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).
Issues with Maxium pistons containing 10% copper, specifically their tendency to collapse and knock.
| Identifier | ExFiles\Box 66\1\ scan0131 | |
| Date | 28th February 1927 | |
| To BY.{R.W. Bailey - Chief Engineer} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} x40740 RE. MAXIUM PISTONS - 10% COPPER. x4044 The first set of this type of piston were pedestal, split in the normal manner. We find that they collapse and therefore knock. We have proved that they collapse considerably more than the std. alum. piston in the ratio of about 4 to 1. As far as we can judge the co-efficient of expansion of this material is 22 X 10-6, therefore we do not see the slightest prospects of any results if we run the pistons without a split in the skirt, as we shall have to allow a great deal more clearance than we used on the cast iron type, and these were bad enough for knocks. As far as we can see, the elastic limit of the material dictates whether or no the piston will collapse. In any case it would be of interest to have the makers figures on this material and at the same time get their views on whether they can produce anything which is likely to give a better result. We do not wish to alter our piston design by putting a ring in the skirt to increase the rigidity thereof if we can avoid it. He/Rm{William Robotham - Chief Engineer} | ||