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).
Results of multiple bearing and cage tests, numbered 8 to 13, and conclusions drawn.
| Identifier | ExFiles\Box 115\2\ scan0594 | |
| Date | 14th December 1937 guessed | |
| SHEET 2. TEST No.8. The same bearing and cages now ran under increased loads, i.e. 2030 lbs. (J) and 2200 lbs. (T) loads at 1000 R.P.M. for a period of 100 hours satisfactorily. Max. Temp. Rise: 65°F.{Mr Friese} Normal Temp. Rise: 60°F.{Mr Friese} TEST No.9. Under the same conditions of load but the speed reduced to 500 R.P.M. the bearing again ran for 100 hours with excellent results. Max. Temp. Rise: 76°F.{Mr Friese} Normal Temp. Rise: 71°F.{Mr Friese} TEST No.10. Bearing fitted with bakelite cages having cage clearances of .006" ran for 100 hours at 500 R.P.M. 2030 lbs. (J) and 2200 lbs. (T) loads. Examination found the cages had shrunk and had rubbed slightly upon the shoulders of the inner, otherwise they were O.K. Max. Temp. Rise: 56°F.{Mr Friese} Normal Temp. Rise: 51°F.{Mr Friese} TEST No.11. A bearing without cages with outers tilted .004" was rotated by hand and the gap between a given pair of balls was measured by feelers. The acceleration and deceleration between balls was found to be a maximum of .016" with a mean of .013" for each revolution of the balls round the outer track. TEST No.12. A bearing fitted with steel cages (C.C. .006) the ball holes of which were elongated .025" and the sides weakened 50% now ran at 3000 R.P.M. under 1050 lbs. (J) and 1420 lbs. (T) loads, these being equivalent to 63 M.P.H. in top gear with the 3-1/2 litre engine and were considered the most representative for a duration run. After a satisfactory run of 500 hours the cages were in excellent condition. Max. Temp. Rise: 122°F.{Mr Friese} Normal Temp. Rise: 95°F.{Mr Friese} TEST No.13. A similar bearing to the above but having full strength cages was run under identical conditions for 500 hours. On examination the bearing was in excellent condition but a slight shortage of oil had caused a light rub in the bore of the thrust side cage, otherwise both cages were O.K. Max. Temp. Rise: 101°F.{Mr Friese} Normal Temp. Rise: 84°F.{Mr Friese} N.B. These were the same cages used in Test No. 6. CONCLUSIONS DRAWN FROM TESTS. Although steel cages having standard ball holes and .020 shoulder clearance and also bakelite cages gave successful results, for practical reasons it is not desirable to use these on this application. From tests Nos. 4, 5 and 6, it will be seen that the most satisfactory results were obtained with steel cages having ball holes elongated .025 and this has been verified by the results from tests 12 and 13 where cages of this type ran satisfactorily for 500 hours. | ||