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 from Dennis Brothers Limited regarding bearing growth and material hardness differences.
| Identifier | ExFiles\Box 116\1\ scan0047 | |
| Date | 9th July 1938 guessed | |
| - 2 - We have not attempted to check the diameter of this bearing, but on the first bearing we found that when it was fitted back in position in the crankcase we could not insert a standard 2.375" plug gauge, this showing that a definite growth had taken place during the period of running. There seems to be quite a distinct difference between the A.C.9. material used for this bearing and the A.C.6., used on our Diesel big ends, and in making the comparative hardness tests by means of a Rockwell B scale we find the relative brinell hardness figures to be 64 for the A.C.6., and 48 for the A.C.9. We will keep you posted regarding the further performance of this type of bearing, and in the meantime should there be any information which you would like to enable you to give the matter your full consideration, we should be only too pleased to forward this on learning your requirements. Yours faithfully, DENNIS BROTHERS LIMITED. [Signature] [Handwritten note] Heat treat for A.C.9. 12 hrs at 180°c R feoric | ||