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).
Investigation report into the failure of Bentley crankshaft main bearings during testing.
| Identifier | ExFiles\Box 115\3\ scan0090 | |
| Date | 15th November 1937 | |
| Files SWDZ 1020 To BY.{R.W. Bailey - Chief Engineer} & Rm.{William Robotham - Chief Engineer} Hs.{Lord Ernest Hives - Chair} & Mx.{John H Maddocks - Chief Proving Officer} LA.{L. A. Archer} Hd.{Mr Hayward/Mr Huddy} RHC{R. H. Coverley - Production Engineer}/Cy.1/FH.15.11.37. FAILURE OF BENTLEY CRANKSHAFT MAIN BEARINGS. On Friday 5th. inst; two engines failed on test and on examination of the cause it was found that the bearings had seized. The oil supply was tested and found to be normal and adequate. The conditions of assembly were also normal and up to the required standard. The system by which we control the heat treatment and machining is that all pots and bearings after both heat treatments are marked with green paint. Every Pot is tested for hardness and later every bearing. There are two special operators only who handle this job, and they have very definitely been instructed not to pick up either pots or bearings for machining unless they have been marked with this green paint. This instruction is rigidly carried out. A laboratory examination was made of the bearings and they were found too low on Brinell (see report), and on further investigation the bearings responded to heat-treatment and came up to the required figure. It was suggested that the bearings had not been originally heat treated. In this we do not agree. The Bearings had become heated sufficiently during running to "blue" the caps, and there is a difference of opinion between H.L. and Mr.Talbot as to whether or not the heat generated in seizing while running has softened the bearings. In confirmation of the suggestion that the bearings are being softened in running it was found that a thrust bearing which showed signs of seizing on the flange faces gave a Brinell of 81.5 on the back of the bearings, and a figure of 54.5 on the flange faces. We have now 12 engines in various stages of dismantling so that all bearings can be checked for Brinell. The Bearings of seven of these engines have been Brinell tested and all except three bearings are within the 73 figure, the remaining three bearings are 69 approximately. This further supports our contention that all bearings have been heat treated. continued over.- | ||