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 the hardness and life of Woodhead and Firth spring leaves.
| Identifier | ExFiles\Box 72\3\ scan0136 | |
| Date | 12th July 1923 | |
| R.R. 403A (40 H) (SL 42 12-7-23). J.H., D.{John DeLooze - Company Secretary} -2- Expl. No. REF: Hsl/1620.9.24. EXPERIMENTAL REPORT. It will be seen that on the average the Woodhead has a lower brinnel. Comparison of hardness of top leaves. | Woodhead 12½% | Firth 25% | Firth 12½% | |------------------------|-------------------------|-------------------------| | Thickness of top leaf. | Brinnel. | Thickness of Top leaf. | Brinnel. | Thickness of Top leaf. | Brinnel. | | .282" | 375 | .292" | 375 | .308" | 388 | | .282" | 388 | .305" | 401 | .308" | 401 | | .286" | 388 | .307" | 401 | .308" | 401 | | .292" | 363 | .308" | 401 | | | | .293" | 388 | .308" | 401 | | | | .300" | 363 | .310" | 415 | | | Aver: life. hrs.mins. 21 29 hrs. mins. 16 17 hrs. mins. 15 45 N.B. The figure given for the thickness of the top top leaves are averages, as the actual thickness varies within about .010" from point to point. We attach a chemical analysis of the top plate from 6 of the latest Woodhead springs. We also attach a comparison of the life of front springs classified under different poundages. It will be seen that stiffer springs give longer life. These springs are all Firths 25% stiffer. Hs.{Lord Ernest Hives - Chair} | ||