A commutation performance and wear of carbon-fiber brush in gasoline

It is well known that many small dc motors are used in automotive electrical equipments. Among them, a dc motor for a fuel pump has a distinctive feature that its brush and commutator work in gasoline. In our previous reports it has been made clear that the wear of metal-graphite and carbon brushes is much larger in gasoline than in air, and severe wear was sometimes observed. In this paper a carbon-fiber brush is tested in wear and sliding performance in gasoline and compared with a carbon brush. Consequently it can be found that the carbon-fiber brush is better than the carbon brush in commutation ability and wear in gasoline. When a severe wear was observed, a carbon film fully covered a commutator surface under both carbon-fiber and carbon brushes.