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 engine bearing performance, testing conclusions, and recommendations for different car models.
| Identifier | ExFiles\Box 115\1\ scan0073 | |
| Date | 19th September 1936 | |
| -3- Naturally bearings that are perfect under 25 HP. speeds and power outputs might behave very differently in the Bentley. Our conclusions therefore are as follows - (a) Our bench tests are not reproducing road conditions. (b) It seems possible that wear on the main bearings in Hall's alloy may have something to do with the big end failure, because on the 25/30 HP. Hall's metal bearings in conjunction with white metal mains have given perfect results so far. (c) It seems probable that our test bed work is unduly hard on white metal main bearings, and that in service these might stand up better than we anticipate. For this reason we recommend that Sr. should try the latest Hall's metal big ends, in conjunction with white metal main bearings. He can do this on his second Trials car which he anticipates will shortly be in for new bearings. Hot weather is the acid test for this combination. Sr. is in a position to inspect the bearings at frequent intervals. If we are to get through our teething troubles on these bearings in a reasonable period, so much running is required that we are bound to use Continental demonstration cars to help out with experimental testing. With regard to customers' cars, there does not seem to be justification at the moment for assuming that the 4¼ litre cars requiring replacements will be more numerous than the 3½ litres, and presumably they can be dealt with in a similar manner. | ||