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).
Engine component issues, specifically worn camshafts, tappets, and sticking rockers on the Phantom III model.
| Identifier | ExFiles\Box 131\3\ scan0097 | |
| Date | 22th June 1939 | |
| - 2 - Mx{John H Maddocks - Chief Proving Officer}1/MG.22.6.39 (continued) 1. Worn Camshafts and Tappets on Ph.III It was felt some little time ago that this was a problem which had not been solved by the deletion of the hydraulic tappet mechanism, and that we should be faced later on by the necessity for expensive renewals of camshafts and tappets. Recent experience proves that this looks like materialising, as some £600. has already been spent by Depots in renewing camshafts without any permanent results. The Exp. Dept. are developing a scheme for fitting Wraith type barrel tappets to existing Ph.III cars, and this shows considerable promise for application where the camshaft has to be replaced. Concurrently with this, we have been encouraged to carry out further investigation work based on the knowledge that some Ph.III cars manage to run big mileages without tappet trouble; also some tappets on an engine which may have an otherwise deplorable collection of scored cams and tappets may be perfectly all right, indicating that there are conditions present which have not been understood and which may vary from one engine to another, or from one tappet to another. In order to study these conditions, we have borrowed from "S" an ex-Trials car, and we have been able to make a certain amount of progress. Unfortunately we have now had to part with the engine in order that it could be used to replace that in Mr. Becker's car which was suffering from a mysterious knock which had defied all attempts to cure it (See later remarks on this subject). We are now faced with the job of locating and curing this knock before we can proceed with the tappet experiments again, but the engine is being built up and is to be run on the unit bed to facilitate investigation. 2. Sticking Rockers & Eccentrics. Ph.III This has always been a trouble after a car has run, say, 30,000 miles, as wear and the accumulation of carbon introduce lubrication and other difficulties which upset the functioning of the hydraulic mechanism. We also have evidence that incorrect functioning of this mechanism re-acts on the bottom tappets. Depots are spending some £20. a month in dealing with noisy and sticking hydraulic mechanism, but it is hoped to clear this trouble by our work on the Phantom III car referred to above. (continued) | ||