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).
The work done to resolve issues with the silent tappet mechanism on engine 1.J.III.
| Identifier | ExFiles\Box 106\5\ scan0103 | |
| Date | 14th September 1933 | |
| X5060 To Hor. from Hs{Lord Ernest Hives - Chair}/Wym.{G. Harold Whyman - Experimental Manager} c.c. C. E.{Mr Elliott - Chief Engineer} c.c. Rg.{Mr Rowledge} Hy.{Tom Haldenby - Plant Engineer} Hs{Lord Ernest Hives - Chair}/Wym.{G. Harold Whyman - Experimental Manager}2/KT.14.9.33. SILENT TAPPET MECHANISM ON 1.J.III. The following is a report of work done on silent tappets from 27.4.33. to date. In our last report we pointed out that at the extreme end of each rocker shaft we were short of oil, and so we fixed up an additional feed to each end of both shafts, having four feeds in all, and increased the oil pressure to the rocker shaft to approx. 15 lbs. with the oil temperature at 80°C. This appeared to overcome our lack of oil trouble, but we were still up against the following difficulties:- (a) Steel eccentrics picking up on the rocker shafts. (b) Copper retaining ring for valve in the plunger wearing away and allowing the valve to drop out. (c) Unsatisfactory bedding of the valve on the plunger seat. (d) Plunger springs breaking. To overcome trouble (a) we tried a set of cast iron eccentrics E.58576, of the same dimensions as the steel ones, but as per our report of 19.6.33., these broke across the oil feed hole after only a short run on the test bed. The next eccentric design was of cast iron considerably strengthened E.59589/90, with the oil feed hole deleted. After a few runs on the road these were dismantled for examination, and were found to be still picking up on the shaft, so we tried an annular groove .062" x .010" at each oil feed hole on the shaft. This appeared to help matters, but did not cure the trouble altogether, so we had a similar sized groove machined horizontally in the top and bottom of the shaft connecting with the annular groove, the length of same being 1.000". <--.5--><--.5--> | ||