Bench Testing: Brushes

Replace brushes if wear exceed limit. Standard brush length is .650" (16.5 mm). Wear limit is .31" (8.0 mm). Measure brush spring pressure with brush tip protruding .08" (2.0 mm). Replace if pressure is less than 7.41 oz. (210 g) or if springs are corroded. New springs must have a pressure of 10.58-14.11 oz. (300-400 g).