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).
Summary table of bump test results for six different springs.
| Identifier | ExFiles\Box 52\2\ Scan190 | |
| Date | 30th August 1929 guessed | |
| SUMMARY OF LAST SIX SPRINGS ON BUMP TEST. No. | Make. | Wt. lbs. | Material. | Type. lbs. | Length. | Initial camber after test. | Loaded on lbs. | Position on bump. | Drg. No. | Total hrs. run. hs. {Lord Ernest Hives - Chair} ms. | REMARKS & BREAKAGES. 1 | Firths special. | 41 | Silico Manganese. | 1100 | 43¾" | 3 3/16 | | N.S. | | 13 45 | Top leaf 1½" from centre front end 2 | " | " | " | " | " | " | | O.S. | | 15 45 | Top leaf 8" from rear anchorage. 3 | Firths 'B' | " | " | " | " | 3½" | 1120 | N.S. | G.3159 DG.F.T.F &S. | 22 20 | Top leaf 9" from rear. 4 | " | " | " | " | " | 3 7/32" | 1109 | O.S. | G.3158 DG.F.T.F &S. | 40 35 | Top leaf 9" from rear. 7th. leaf from bottom. 5 | D. {John DeLooze - Company Secretary} type. | " | " | " | " | 3¾" | 1104 | O.S. | G.3172 DG.F.T.F &S. | 30 40 | After 24 hrs. 45 mins. 4th. leaf from top broke at first spring clip. At 30 hrs. 40 ms. top leaf broke 8" from R. {Sir Henry Royce} 6 | " | " | " | " | " | 3¼" | 1104 | N.S. | G.3171 DG.F.T.F &S. | | After 28 hrs. 30 mins 4th.leaf from top broke at first spring clip same as No. spring. This spg is still running. Run 55 hrs. so far. | ||