Never mix manufacturers grades, or different grades from one manufacturer on the same machine. Exception: Manufacturer recommends mixed brush assembly.
• Seat brush face to fit commutator with sand paper, followed by careful cleaning of commutator, brush and holder.
• Brush holder should not be set near the commutator, say about 2mm and should be in line with the commutator segments except on machines having circumferential staggered brush holders. The brush box must be in a clean and good condition.
• Check the brush clearance in the holder (average value 0,1mm).
• Check the position of trailing or reactive holder towards rotating position of commutator.
The brush staggering is very important. Arrange the lateral stagger of negative and positive brushes per successive
Spring pressure p KPa must be the same on all brushes in a set. Periodically each brush and holder should be checked. Average spring pressure value applied on industrial machines is about 180 g/cm2 (18p) of a brush cross section. Certain grades run even better at slightly higher pressures. On machines which are subject to heavy vibrations, pressure should be increased up to 50%.
The chart of common difficulties in relation with the patina prints should help to discover and eliminate damages occurring on commutators. If in doubt, please consult the machine- or brush manufacturer.