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).
Failures of big end bearings on the 4 1/4-litre engine and the testing of a new, thinner Hall's alloy bearing on the Phantom III and Wraith engines.
| Identifier | ExFiles\Box 115\3\ scan0024 | |
| Date | 25th July 1937 | |
| 1020 also 1260 By.{R.W. Bailey - Chief Engineer} from Rm.{William Robotham - Chief Engineer} c. Hs.{Lord Ernest Hives - Chair} c. RHC.{R. H. Coverley - Production Engineer} c. Da.{Bernard Day - Chassis Design} Rm{William Robotham - Chief Engineer}1/R.25.7.37. BIG END BEARINGS - ALUM. TIN ALLOY. The most alarming thing about big end bearing failures on the 4 1/4-litre engine in service, is that the result is invariably a wrecked engine. When we wreck a strip bearing big end on the test bed, we sometimes hardly know it has failed. The trouble appears to be due to the use of a bearing .125 thick on a rod carrying a piston with only .075 clearance between the crown and cylinder head. Of necessity, to get Hall's alloy into the existing P.III con rod, we had to run the material .062 thick. These rods have now completed 60 hours endurance at speeds up to 4,500 R.P.M. at full throttle and under light load. We are carrying out tests on a similar bearing thickness on Wraith, and shall actually cut off the oil supply at speed on an engine. If the con rod does not come through the bottom half, then we think we should go for this bearing at once on Wraith. A minor point is that the thin bearing does away with shims, which we believe the Works like, and is dowelled in position, which we believe saves cost. Rm.{William Robotham - Chief Engineer} | ||