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).
Suggested five-step process for manufacturing hardened crankshafts.
| Identifier | ExFiles\Box 93\5\ scan0146 | |
| Date | 25th November 1937 | |
| CRANKSHAFTS. In connection with the suggestion that we try out a .4/.5 carbon steel for our crankshafts, working at a brinell round about 400, the method which I had in mind for handling the crankshaft to overcome the obvious difficulty of forging, which has been hardened to this figure, is as follows :- /machining a (a). Machine the shaft all over, finishing the webs and leaving .075 on the diameter of the pins and journals. This work would be done before heat treating the shaft. (b). Produce a light nickel deposit all over the crankshaft, the thickness of which need not be more than .00025 to .0005, the object of this being to ensure the shaft hardening out regularly during the quench. Mr. Talbot has shown in connection with the .5/.6 carbon steel liners for aero cylinder that the oxide created when attempting to heat treat these without nickel plating gave variations in brinell after the first quench of between 341 and 577. By the use of a light coating of nickel before heat treating the hardness after quenching was consistent all over the forging, being in the neighbourhood of 577. (c). Heat treat in the usual way, making sure, however, that in quenching, the shaft is lowered down into the oil with the axis in a horizontal plane. (d). Finish by grinding on the pins & journals in the usual way. (e). If screwed threads are required, these would probably have to be produced before hardening. It is suggested that we try out a Bentley 50 crank, made in .4/.5 carbon steel as a first attempt. This will obviously limit the difficulties, and enable us to get a line on the practicability of the idea, with a much reduced expenditure. BY.{R.W. Bailey - Chief Engineer} | ||