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).
Manufacturing difficulties with the Bentley 80 Crankshaft, EB.4104, regarding oil caps and taper plugs.
| Identifier | ExFiles\Box 123\5\ scan0130 | |
| Date | 25th October 1938 | |
| 1044 To Da.{Bernard Day - Chassis Design} from HPS.{Horace Percy Smith - Experimental Factory Mgr} c. BY.{R.W. Bailey - Chief Engineer} c. Da{Bernard Day - Chassis Design}/Hdy.{William Hardy} C. Rn.{Mr Robinson} C. RHC.{R. H. Coverley - Production Engineer} HPS.{Horace Percy Smith - Experimental Factory Mgr}7/VS.{J. Vickers}25.10.38. BENTLEY 80 CRANKSHAFT EB.4104. Confirming our verbal report to Da{Bernard Day - Chassis Design}/Jnr.{Charles L. Jenner}, it has been found impossible to make a satisfactory seal using the pressed steel oil caps for which provision has been made in the above crankshaft. A certain amount of leakage cannot be avoided, and previous experience has shown that pressed-in discs tend to become loose under the effects of vibration. Furthermore, discs cannot be completely flattened in assembly owing to lack of a solid backing, the grooving of crankpin and journal diameters is a difficult machining operation and the removal of discs for periodical cleaning of oil passages is not as easy as it should be from a service standpoint. Reversion to the ordinary cone type oil cap is therefore recommended, and in view of the fact that the first of these shafts is now approaching completion we are anxious to obtain a revised detail drawing as quickly as possible so as not to hold up manufacture. We attach hereto a copy of W. Bell's report on tests which have been carried out in this connection. There is one other point in connection with this crankshaft, and that is difficulty is being experienced in obtaining taps of the correct size for the taper plugs in the oil feed passages. Taps will have to be made specially and there may be some delay in completing the first shaft unless you would be agreeable to adopting the same size of plug as that which is used for the Phantom III connecting rod. The tapping size in that case is No.1 Briggs Pipe Thread, and taps of this diameter can be obtained from stock. HPS.{Horace Percy Smith - Experimental Factory Mgr} | ||