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).
The wear measurements of brushes, comparing results to a previous machine test.
| Identifier | ExFiles\Box 60\1\ Scan027 | |
| Date | 29th June 1920 | |
| RR 238 (15Q BKS.) (SH57. 29-6-20.) MP 224358 ROLLS-ROYCE LTD. INSTRUCTIONS. 19 To Order No. PC 143 (2) Customer's No. The amount of wear of the brushes was as follows:- | | Positive | Negative | Control | |-------|----------|----------|---------| | Inner | .0025" | .003" | .003" | | Outer | .002" | .002" | .0035" | These results are not as good as those of the NB machine, the wear of the brushes, and the blackening of the commutator and brush surfaces being definitely worse. Signed C.A.P. This Sheet must be filed on completion of the work. | ||