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).
Letter from a bearing supplier detailing test results and proposing a change to bearing pre-load specifications.
| Identifier | ExFiles\Box 94\2\ scan0287 | |
| Date | 24th September 1937 | |
| RANSOME & MARLES BEARING Co., Ltd. - 2 - S. H.{Arthur M. Hanbury - Head Complaints} Grylls, Esq., Rolls-Royce Ltd: 24-9-37 conversation that this matter had been discussed previously between ourselves, this being in July last, and we have a test still running with one of these bearings having a pre-load of .005", the bearing running at 3,000 r.p.m., with a journal load of 1050-lbs. and a thrust load of 1420-lbs., Wakefield "E.P." Oil being the lubricant. The maximum temperature rise is 104°F.{Mr Friese}, while the normal temperature rise is 93°F.{Mr Friese}, atmospheric temperature being 70/76°F.{Mr Friese} This test has now been run for 340 hours, and no signs of distress or failure are present, thus indicating that this degree of pre-loading could be utilized without any detrimental effects upon the bearing. You will also be interested to learn that at the end of 130 hours run, this being the initial run, the pre-loading was .00225", indicating that during this period the pre-loading had slackened off to the extent of .00275", while you will be further interested to note that at the present stage when the bearing has run for a total of 340 hours, the pre-loading still remains at .00225". It seems to me that if the temperature on your job and noise are not excessive, it will be a good plan to change to .005" pre-load as the bearing apparently settles down to a certain figure of pre-loading, which as you will note from the above figures, is in excess of your present pre-loading with the job new, or, alternatively, we might strike the mean and supply the bearings with a pre-loading of .003", which would still mean that after extended running a pre-load equal to your present new bearings would still be found. I shall be glad to have your consideration of this matter, and to take any steps such as you may feel desirable. Yours sincerely, F.O. Theckle ENCLOS: E.P. Oil tests. (10). u.s.c. I/MDJT.1.1/4" brg. | ||