Adaptation of Carbon Brushes
2019-03-11 13:03:49

The concordance of the brushes and rings or collector surfaces is established by the adaptation of the brushes. There are many techniques used for this process:   

1. Carbon brushes are placed into the brush holder. A stripe grinder (80-100 grit) is placed between the brush and the collector and pulled tangentially forward and backward. After the working surface of the brush sits roughly on the collector or ring surface, it is adapted by pulling the grinder only in the rotation direction of teh machine in order to give the contact surface its final shape. The brush is elevated during pulling the stripe back and thus a free passage is allowed. Thus the main situation of the brushes when the machine is running is established and the brush adaptation process is completed.  

2. Tape grinder is wrapped arround the collector or the ring and fixed at its place with an adhesive tape. Than the brushes are placed into the holder. The rotor is rotated in the running direction of the machine. (applied at medium sized machines)   

3. The carbon brushes are fixed to their positions and the machine is run unloaded, preferably at a low rotation speed. A surface cleaning stone is held in front of each brush groups and thus both the collector is cleaned and the brushes are adapted by the sand powder which penetrates in the gap. This adaptation method is particularly suitable for large DC machines. (see Fig. 2) The adaptation process is completed when nearly 70% of the brush surface is adapted to the collector / ring surface. After the adaptation process need the carbon brushes to be dismantled and the machine needs to be cleaned by blowing oil-free pressurized air inside it.