Technical FAQs

My brushes are wearing out too fast. Would a harder brush work more effectively?

Hardness does not have a direct effect on brush life or brush wear. If the commutators are out of round or have high spots, a harder brush will actually have a tendency to bounce more and leave the commutator surface, potentially causing greater problems than before. Light loads, light spring force and poor commutator conditions are the usual causes of rapid brush wear.

My commutator is grooving. Would a softer brush be a solution?

Grooving occurs when there is poor electrical contact, resulting in a high resistance at the brush face with the ring or commutator. This may be due to roughness on the surface or vibration. Light loads, light spring force and poor commutator conditions are the usual causes of rapid brush wear.

Do you have a brush that does not dust?

No. Dusting occurs as the brushes carry current at levels below that required for the formation of a film on a commutator. The operation of brushes on a raw material surface has a very high coefficient of friction. Consequently, this results in a mechanical abrasion of carbon particles from the brush face or dusting. Some grades may dust less under different situations. Complete nameplate and operating information must be obtained for proper recommendations.

The brush writes like a #2 pencil. What grade is it?

This will make it difficult to determine the correct grade. Complete nameplate information should be included with the description of the brush.

Can you supply a brush like number xxxxx, except in grade xxxx?

Complete nameplate information should accompany this statement to determine if the new grade would actually improve the commutation or improve the existing problem.

Is this an exact cross to the OEM# xxxxx?

Unless HCPI manufactures the brushes for the OEM, our brushes will always be an equivalent to the OEM brush. No manufacturer can exactly duplicate another manufacturer due to varying quality standards, production capabilities and differences in raw materials.

The brush is wearing too fast. Should the spring force be decreased?

The first step would be to make measurement of the present spring force, calculate spring pressure, and compare value to recommended standards. In most situations it has been determined that the spring forces are inadequate. This results in poor brush contact, excess electrical wear, and a wide variety of maintenance problems.

An oversized motor was installed for reliability, potential future load increase, and long life. Why are the brushes wearing out rapidly?

When brushes operate at less than recommended current density, there will be inadequate low-friction film formation and increased mechanical wear. It would be best to submit nameplate data, operating current, brush size, and number of brushes per set to our technical staff for a recommendation on increasing current density or changing the brush grade.

ISO Certified Since 1994