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).
The composition and properties of the AC.9 bearing material alloy.
| Identifier | ExFiles\Box 115\5\ scan0218 | |
| Date | 6th December 1938 guessed | |
| 7 These have been extensively tested both for car and aero-engine work and have been found to be even better than the best lead bronze, being much easier to produce and having the added advantage for air-craft use that with a large number of bearings considerable saving in weight was possible. The composition of the typical bearing material, in this case AC.9. is as follows:- " Tin. Nickel. Copper. Magnesium. Silicon. Iron. 5.5-7.0 1.6-1.8 0.6-0.9 0.7-1.0 0.15-0.3 0.2-0.45 The maximum Brinell is about 75, the general figure being between 55 to 75 Brinell. The specific gravity is about 2.95 to 3.00. The co-efficient of expansion 0°C. to 150°C. (.0000225). The heat conductivity about 36.c.g.s. units which is three times that of steel, and five times that of normal Babbitt. The anti-corrosion properties are very good, as indicated by exposure to air, etc., nor is it liable to corrosion as a bearing in contact with oil. The Brinell hardness is only slightly reduced when at 150°C, whereas normal Babbit metal falls from 30 Br.{T. E. Bellringer - Repair Manager} in the cold to about 5 Br.{T. E. Bellringer - Repair Manager} at 150°C." During their research the accepted theories on bearing structures had to be considerably modified, it being found that only successful type of alloy contains a variety of | ||