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).
Cost and properties of 'Hykro' crankshaft material compared to V.C.M.
| Identifier | ExFiles\Box 142\4\ scan0183 | |
| Date | 18th November 1936 | |
| c.Rm.{William Robotham - Chief Engineer} O.E. 1203 BY.2/G.18.11.36. CRANKSHAFT MATERIAL. -------------------- I understand that you were informed that 'Hykro' was a very costly material compared with V.C.M. In order to settle the matter I telephoned through to Mr. Burton of the English Steel Corporation, who are the originators of this type of material, and he informed me at the end of the day, after making a thorough investigation, that there would be a 5% increase in cost. This was due to the fact that they could not use ordinary scrap, this material having to be kept completely free of nickel, and therefore they were compelled to use a larger proportion of virgin materials and it was this particular factor that caused the increase of 5%, otherwise there would not have been any change. I would like to point out that the use of case hardening material for the crankshaft involves a considerable amount of stretching. Incidentally, Mr. Burton reminded me of this himself, although I was well aware of the point before and remarked that the Leyland people had a very large amount of stretching to do to make the cranks reasonable. Furthermore, the stretching of a case hardened material unless the webs etc. are left soft results in a good bit of the distortion being reproduced in the crank after it has been running for some time in service, owing to the fact that any stretching which is done only affects a comparatively small layer of fibres on the surface of the material being stretched, the inner fibres re-acting against the force in question and tending to reproduce the original distortion. BY.{R.W. Bailey - Chief Engineer} | ||