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).
Clarifying the facts regarding the testing and performance of different types and materials of valve springs.
| Identifier | ExFiles\Box 158\4\ scan0129 | |
| Date | 4th May 1937 | |
| Hives 1360. BY.2/G.4.5.37. c. Rm.{William Robotham - Chief Engineer} Please see me VALVE SPRINGS. It occurred to me at the Conference on Tuesday last that the actual facts of the case in regard to the chrome vanadium wire as against any other type are not clearly understood, mainly because the facts are not being clearly stated in reports. There are two main factors which must be kept clearly in mind if the real value of one wire against the other is to be appreciated viz :- (a). There are two forms of springs being tested (1) The original type of spring, tapered with } This type proportionate clearances between the coils. } surges. (2) The American form of spring in which the } This type coils at the stationary end of the spring } is free are so closely coiled as to come into } from solid contact before the valve is fully open. } surging (b). The types of wire which are being used are:- (1) Chrome Vanadium. (2) Hard drawn carbon steel. (3) Carbon steel, heat treated and tempered in the coil. The point I wish to make is that in all the reports which have been made the heat treated and tempered wire, which is giving good results as it is being used is being in every case tested in a modified form of spring which is admittedly better owing to the fact that it damps out the surging or periodic effects. Whenever chrome vanadium is referred to it must be appreciated that it has only been tested in the original form of spring and is subject to serious surging, but even under these conditions the failures of chrome vanadium on the rig and on the road are practically negligible. One further point I would like to make clear is whilst we have never failed chrome vanadium on our rigs we have had two failures of springs produced by the Temper Spring Co. made in their new form, in the heat treated and tempered form of carbon steel wire. | ||