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).
Comparative performance and potential failures of different exhaust valves.
Identifier | ExFiles\Box 106\5\ scan0156 | |
Date | 25th April 1936 | |
X554 To R.{Sir Henry Royce} c. to Sg.{Arthur F. Sidgreaves - MD} c. to Wor.{Arthur Wormald - General Works Manager} c. to By.{R.W. Bailey - Chief Engineer} c. to RHC.{R. H. Coverley - Production Engineer} c. to Sft.{Mr Swift} c. to Da.{Bernard Day - Chassis Design} Es/Rm.{William Robotham - Chief Engineer}J/KW.25.4.36. 22-C-V.{VIENNA} Referring to E.2/HP.17.4.36 and E.2/HP.15.4.36. We have sent 22-C-V to France with 3 of the exhaust valves similar to the Bentley which have been instructed for production, and 3 of the new tulip type exhaust valves to LeC4915 which have never previously been run. The reason we have done this is because we are not altogether confident that the Bentley valve will prove satisfactory in the 20/25. The reasons for this are as follows :- (1) The 20/25 valve failed under English running conditions in spite of the fact that it was made of KE-965 steel. English running conditions are far less severe than Continental conditions. (2) Since we have only had one previous failure of this design of valve on our 15,000 miles tests when the valve was made in silchrome we should have expected it to stand up much longer than this in KE-965. It should be remembered that we had a failure of the Bentley type of valve on a 15,000 miles test when it was made in silchrome, and all we did to it was to make it in KE-965, since when we have never broken one on the road. (3) A long time ago we tried to use austenitic steel exhaust valves on the 20/25, and again found that those valves seemed to be having a worse time than they did on the Bentley because at the time we could not persist with the steels. There seem to be 3 reasons why the 20/25 valves may be worse off than the Bentley - (1) The camshaft is of the long toe type which limits the time when the valve can get heat of its head through the valve seat. | ||