The Xi'an Sima Motor original carbon brush holder (brush holder) features a sturdy structure that ensures long-lasting stability of the brush, making it easy to install and remove the brush within the brush box when inspecting or replacing the brush. It allows for adjustment of the exposed part of the brush in the brush box (the gap between the lower edge of the brush box and the commutator or collector ring surface) to prevent wear on the commutator or collector ring. Additionally, the carbon brush holder minimizes the impact of changes in brush pressure, the direction of pressure, and the position of pressure on brush wear.

The role of the carbon brush holder (brush holder) is to apply pressure to the brush, which makes sliding contact with the surface of the commutator or collector ring, ensuring stable current conduction between the stationary and rotating parts of the motor. The carbon brush holder (brush holder) and carbon brushes are critical components for the motor. Regardless of the brush's performance, if the holder is unsuitable, the carbon brush cannot perform to its optimal characteristics and may significantly affect the motor’s performance and lifespan.

The material and technical specifications of the Xi'an Sima Motor original carbon brush holder (brush holder) meet the design requirements outlined in the drawing. The regular design tolerances of the brush box hole are generally based on the base hole system for interference fits: radial tolerance H7, axial tolerance H11. The roughness of the brush box hole after reaming or pushing is controlled at Ra3.2-Ra1.6, and special requirements can include adding an extrusion block to reduce roughness to Ra0.8. For multi-hole brush boxes, multiple reamers or push tools are used simultaneously to ensure coaxiality after machining. The non-concentricity tolerance of multi-hole brush boxes is no greater than 0.36mm. The parallelism and spacing tolerance of the fixed surface of the brush holder and the centerline of the brush box is A = ±0.2. The bottom surface of the brush box hole is perpendicular to the brush box wall and to the fixed surface, with perpendicularity no greater than 0.25mm. The brush holder’s pressure finger rotates smoothly, and when lifted, it should fall freely without dead points or jamming. The joints are riveted firmly with no risk of detachment. The surface can be treated with methods such as Ni-plating, Zn-plating, Cr-plating, gold imitation plating, copper plating, chemical oxidation, and acid washing, depending on the usage environment, to ensure the long service life of the carbon brush holder (brush holder). Sharp edges, burrs, or other defects on the brush box body should be avoided, as such defects can cause discharge phenomena in humid environments. The pressure of the newly manufactured brush box is already adjusted. However, as usage time increases, the spring's elasticity will fatigue and diminish. When the loss becomes too great, sparks may occur at the bottom of the carbon brush. The pressure should be adjusted as follows: for metallurgical, power generation, and crane motor brushes, the pressure should be between 0.15–0.35Kg/mm²; for traction motor brushes, the pressure should be between 0.3–0.4Kg/mm². The pressure deviation of the carbon brush holder (brush holder) on the same motor should not exceed 10%; otherwise, it will result in uneven current density and local overload.

Overview of the Motor Carbon Brush Holder

The role of the carbon brush holder is to apply pressure through a spring on the carbon brush, which slides in contact with the surface of the commutator or collector ring, ensuring stable current conduction between the stationary and rotating parts of the motor. The carbon brush holder and carbon brush are both critical components for the motor. Regardless of the characteristics of the brush, if the brush holder is not suitable, the carbon brush cannot fully exhibit its excellent characteristics, and this will significantly affect the motor's performance and lifespan.

The structure of the carbon brush holder consists of the brush box part that keeps the brush in the specified position, the pressure part that applies appropriate pressure to prevent brush vibration, the frame part that connects the brush box and the pressure part, and the fixed part that secures the brush holder to the motor.

Performance Requirements of the Carbon Brush Holder

The carbon brush holder must stabilize the carbon brush, making it easy to install and remove the brush when inspecting or replacing the brush in the brush box. It must also allow for adjustment of the exposed part of the brush in the brush box (the gap between the lower edge of the brush box and the commutator or collector ring surface) to prevent wear on the commutator or collector ring. The impact of changes in brush pressure, pressure direction, and pressure position on brush wear must be minimized, and the structure must be sturdy. The carbon brush holder is mainly made of bronze castings, aluminum castings, and other composite materials. The materials used must have excellent mechanical strength, machinability, corrosion resistance, heat dissipation properties, and electrical conductivity, among other qualities.