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).
Experiments with solid aluminium-tin bearings, including material composition and test results.
Identifier | ExFiles\Box 115\1\ scan0002 | |
Date | 1st January 1938 | |
-2- The next experiment was to run these bearings without steel shells in the solid aluminium-tin material. The composition of those tested was - 7% Tin 1.9% Nickel .75% Manganese .35% Magnesium The remainder aluminium. The Brinell is 48, the melting point 600°C. The big end bearings have so far been entirely satisfactory in this material, though we have only run for a period of 70 hours. The main bearings were fitted up with white metal clearances, and this proved to be too close. The clearance was increased from .0025" to .003" and the results up to date have been entirely satisfactory. It is of course a considerable risk to go into production with a bearing with which we have had, relatively speaking, so little experience. On the big bore Bentley, however, we have no alternative but either to fit this alloy which gives promise of being satisfactory, or to fit white metal bearings which we know will fail if driven hard. We have been in communication with Leylands, who have been running aluminium alloy bearings direct on the hardened shafts for 2 or 3 years, and they encourage us by saying they have had little or no trouble. Furthermore, we have had considerable experience of aluminium alloy connecting rods running directly on the shaft, and these showed that aluminium was a reliable bearing material. Under the circumstances, since there is no chance of getting a 15,000 miles test on Hall's material before the big bore Bentley is in production, we have no alternative but to recommend the solid Hall's metal bearings on existing experience. In the case of the big bore 20/25, we recommend Hall's metal bearings for the big ends, and white metal mains. We are aware that on our 10,000 miles tests we can run out our white metal mains, but think it exceedingly unlikely that the average customer who buys a 20/25 HP. will run into serious trouble. If the aluminium alloy bearings come up to our expectations on the Bentley, we should recommend changing over on the 20/25 as soon as we have completed the necessary road running. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||