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).
The unmachinability of 4-carbon crankshafts due to high Brinell hardness and the required tempering treatment.
| Identifier | ExFiles\Box 132\2\ scan0163 | |
| Date | 30th March 1940 | |
| 1116 Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation} Rm.{William Robotham - Chief Engineer}6/MML.30.3.40. Olley says that the 4-carbon crank-shafts with a Brinell of 320 are unmachineable. By.{R.W. Bailey - Chief Engineer} has insisted that all the 4-carbon cranks that we have fitted to our engines should be tempered until they are above this figure. We should like all the new cranks coming through to be left in a state where they are perfectly easy to machine. Will you please go into the matter with Marriott and make sure that the forgings do not receive this tempering treatment before they reach the Works. I believe I am correct in assuming that a good deal of machining has to be done after the shafts have been brought up to this high Brinell. Rm.{William Robotham - Chief Engineer} | ||