Investigation into scoring and wear issues on Phantom III tappets.
| Identifier | ExFiles\Box 96\2\ scan0296 | |
| Date | 4th October 1938 | |
| 354. Rm. {William Robotham - Chief Engineer} from Mx. {John H Maddocks - Chief Proving Officer} Mx. {John H Maddocks - Chief Proving Officer} 12/G.4.10.38. PHANTOM 111 TAPPETS. It is clear from evidence now available that deleting the hydraulic mechanism has not overcome scoring and wear of chromium faced tappets. Several instances have occurred on chassis on test, and there have been two recurring cases on customers cars, which have been converted to non-hydraulic tappets. The following points have been established:- (1). There is no shortage of oil under any running or standing condition, the camshaft being almost entirely submerged in an oil bath. Tappets and cams are well lubricated with Keenolised grease when assembled, and the camshaft well is filled with oil. (2). Wear occurs on both inlet and exhaust tappets, and is not peculiar to any particular tappets in an engine. (3). We have tried increasing the oil leak from the bottom tappet and its guide by the use of squared washers and thus eliminating the possibility of an hydraulic ram effect. On one engine so treated four tappets were found to be scored, two inlet and two exhaust. One of these tappets was scored on the leading edge and not at the point of maximum lift. (4). There is no evidence that scoring is due to poor quality chromium plating. (5). Hardness of the chromium plating is not a factor. Scoring occurs on tappets on which the hardness ranges from 585 to 720. (6). Finish of Camshafts. Examination of the Fh.111 camshaft under the Bio-microscope shows the finish to be comparable with other similar parts, having a ground finish. We might try tinplating or copper depositing the cams, to see whether any advantage can be gained. There are a number of cars in service, which are apparently not giving any trouble in this respect, and twelve months ago (see Rm. {William Robotham - Chief Engineer} 29.10.37) a total of 252,033 | ||
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).