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 Hoffmann Manufacturing Co. Ltd. discussing specifications for a special outer race and needle rollers.
| Identifier | ExFiles\Box 9\7\ 07-page131 | |
| Date | 25th January 1938 | |
| BRANCHES: LONDON, BIRMINGHAM, MANCHESTER, LEEDS, GLASGOW. AGENTS IN PRINCIPAL COUNTRIES THROUGHOUT THE WORLD. HOFFMANN Registered Trade Mark BALL AND ROLLER BEARINGS STEEL BALLS AND ROLLERS THE HOFFMANN MANUFACTURING Co., LTD. CONTRACTORS TO THE ADMIRALTY, WAR OFFICE AND INDIA OFFICE. TELEPHONE: 3151 (Five Lines) TELEGRAMS: HOFFMANN, CHELMSFORD CODES USED: A.B.C. 5TH EDITION, BENTLEY PHRASE, MARCONI AND WESTERN UNION 5 LETTER. MESSRS. ROLLS-ROYCE, LTD., DERBY. CHELMSFORD. 25th January, 1938 YOUR REF. Rm{William Robotham - Chief Engineer}/PJH. 9/JH. IN YOUR REPLY PLEASE QUOTE OUR REF. JHW/PS. 103913. Dear Sirs, We thank you for your letter of the 22nd January and copies of drawing Nos. GW.1961, GW.1962 and PD.97 which have had our close attention. We have pleasure in enclosing a copy of drawing No. 43-579E illustrating the special outer race and needle rollers we shall supply and our drawing gives the diameter to which the inner track should be made. The outer race should be kept with the rollers inset as supplied. We would recommend that the .035" minimum depth of case should be maintained after finish grinding and that the hardness of the track should be HD.{Mr Hayward/Mr Huddy}800 or C63 Rockwell. The outer race and rollers shown on our drawing have ample capacity for dealing with the normal load but they will be loaded to the limit of their capacity with a load of 6,000 lbs and to avoid the possibility of indentation of the tracks it will be important to ensure that the pin is correctly hardened. We gather it is intended to take the weight on the face of the outer race so that rubbing will occur between the thrust flange and the race and this is a practice we do not normally recommend although it is possible it will be satisfactory provided the surfaces can be kept lubricated. We assume you are satisfied that the very small shoulder on the outer race will be sufficient to transmit the weight to the housing. The protection afforded by the felt pad at the top is not quite as efficient as we would like to see for the dirty and wet conditions which are generally involved in this application but we gather that the parts cannot be altered to form a more efficient seal. To ensure good results with needle roller bearings it is important that the tracks should be truly parallel and the slackness in the top plain bearing should be kept as small as possible to avoid mal-alignment. If at a later date you find it possible to Handwritten notes: Top of page: 650 Left margin: OK guarantee 800 Brinell *This is an error on their part, they will clear up are using needle roller(B7) | ||