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 The Hoffmann Manufacturing Co. Ltd. regarding the inspection and correction of bearings with mixed ball sizes.
| Identifier | ExFiles\Box 9\7\ 07-page168 | |
| Date | 3rd May 1938 | |
| THE HOFFMANN MANUFACTURING CO., LTD. To MESSRS. ROLLS ROYCE.LTD., Page 2 Date 3.5.38. We sent six bearings to you on the 29th. ultimo which had been carefully checked by the writer for both dimensional adjustment and frictional resistance which was within your specified limits of 4 to 8 ozs at 3" radius. After you have had an opportunity of inspecting these, we look forward to receiving your confirmation that they meet your requirements. Whilst writing we should like to refer to the last paragraph of your letter of April the 12th. reference Roy{Sir Henry Royce}/DN 10/ME regarding the return of three N2790 for alteration, one of which was stated to have incorrect preload. We have carefully checked these three bearings and found that none of them was satisfactory due to the balls in them being of mixed sizes. After re-fitting with the correct size of ball both the adjustment and frictional resistance of all three bearings is satisfactory, and we will see that they are returned to you after carrying out the necessary modification to the periphery. Regarding the mixing of the balls, you are no doubt aware that to obtain the required adjustment, it is necessary to take advantage of the variation obtainable from a small range of ball sizes, and for this reason it is very important that the balls in these bearings are not interchanged. These particular bearings are, of course, held together by means of spring clips so that if the bearings are correctly assembled in the first place, mixing of the balls could only occur if the bearings were for any reason purposely taken apart. We do not think the mixing has occurred here but it is, of course, impossible to be certain of this from an examination of the parts, and if it has been due to an error on our part, we can only ask you to accept our sincere apologies. Yours faithfully, THE HOFFMANN MANUFACTURING CO.,LTD., John Wilson Research Department. | ||