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).
Issues and experimental solutions for flat bottom tappets on Wraith and Bentley engines.
| Identifier | ExFiles\Box 158\4\ scan0228 | |
| Date | 10th May 1938 | |
| To By.{R.W. Bailey - Chief Engineer} c. to Hs.{Lord Ernest Hives - Chair} c. to Da.{Bernard Day - Chassis Design} c. to RHC.{R. H. Coverley - Production Engineer} c. to W/JNR.{Charles L. Jenner} c. to Da{Bernard Day - Chassis Design}/Mc'. 1360 Rm{William Robotham - Chief Engineer}/wdl.1/JH.10.5.38. FLAT BOTTOM TAPPETS AS APERTAINING TO WRAITH III, BENTLEY III & BENTLEY 50. Trouble was experienced with the original Wraith scheme of flat bottom tappets due to the fact that the tappets did not rotate with the result that the faces scuffed. These were in S/W with the push rods housed at the top of the tappets and a resultant off set movement of .100" of the cam on the tappet. In order to make them a workable job the American principles were adopted en bloc' and consisted of the following (a) Push rod housed in the base of the tappet to reduce side thrust to a minimum. (b) Tappet material altered to T/C with chilled hardened face. (c) Inclined tappet with conical face to increase the moment of rotation. As proved by the 20,000 miles test the tappets are now a satisfactory proposition and further experiments we have carried out have been done primarily for information for R.50 engine to see if a successfull tappet could be made using a vertical tappet having a flat face. In order to analyse the American principles our first experiment was to use a vertical tappet with a flat face as original R.R. scheme but retaining the push rod in the base of the tappet and the latter in T/C material. | ||