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).
Improving main engine bearings, discussing lubrication, clearances, and new metal alloys.
| Identifier | ExFiles\Box 173\2\ img036 | |
| Date | 6th July 1931 guessed | |
| Page #2 If plain bearings with external groove and additional oil holes provide sufficient crank pin lubri- cation, improved main bearings will result as oil will be more uniformly distributed and there being less risk of oil film breakdown. Heat to oil will be less and if bearing clearances can be reduced, oil consumption will be more readily controlled and reduced clearance would make it possible to retain the present capacity oil pumps. Allison's strongly recommend 100#/sq.in. minimum pressure and consider under these conditions with the increased Brinnel hardness of crankshafts already re- ported, bearing clearances can be reduced from .0045 to .003-.0035 for main bearings only. Should tests prove drilling of all crank webs to be desirable, it would perhaps mean drilling webs at right angles owing to the elongated holes that would be necessary by present layouts. (See sketch). With regards to main bearing test, it would be useful to conduct a series of tests with the bearings loaded with metal that has not previously been alloyed, with copper of 99.5% purity and lead of 99.9% purity in proportions of 70/30 with 1% silver addition. The reason for the latter is because it is found to flux and give a more homogeneous condition of bearing metal. More information on the production of bearings will be given in my next report. R A Coverley | ||