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).
Technical memorandum discussing the performance and issues with Hall's metal bearings on Bentley engines.
| Identifier | ExFiles\Box 146\3\ scan0082 | |
| Date | 21th September 1936 | |
| W/P - Sr. X1020 Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}9/KW.21.9.36. Attached is a copy of a note I circulated on Bentley bearings. Re Hall's metal bearings on 15,000 miles tests, actually those at present running have completed 14,000 miles, and on one of the last runs an average of 60 M.P.H. was maintained. We agree that one of the big end bearings failed at 10,000 miles, but from its appearance I think that at some time or other the engine had been over-revved. Anyhow the big end bearings are easy, and we have a much better variety than the original alloy on test. I think the worst trouble has been that the little shims between the two halves of the bearings are steel with the tin-aluminium alloy stuck to them, and this breaks away, which does not do the bearing any good. There is no reason why these shims should not be made in Hall's alloy, which we think will improve matters a great deal. You will see that we have suggested that you run white metal main bearings as you had such success with these on the 3½ litre. We would warn you to examine them fairly frequently, however - round about the 10,000 miles mark. Briefly, whilst we appreciate your alarm we do not see why you should have any more trouble with the 4¼ litre than with the 3½ litre with white metal bearings. By the time your car has done 15,000 miles we shall be able to give you a better Hall's metal big end to put in owners' cars. If the main bearings want changing we shall have something to offer in their place, but we do not expect main bearings to give trouble in less than 20,000 miles, if then. If you change the main bearings on your green Trials car we should like you to satisfy yourself what their condition really is before you send them back to us. We do not think they are as bad as you imagine. | ||