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).
The performance and testing of engine main bearings and big end bearings for Bentley and 25/30 HP units.
| Identifier | ExFiles\Box 115\1\ scan0072 | |
| Date | 19th September 1936 | |
| -2- (3) Hall's Metal Main Bearings on 4¼ litre Bentley Engine. It was at once apparent on the 4¼ litre engine that the extra power output meant that the white metal main bearings were overloaded, and therefore we were forced to develop a new main bearing material. Lead bronze has not worked at all on the main bearings. After a lot of preliminary work, we got a Hall's alloy bearing which stood up well. We have just completed 265 hours on the test bench and 5,000 miles on the road on one set of these bearings, which we have previously had reason to believe is equivalent to at least 150,000 miles running under French conditions. These are the bearings which are standardised, and have shown signs of failure after 15,000 miles on Sr's Paris demonstration car. The inspection of the bearings at the conclusion of the first 15,000 miles test on E-56-BN{W.O. Bentley / Mr Barrington} indicated that they were worn, but not to the extent at first suggested. (4) Big End Bearings in Hall's Alloy on the 4¼ litre Bentley Unit. We had occasionally experienced failures of lead bronze big end bearings on test bench running. Aero work has also confirmed that this material is somewhat capricious in its behaviour. The large clearance necessitated with lead bronze is also a disadvantage with regard to oil consumption. We therefore developed big end bearings in Hall's alloy. So far in nearly 1,000 hours' test bench running we have never had a big end failure in this material. In spite of this we have had failures of big ends on both the 15,000 miles tests run in France. 25/30 HP. (1) White Metal Main Bearings & Hall's Metal Big Ends on the Big Bore 25/30 HP. Unit. The oil temperature on the 25/30 never gets as high as that on the Bentley because of the lower specific power output. For this reason we decided to stick to white metal main bearings on the 25/30 and use Hall's metal big ends only. The first test on this combination in France is still running on 22-G-V.{VIENNA} (2) Hancock reported after 15,000 miles' running that the bearings were perfect. We attach a copy of his memo. as it was not circulated to all concerned. | ||