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 log for rear bumper springs detailing failures over time and subsequent hardness testing.
| Identifier | ExFiles\Box 119\2\ scan0117 | |
| Date | 24th July 1920 | |
| X133 (crossed out) REAR BUMPER TEST. X.3981 96/F.C. HANDWRITTEN: File STAMP: RECEIVED 24.JUL.20 Springs F.4666 - 2324 lbs. O.S. " F.4665 - 2226 lbs. N.S. Date. | Total hrs. run. | Remarks. 19.7.20 | 1 hr. 10 mins. | Front tie clip O.S. spring broken. 20.7.20 | | O.K. 21.7.20 | 19 hrs. 45 mins. | Rear tie clip O.S. spring broken. 22.7.20 | 21 hrs. 15 mins. | K.419 Bolt broken on centre main spring bracket. 22.7.20 | 24 hrs. 15 mins. | O.S. Spring 5th. leaf broken (centre) 23.7.20 | 61 hrs. 45 mins. | N.S. spring 2nd., 8th., 9th., and 10th. leaves broken centre. 24.7.20 | 28 hrs. 20 mins. | O.S. Spring 6th. and 7th. leaves broken (centre) 26.7.20 | 29 hrs. 5 mins. | O.S. Spring 8th. leaf broken (centre) F.4666 (2324 lbs) Spring F.4665 (2226 lbs.) run 61 hrs. 45 mins. Leaves. | Brinell. | Remarks. 1 | 444 | O.K. 2 | 444 & 415 | broken centre 3 | 401 | O.K. 4 | 444 | O.K. 5 | 415 | O.K. 6 | 415 | O.K. 7 | 415 | O.K. 8 | 429 | broken centre 9 | 429 & 444 | broken centre 10 | 429 & 363 | broken centre 11 | 415 | O.K. | ||