Proposal sheet No. 51 detailing adjustments to piston bedding to address engine knocking.
| Identifier | ExFiles\Box 81\2\ scan0125 | |
| Date | 22th February 1924 | |
| Oy8-E-22524 February 22, 1924. Mr. Claude Johnson, Rolls-Royce, Ltd., London, England. (Copy for attention of Mr.Royce " " " " Mr.E.Platford " " " " Mr.E.Hives) Dear Sir: Re: Proposal sheet No.51 Piston Bedding. It was noted that in certain cases pistons would knock and show bright bedding on lower ring bands on the gudgeon pin diameter, showing that they were moving from side to side in the bore. First the band above the scraper ring was reduced from 4.490 dia. to 4.485 dia., but knocks continued. It was noticed that the more the skirt bedding could be brought round the sides of the skirt at the bottom, the freer we were from knocks and from bright marking on the sides of the ring bands. We therefore adjusted the throw and taper of the eccentric grinding, to give 15 thousandths undersize at the top of the skirt on the pin diameter with a bearing band about 1-3/4" wide on the cross diameter and to run out about 1/4" from the bottom. The shape of the eccentric grinding and bearing band is approximately as shown. These pistons we find are very free from knocking, change very little in shape on the dynamometer, and require no filing, except that in certain cases where the bearing shows slightly hard after dynamometer, a slight easing of the corners at points marked A is required. This proposal is to continue with this form of bedding. Oy. M. {Mr Moon / Mr Moore} Olley O {Mr Oldham} /= | ||
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).