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).
Bumper test report on an 11-leaf spring, showing Brinell hardness and failures.
| Identifier | ExFiles\Box 80\2\ scan0248 | |
| Date | 5th November 1920 | |
| LAS X2628 BUMPER TEST. F.4630 - Spring consisting of 11 leaves, with tapered ends, nibs, slots and tie clips. Lbs. 950. Fitted to N.S. Bump chassis 5.11.20. No. of leaves. Brinell. Remarks. Time run. 1 415 O.K. 2 444 O.K. 3 415 O.K. 4 477 Broken in centre. 5 444 O.K. 15 hrs. 35 mins. 6 161 O.K. 7 444 O.K. 8 415 O.K. 9 429 O.K. 10 477 Broken in centre. 11 388 " " " | ||