Pressure pad for double brushes - obviates lateral forces from collector spring produced by non-axial effects

摘要

The component brushes (11) of a double-brush can wear unevenly, become tilted or wedged in the brush holder through non-axial pressure from the collector spring. This is overcome by surmounting the brushes with a wedge-shaped piece (2) and a further piece (3) having a groove (6) in its upper face. The pressure element bears upon this groove. The slides of this further piece are part-cylindrical and the groove is of curved or V-shaped cross-section, suitably locating a roller-spring. Both additional pieces are of insulating or conducting material and need not be each of the same material. They are of low-friction material such as carbon. Both pieces may contain holes through which pass the current-carrying tails which thus approx. locate the pieces in the holder. This arrangement transmits the spring pressure axially and avoids lateral forces on the brushes.