It should not exceed 0.03 mm in one revolution. The value is measured using a profile meter.

This measurement allows to study the deformation on commutator or slip rings. We can also measure the depth of wear on brush tracks to determine what type of tool is best adapted to the rectification.

We must avoid peaks (Ra) less than 0.2 µmm because it creates mechanical instability and can cause vibration. A low roughness reduces the number of points of contact between the carbon brush and the commutator or slip rings. We use a roughness meter to measure the surface roughness.

We use a probe between the pressure system and the carbon brush to measure the spring pressure. This is essential to detect any deviation from our recommended pressure.

Incorrect alignment of the neutral will lead bad operation and cause sparking.