oscillating conditions, the unit pressure should be properly trekked to ensure normal operation. For example, the unit brush pressure of the traction motor is 0.4-0.6kgf/cm2.

Usually, the unit pressure of the brush is too high, the wear of the brush is aggravated, the unit pressure is too small, the contact is not stable, and the mechanical spark appears briefly.

Elements of spark onset of brush and method of cleaning

Resulting element processing method

a Poor adjustment of the additional pole ---------- use shunt or adjust the air gap of the additional pole, or change the brush type.

B Excellent mica-engraving mica or using abrasive brushes

c Disconnection of commutator adding piece connection ------ welding from scratch

d Inaccurate brush orientation-adjust the brush holder to accurate orientation

e brush holder spacing or uneven placement ------- correct brush holder spacing and placement

F commutator or collector ring is painful-it is best to turn or grind from scratch at rated speed.

G commutator is loose, commutator segments are concave and convex-tighten, turn or grind from scratch

h commutator segment has oil stain ------------ clean commutator segment and sealed bearing

I the brush adheres or stays in the brush holder-check whether the brush standard is accurate, clean the brush and brush holder to remove any burrs.

J brush running-in poor --------- running-in brush