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).
Brinell hardness test results for chassis spring leaves, noting failures and hours run.
| Identifier | ExFiles\Box 119\2\ scan0114 | |
| Date | 28th June 1920 guessed | |
| CHASSIS SPRINGS. BRINELL TESTS - CONTD. Spring 363.Z. C2. 2216 lbs. Leaves. | Brin: | Remarks. | Hrs. run. 1 | 388 | Cracked. | 2 | 388 | Broken. | 3 | 415/388 | " | 9 hrs. 15 hrs. 4 | 401 | O.K. | 5 | 352 | O.K. | 6 | 388 | O.K. | | ||