From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Notes on testing procedures for commutators and brushes, including inspection criteria and load test methods.
| Identifier | ExFiles\Box 62\1\ scan0208 | |
| Date | 16th November 1933 guessed | |
| -3- NOTES RE TESTS 1, 2 & 3. (a) Before, between and after the light and load tests, the commutator and brushes should be carefully examined. The commutator should be found to be free from grease or varnish; this latter is difficult to detect when the motor is hot. The contact surface of the brushes should be examined after the light test to see that there is sufficient area of contact, which we consider should exceed 80% of the total. Running the light test on the motor considerably improves the bedding of the brushes for the load test. (b) Brushes should again be carefully inspected for freedom in the holders without excessive clearance. (c) A very good test for each brush consists in, on the load test, lifting off the companion brush opposite to itself, under which circumstances the brush under test has to carry the full current. If it does this without shewing signs of distress, which are indicated by jumping of the ammeter needle, it may be depended upon to be quite satisfactory when working in conjunction with its companion brush, provided this latter is equally good. Therefore, during the load test each brush in rotation should be lifted off the commutator and the effect observed on the ammeter and opposite brush. | ||