I. Basic Information and Compatible Models

• Product Positioning

• This carbon brush is a dedicated wear-and-tear part for breakers (Bohrhammer), suitable for models RH 1500 and BT 1500, as well as compatible models from brands like Bosch or Metabo.

• Core Function

• Transmits current to the rotor windings through sliding contact with the motor commutator, driving the breaker to achieve combined rotation and impact functions.

II. Technical Parameters and Key Features

1. Material and Performance

• Made of electrographite composite with 18–22% copper content, ensuring high electrical conductivity (resistivity ≤12×10⁻⁶Ω·m) and wear resistance (wear rate <0.18mm/100h).

• The spring is made of stainless steel (SUS301) with fatigue strength up to 10⁶ cycles, maintaining constant pressure (1.8–2.2kg) under high-frequency impacts.

2. Dimension Specifications

• Typical dimensions: 5×12×20mm (thickness×width×length), subject to actual measurement of old parts. A tolerance of ±0.5mm may exist for some models.

III. Working Mechanism and Wear Characteristics

• Current Conduction Process

1. Current flows from power source → carbon brush → commutator → rotor windings → forms a rotating magnetic field → drives piston reciprocation.

• Wear Warning Signs

• Replace when the remaining carbon brush length <8mm;

• Abnormal sparking (＞3mm length), rotational speed fluctuations, or startup delays in the motor.

IV. Installation and Maintenance Guidelines

1. Replacement Steps

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   ① Power off and remove the breaker side cover;  
   ② Take out the old carbon brush assembly (note the spring latch direction);  
   ③ Clean carbon powder in the commutator grooves with compressed air;  
   ④ The new carbon brush arc must match the commutator curvature (shape with sandpaper if needed);  
   ⑤ Test spring pressure after installation (recommend using a spring tension gauge).

   
   

2. Maintenance Cycle

• Inspect carbon brush wear every 50 hours of use;

• Clean the commutator and apply a thin layer of conductive paste (e.g., MG Chemicals 846) every 100 hours.

V. Comparison with Other Tool Carbon Brushes

VI. Purchase Notes and Precautions

1. Specification Verification

• Measure the actual dimensions of the old carbon brush (precise to 0.1mm);

• Confirm the spring free length (typically 25–30mm) and preload (approx. 10mm).

2. Compatibility Tips

• Some European-brand breakers (e.g., Metabo) use offset carbon brush designs; pay attention to the installation direction;

• If abnormalities persist after replacement, check if the commutator mica flakes are protruding (standard: 0.2–0.3mm below copper flakes).