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).
Bentley engine bearing wear, performance, and material testing.
| Identifier | ExFiles\Box 146\3\ scan0147 | |
| Date | 29th October 1936 | |
| To Sg.{Arthur F. Sidgreaves - MD} from Hh. C. to Hs.{Lord Ernest Hives - Chair} C. to H.{Arthur M. Hanbury - Head Complaints} C. to By.{R.W. Bailey - Chief Engineer} C. to Sr. C. to Hd.{Mr Hayward/Mr Huddy} 1020 Rm.{William Robotham - Chief Engineer}7/AP.29.10.36. BENTLEY ENGINE BEARINGS. We have now had an opportunity of discussing the position with Sr. We have examined the figures obtained from the 2nd. Paris Trials Car which was stripped, we have also examined Raymond May's car which has now covered 22,000 miles on these bearings and was driven to capacity. From these figures only a small amount of wear has taken place either in the crankshaft or the bearings on the Paris Trials Car, in fact we rather doubt that the roughness complained of could have been due to this particular cause. Raymond May's bearings seem to be in quite good condition apart from one big end shim which is breaking away. We are replacing these shims with RR.56 material, for which we have already circulated a standardisation sheet. We tried the car on the road for roughness complained of before dismantling. There was a certain amount of engine period, but we agree with the Repair Department that the engine cannot be considered rougher than the average 3½ litre as when it is first turned out. It remains to be seen whether the period will get worse. Therefore, summarising the information we have obtained from the 4¼ litre Bentleys we have examined, we are still of the opinion that they should not give appreciably more bearing trouble in service than the 3½ litre. On the development side we have found that if we run at maximum speeds with the lightest throttle opening that will turn the engine over, we can fail a bearing in three hours which would previously run 250 or more under full throttle conditions. We have already found that under this lightened throttle running the forged alloy will give about three times the life of the material we have standardised. In parallel with the tests on Hall's alloy, Sr. is running whitemetal on one of his trial cars to get figures of merit for these, and we are experimenting with improved whitemetal bearings from the Hoyt Co. and from the Cleveland Graphite Co. U.S.A. continued. | ||