Spring Pressure
Appropriate spring pressure is essential in achieving optimum brush performance. Each grade classification has its own particular pressure range in which it operates best. A small spring tension scale(Figure E), is used to measure spring pressure. A leather loop, which is more accurate than the conventional hook or ring, is placed under the end of the spring finger where the finger touches the brush. To measure the pressure, place a strip of paper between the brush and the commutator and pull outward on the ring. When the paper slips freely, the scale indicates the spring pressure. For your convenience, the recommended spring pressures are listed below.
RECOMMENDED SPRING PRESSURES
| Carbon brushes | 1 3/4 to 2 1/2 lbs. per sq.In. |
| Carbon-graphite brushes (soft) | 1 1/4 to 2 lbs. per sq.In. |
| Carbon-graphite brushes (hard) | 3 to 4 lbs. per sq.In. |
| Electro-graphite brushes | 2 1/4 to 4 lbs. per sq.In. |
| Metal-graphite brushes | 2 1/2 to 5 lbs. per sq.In. |
Caution: Make certain that switch is disengaged before adjusting! Prev Next