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).
Main bearing failure in car 22-0-V, comparing performance with Bentley bearings and suggesting design improvements.
| Identifier | ExFiles\Box 101\2\ scan0197 | |
| Date | 2nd December 1936 | |
| 500a Hs.{Lord Ernest Hives - Chair}from Rm.{William Robotham - Chief Engineer} c. to Sg.{Arthur F. Sidgreaves - MD} c. to E.{Mr Elliott - Chief Engineer} c. to By.{R.W. Bailey - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} c. to RHC.{R. H. Coverley - Production Engineer} Rm{William Robotham - Chief Engineer}3/R.2.12.36. 22-0-V.{VIENNA} You will see from the attached report that the main bearings on 22-0-V are now beginning to fail. This car has covered about 25,000 miles with the new bearings. 15,000 miles of this was normal high average speed Continental work, the last 10,000 has been on research work, and really about equivalent to English conditions. During the high speed running we have no record that the oil inlet temperature exceeded 100°C, which is quite a low figure compared with the Bentley. On Continental work the Bentley constantly exceeds 120°C. This is the first figure of merit we have been able to obtain on white metal bearings with a 25/30 engine. It is of considerable interest because on our bench tests the Bentley will run out a set of white metal bearings in 20 hours, whereas the 25/30 will last between 60/80 hours; in other words, we should expect a Bentley with our standard white metal main bearings to last less than 10,000 miles in France. It will be interesting to see whether Sr. confirms this figure. It is not very far from our original estimate, and this is why we went to Hall's metal main bearings on the Bentley. In addition to the information from our experimental car, we have just received some figures from Slater taken from a 3½-litre Bentley which has covered about 28,000 miles on white metal main bearings. These figures shaft show that the centre bearing has worn .005. As far as we know at present there is no bearing material which is kinder to the crankshaft than white metal bearing. Our conclusions, therefore, are that we have got to have more main bearing area as quickly as possible. On the present figures, if we get the bearing to stand up, crankshaft wear will still be excessive. Several designs for larger crankshaft journals have been got out in the past, but have not been proceeded with, because, at the time, the modification could not be justified. | ||