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).
Recommendations for engine modifications B and C concerning bearing problems, including labour hours and fitting instructions.
| Identifier | ExFiles\Box 107\2\ scan0126 | |
| Date | 23th May 1938 guessed | |
| -2- Either of the modifications B. or C. are invariably carried out in conjunction with an R.10 or R.20 for which the customer pays. It is recommended that when an engine is dismantled for an R.20 modification C. should be carried out. It is not good policy to effect Mod.B. in conjunction with an R.20. In fact Modification C. carried out with an R.10 which is usually needed after one years service would in the long run be the most economical, and undoubtedly the best method of dealing with the bearing problem. The comparative extra labour hours for the Mod.B. and C. are as follows: Mod.B. in conjunction with R.10 extra hours 46 1/2 Mod.C. " " " R.10 " " 136 approx 78/0 Mod.C. " " " R.20 " " 100 approx 56/10/0 With regard to material it is very seldom necessary to replace the main bearings when Mod.C. is done. In addition to the previous instructions for Mod.C. the following should be added: (a) Adopt the works method of forcing the bearings into the housings to ensure correct bedding of the back of the shells. (b) "Nip" - This should be .001" at each side of the bearing relative to the joint face on both halves. Before the bearing is clamped up, therefore, the bearing shells stand proud of the housings by this amount on each of the four joint faces giving a total nip of .002. (c) The No.7. main bearing should be in white metal with white metal faced steel liners. As this bearing has a steel backing there is no necessity to force the bearing in position as outlined in (a). The total nip of this bearing should not be more than .001. | ||