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).
Reliability of big end bearings and the testing of alternative materials like tri-metal and lead-bronze.
| Identifier | ExFiles\Box 159\5\ scan0100 | |
| Date | 26th November 1940 | |
| Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation} from Rm.{William Robotham - Chief Engineer} Rm.{William Robotham - Chief Engineer}10/ML.26.11.40. BIG END BEARINGS. Confirming our conversation with you on big end bearings. The present position is that we are running A.C.9. big ends in all production models. This is a remarkable bearing as long as it gets lots of clean oil. It's one fault is that if anybody forgets to put oil in the engine, or the oil pipe breaks, a bearing will fail and, owing to the fact that the connecting rod in steel will then run on the steel crankshaft, the engine will probably be wrecked. When we go to cheap cars, the owners can be expected to neglect them and when they run big ends we do not want them to scrap their engines. For this reason, we are anxious to get satisfactory connecting rod bearings in either tri-metal Vandervell or lead-bronze Vandervell. We think it very possible that a tri-metal will not stand up to the load, since you will remember that the 3 1/2 litre Bentley white metal bearings failed in about 60,000 miles and since then we have increased the engine displacement to 4 1/4 litres, and also cut down the width of this particular bearing. A 25 hour test on the bench at 4,000 r.p.m. comparing three lead-bronze with three tri-metal, should give us a line on their respective durabilities. If the white metal will not stand up, then we shall have to run lead bronze on a lot of cars onthr road to see if there is any trouble with corrosion. We know from the Leyland's installation that the Vandervell lead bronze will stand considerably more load than tri-metal. Rm.{William Robotham - Chief Engineer} | ||