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).
Report comparing the wear and noise of control brushes against standard brushes, attributing lower wear to cooler running conditions.
| Identifier | ExFiles\Box 60\1\ Scan010 | |
| Date | 29th June 1920 | |
| RR 238 (150.BKS.) (SH57.29-6-20.) MP 224358 ROLLS-ROYCE LTD. INSTRUCTIONS. To_____________________ 19 Order No. PC 117 (2) Customer's No._____________ the control brushes where the wear is .003" to .004" as compared with .018" to .020" of the standard brushes. The smaller amount of brush wear is thought to be due to the cooler running of the commutator and brushes of the NB machine, as it has been observed on previous occasions that as the machines get hot, the brushes become very hot, and appear to become dry and to wear more rapidly, depositing on the commutator a very fine dust. These conditions appear to be the cause of the shrieking noise given off at times more or less by all grades of brushes with the exception of the LFC 3AB8. It cannot however be said that, on this test, the narrow brushes were any quieter than the standard, in spite of the cooler running and less wear. Signed C.A.P. This Sheet must be filed on completion of the work. | ||