Carson brush dc motor. (Machine-translation by Google Translate, not legally binding)
Carbon brush for current motor, especially for motor current switched mechanically, in which the current ripple, produced in switching current current motor, is discoverable with the help a electronic circuit and frequency ripple es evaluable as a measure of the speed, characterized in that the surface (1, 2; 21, 22; 31, 32; 41, 42) of the carbon brush (3 ; 23; 33; 43) is configured such that two support surfaces (4, 5) primarily defined point or line, found most spaced together as possible, are disposed between the carbon brush (3; 23; 33; 43) and the o contact blades (6, 7) collector (8) motor current. (Machine-translation by Google Translate, not legally binding)