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 manufacturer regarding the axial deflection and end movement of a ball journal bearing under various loads.
| Identifier | ExFiles\Box 114\1\ scan0208 | |
| Date | 2nd June 1939 | |
| 1018 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, AIR MINISTRY AND INDIA OFFICE. TELEPHONE: 3151 (FIVE LINES) TELEGRAMS: HOFFMANN, CHELMSFORD CODES USED: A.B.C. 5TH EDITION, BENTLEY PHRASE, BENTLEY'S 2ND PHRASE, MARCONI AND WESTERN UNION & LETTER CHELMSFORD. GRY{Shadwell Grylls} MESSRS. ROLLS ROYCE LTD., DERBY. June 2nd. 1939. YOUR REF. Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls}5/MH.{M. Huckerby} IN YOUR REPLY PLEASE QUOTE OUR REF. CHS/AMB. 112727A Holt please return Dear Sirs, FOR THE ATTENTION OF MR. GRYLLS. Further to your letter of the 12th. ult. and the query you raised regarding the axial deflection of a ball journal bearing. With this type of bearing, owing to the shape of the running tracks and rolling elements, a certain amount of thrust load is always necessary to cause one race to move endways in relation to the other. Taking the size of bearing you mention, viz., No. 340, we have calculated the amount of end movement from the central position, which will occur under a total load of 1000 lbs. with varying percentages of thrust and journal. This is shown by the full lines on our drawing No. 58-1009, a print of which is enclosed. If the thrust acts alternately in both directions, the amount of end movement given on the curve must be doubled. As you will see from the curve, the effect of small alterations in the curvature of the running tracks is considerable, particularly when the percentage of journal load is small. The end movement will be also affected by any variation in the diametric clearance, so that it is difficult to give figures which will cover every case. The drawing also shows the axial deflection caused by pure thrust without any journal load from Zero up to 1000 lbs., and it is interesting to note that journal load below about 25% has practically no effect on the end movement. We regret the delay in answering your letter, but | ||