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).
Test results for narrow brushes on a K machine, comparing wear against standard brushes.
| Identifier | ExFiles\Box 60\1\ Scan009 | |
| Date | 13th October 1926 | |
| RR 238.(150 BKS.) (SH57.29-6-20.) MP 224358 ROLLS-ROYCE LTD. INSTRUCTIONS. To: EFC Order No.: PC117 Customer's No.: X 8673 Test of Narrow Brushes on K Machine. A set of narrow brushes of standard grade (Z) material, have been tested under the same conditions, as near as possible, as the set of standard brushes on AV machine, reported in PC 109/30-8-26 The general appearance of the surfaces of the commutator and brushes is certainly no worse than in the case of the standard brushes; if anything being a little better, especially the control brush surfaces. The wear of the brushes is as follows:- | | Positive | Negative | Control | |---|---|---|---| | Inner | .002" | .002" | .003" | | Outer | .003" | .002" | .004" | This is less than that for the standard brushes, and particularly so in the case of cont'd.{John DeLooze - Company Secretary} Signed This Sheet must be filed on completion of the work. | ||