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).
Design and testing of new strengthened barrel-type tappets for the Phantom III engine.
| Identifier | ExFiles\Box 96\2\ scan0302 | |
| Date | 9th May 1939 | |
| DY{F R Danby}/MS c. Rm.{William Robotham - Chief Engineer} c. Huy/S c. RHC{R. H. Coverley - Production Engineer}/VS{J. Vickers} DA.{Bernard Day - Chassis Design}1/G.9.5.39. 354. PHANTOM III. BARREL TYPE TAPPETS. Please receive herewith :- E.CD.1361 Strengthened Tappet - Phantom III. In view of the failure of some of the tappets by fracture, as reported in Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}9/MH.{M. Huckerby}1.5.39, we have considerably strengthened the tappet by increasing the thickness of metal on the barrel diameter and the base, the core slots have been replaced by small circular core holes and the oil drain hole near base of tappet is deleted altogether. These modifications have been discussed between RHC{R. H. Coverley - Production Engineer}/VS.{J. Vickers} and Da{Bernard Day - Chassis Design}/Mc.S. and should be satisfactory from the Foundry point of view. Regarding the suggestion to increase the rotation moment of tappets by widening the cams, this will mean reducing the length of the camshaft bearings by corresponding amounts, and we suggest that further running with the improved tappets should be carried out before making this change. With reference to the proposal to try a 1.000" diameter tappet on the Wraith III engine, we would point out that the cam base circle is much smaller on the Wraith III than on the Phantom III, and would result in a sharp nosed cam form and possibly loss of lift due to interference between opening and closing forms. The new tappet is approximately 1/2 oz. heavier than the previous tappet to E.CD.821. We notice that the position of two of the core slots on the broken tappets E.89388 is much nearer the base of the tappet than the design shows, also the .125 diameter drilled drain hole is altered to .200 diameter cored hole, both of these alterations having a weakening effect on the tappet. Will you please detail and instruct the new tappets experimentally as soon as possible. DA.{Bernard Day - Chassis Design} | ||