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 Cadillac Motor Car Co. discussing bearing lubrication issues and material choices.
| Identifier | ExFiles\Box 170\2\ img257 | |
| Date | 6th March 1935 | |
| gy Exptl. Dept. Ha/Rn.{Mr Robinson}6/KW. 6th March, 1935. M.{Mr Moon / Mr Moore} Olley Esq., c/o.{Mr Oldham} The Cadillac Motor Car Co., Detroit, Michigan, U.S.A. Dear Cy., Many thanks for your letter. Re lead bronze bearings - we are asking Coverley to reply regarding the technique of the bearing and have also asked him to let you have a set of 'home-made' centrifugally cast big ends to try. External to the bearing material, we have had several points which caused big end failure. In the first place, even with our 7-bearing crankshaft we found it difficult to get sufficient lubrication into the crank to ensure that all the big ends received an adequate quantity of oil when running at high speeds. Most of the troubles occurred at above 4,000 revs. Normally we feed into the crankshaft at bearings 1, 4, & 7, having a continuous groove in the bearing and three holes in the crankshaft. We found that with lead bronze main bearings and this arrangement, crank pins 2 and 5 were starved of oil. This indicated that the bearings furthest away from the feed into the crankshaft were suffering from oil shortage. We therefore followed up by putting grooves in the intermediate bearings as well as having a continuous feed on all 7 main bearings. This improved matters but after this the big ends generally still seemed not too happy. It appeared that we were asking our gallery pipe to pass more oil than it could manage. We therefore fitted white metal main bearings and were able to go back to our original oiling scheme from bearings 1, 4 & 7 and run quite happily for prolonged periods at 4,500 revs. Since we get very little trouble with our white metal bearings, this is the arrangement we have standardised for the time being. | ||