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).
Comparative tests of lead bronze main bearings from Allison and Rolls-Royce.
| Identifier | ExFiles\Box 173\1\ img404 | |
| Date | 2nd February 1934 | |
| To HS{Lord Ernest Hives - Chair} from RHC{R. H. Coverley - Production Engineer} Copy sent to Allison Engineering Company Indianapolis, Indiana February 2, 1934 R R BEARING TESTS. Comparative Tests of Allison and Rolls Royce Lead Bronze main bearings were conducted under identical test conditions. Tests were run on P 4 Oil. The Allison bearings completed twenty minutes running at 3500 R.P.M. at Oil Temperature 90 C and run satisfactorily under steady Oil Pressure and temperature conditions. Corrected bearing temperature figures show centre bearing reached maximum temperature of 132 C at 3250 RPM. Torque increased from 18 lbs. to 25 lbs. at completion of five minutes running. At this speed conditions were normal. (See sheet.) Speed was then increased to 3500 R.P.M. General conditions remained constant for 10 minutes, there being no increase in torque. At completion of this period test was stopped to check Oil Gauge which was found to be faulty. After replacement test was continued under same speed and temperature conditions for a further ten minutes period. Torque constant at 17-18 lbs. Examination of bearings at completion of test showed slight evidence of lead sweat on centre bearing, which was believed to have been caused when torque increased at 3250 R.P.M. General condition of bearing was however considered to be very satisfactory, particularly since the finish prior to test was not of a very high standard, and bearings were considered fit for further tests. R.R. produced bearings were then fitted and run under similar conditions. Partial failure occurred after 2½ minutes' running at 3000 R.P.M. Oil pressure dropped to 40 lbs in. and bearing temperatures rose rapidly. Torque increased from 18 to 40 lbs. However, owing to a misunderstanding, dynamometer was stopped; otherwise complete failure would have occurred. Test was continued and 5 minutes at 3000 R.P.M. completed. After running 2½ minutes at 3250 R.P.M. complete failure occurred. Sudden rise in bearing temperature to 200 C. Oil pressure drop to 40 lbs. in. and torque increased to 85 lbs. Examination showed centre bearing to have seized and crank shaft badly discolored. | ||