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).
Letter to Ariel Motors Ltd. regarding the composition and properties of two bearing material alloys, RR.AC.6 and RR.AC.7.
| Identifier | ExFiles\Box 115\5\ scan0009 | |
| Date | 16th March 1938 | |
| For your information. R.{Sir Henry Royce} Royce - 10209 FB/EHF. 51690 16th March,1938. Dict. 15..38. Messrs.Ariel Motors Ltd., Ariel Works, Selly Oak, Birmingham, 29. Dear Sirs, Attention of F.{Mr Friese} Anstey,Esq. We thank you for the courtesy extended to our representatives when calling upon you on Thursday last, the 10th inst., when we briefly discussed the new RR.AC.6. bearing material alloy, which is produced by High Duty Alloys Ltd., of Slough, the bearings being manufactured by Wellworthy. We confirm that there are two materials used for this bearing, that is RR.AC.6. and RR.AC.7. The latter has been modified slightly for use with comparatively soft shafts, as it was originally intended that this material would be used only on hardened shafts, having a Brinell figure of minimum 600. The general composition of these two materials is as follows - Nickel Manganese Tin Antimony Magnesium Silicon Iron AC.6..... 1.7% 0.7% 5.0% 0.50% 0.9% .50% .3% AC.7..... 1.7% 0.7% 5.0% 0.50% 0.45% .50% .3% The approximate figures covering specific gravity and co-efficient of expansion are as follows - Specific Gravity ....... 2.95 to 3.00 Co-efficient of expansion ........ 0°C. to 150°C. .0000225. | ||