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).
Comparing standard and Firths special front springs, type 650 lbs.
| Identifier | ExFiles\Box 119\2\ scan0243 | |
| Date | 1st March 1925 | |
| R.R. 493A (50m) (D.B. 175 25-9-24) J.H.D. EXPERIMENTAL REPORT. -2- Expl. No. REF Hs{Lord Ernest Hives - Chair}/RB{R. Bowen}/LG23. 3. 25. NOTES. COMPARISON OF STANDARD AND FIRTHS SPECIAL SPRINGS. TYPE 650 LBS. FRONT. ITEM. | STANDARD. | SPECIAL. Drawing. | F.53163 Piece No. | F.53167 No. of leaves. | 11 | 11 Thickness of leaf (top) | .250 (to drg.) .236 (actual) | .236 (average of 5) Loaded camber. | .150" | .150" Length. | 36" | 36" Camber of top leaf unloaded. | 1.600" max. | 2.220" Average life on bump test. | 14 1/2 hrs. | 14 1/2 hrs. From the above tests we see no reason to believe that these springs will give any longer life on the road than the ordinary standard type. The only difference between the two types lies in the initial camber of the top leaf in its free state. contd :- | ||