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).
Failures and experiences with Swedish carbon steel wire in car and aero engine components.
| Identifier | ExFiles\Box 158\5\ scan0058 | |
| Date | 30th January 1940 | |
| - 2 - Continued:- been through several, and this fact is concurred in by the customer - the Air Ministry. What are the facts in regard to our experience in Swedish carbon steel wire:- We have, all told, 700 chassis so fitted, made up of 67 Rolls-Royce 25/30 HP., 40 Bentley "M" Series, and 600 Wraiths. Failures are as follows:- 5 failures on 25/30 HP. 2 failures on Bentley "M" Series. 5 failures on Wraith. It must be remembered also that none of these cars has done any real mileage as, with the exception of the 67 Rolls-Royce 25/30 HP., the 700 chassis have all been manufactured during the year October 1938 to October 1939; bodies have had to be fitted and therefore the actual running time has been strictly limited. Personally, I do not mind which type of wire or form of spring is finally successful, but I am certain that Swedish wire, as we have so far used it, will be inadequate for the duty on our current aero engines, as the design of the valve gear is such as to put up the stress in the springs beyond the capacity of the wire in question, unless it can be shown that severe and accurately controlled cold working by steel shot impact from a wheelabrator gives a marked increase in capacity. I have given Oy., carte blanche as to what steel he uses for the wire, the method of finishing, and even the design of the spring if it will fit into the space provided, if he, in turn, will prove his results on a rig, using the cam form I have outlined, for a period of two hundred hours. In fairness, it must at least be conceded that I produced reliable wire when no one else knew how to do it, and if this is the case, my estimate of what is required and the difficulty of attainment which are based on a similar insight of the present problem, should not be lightly discounted. BY.{R.W. Bailey - Chief Engineer} | ||