Product Name
Carbon Brush
Alternative Name
Motor Brush
Product Image
Product Application
Carbon brush is a device used in electric motors, generators, or other rotating machinery to realize the transmission of energy or signals between fixed parts and rotating parts. It applies external current (excitation current) to the rotating rotor through the carbon brush, and can also conduct static charges on the main shaft to the ground via the carbon brush. Additionally, it can lead the main shaft (ground) to the protection device for rotor grounding protection and measurement of the positive and negative voltage of the rotor to the ground. In commutator motors, the brush also plays a role in commutation.
Product Material
Carbon product with copper wire.
Product Features
- Excellent Commutation and Current Collection Performance: It can suppress sparks within the allowable range, with low energy loss.
- Long Service Life: It causes little wear to the commutator, which can reduce the replacement frequency.
- Stable Operation: No overheating during operation, low noise, reliable assembly, and no damage.
Technical Parameters
Technical parameters of carbon brushes vary by model, generally including resistivity, Rockwell hardness, bulk density, current density, contact voltage drop, friction coefficient, 50-hour wear, allowable circumferential speed, unit pressure, etc.
Installation Method
- Requirement for Carbon Brush Consistency: It is forbidden to install carbon brushes of different brands and materials in the same motor.
- Inspection of Springs and Bolts: Ensure that the springs are pressed well with uniform spring pressure, the copper wire fixing bolts are firm, and the fixing method does not hinder the use of carbon brushes.
- Cleanliness Requirement: No oil stains or grease are allowed to adhere to the carbon brushes and the friction surfaces of rotating parts.
- Carbon Brush Running-In: Natural running-in, manual running-in, or tool running-in can be adopted to ensure full contact between the friction surface of the carbon brush and that of the rotating part.
Usage Precautions
- Gap Between Carbon Brush and Brush Holder: When the carbon brush is installed in the brush holder, it must be able to move up and down freely. The gap between the carbon brush and the inner wall of the brush holder should be approximately 0.1 mm.
- Distance Between Brush Holder and Commutator: The distance from the lower edge of the brush holder to the surface of the commutator should be maintained at approximately 2 mm.
- Replacement of Carbon Brushes: When the carbon brushes are worn to a certain extent, they should all be replaced; otherwise, uneven current distribution may occur.
- Pressure of Carbon Brushes: The pressure applied to each carbon brush of the same motor should be as uniform as possible to prevent overheating and sparking of individual carbon brushes.
Maintenance
- Regular Inspection of Wear Amount: When the remaining thickness of the carbon brush is one-third of the original, it should be replaced in a timely manner.
- Cleaning of Carbon Deposits: Wipe the contact surface of the carbon brush with a brush dipped in alcohol. Avoid using sandpaper for grinding to prevent damage to the surface conductive layer.
- Adjustment of Spring Pressure: Use a dynamometer to adjust the spring pressure to the value specified by the equipment to ensure good contact between the carbon brush and the slip ring.
Common Problems and Solutions
- Excessive Sparking: This may be caused by loose springs or uneven contact surfaces. The spring pressure can be adjusted or the contact surfaces can be ground.
- Abnormal Noise: It is often caused by loose carbon brushes; simply re-fix the carbon brushes.
- Excessive Heating: Check whether the current exceeds the standard or the ventilation is poor.
- Excessive Wear: This may be due to mismatched materials; replace with a suitable carbon brush model.
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