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).
Instruction regarding the hardness of natural graphite grades for HM5 and HM6 type brushes.
| Identifier | ExFiles\Box 60\1\ Scan205 | |
| Date | 8th December 1924 | |
| RR 238 (150 BKS.) (DB{Donald Bastow - Suspensions} 461-8-12 24) MP 306975 ROLLS-ROYCE LTD. INSTRUCTIONS. To 19 Order No. PD 44 (2) Customer's No. the hardest of the natural graphite grades in the event of the HM{Capt. W. Hallam - Head Repairs}5 type showing excessive wear. Incidentally Link HM{Capt. W. Hallam - Head Repairs}6 brushes also represent the type which is said to be much used for automobile work. Signed C.A.P. This Sheet must be filed on completion of the work. | ||