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 regarding the failure analysis of a broken ball bearing and proposed modifications to drawings for a 25/30 HP Chassis steering system.
| Identifier | ExFiles\Box 106\3\ scan0377 | |
| Date | 22th May 1936 | |
| COPY OF LETTER RECEIVED FROM:- THE HOFFMANN MANUFACTURING CO.LTD., CHELMSFORD. 22nd.May 1936. Messrs.Rolls-Royce Ltd., Derby. BY/Mtn4/N MC/ELK. DO.92061.A. Dear Sirs, re: 25/30 HP. Chassis - Steering. We have to thank you for your letter dated the 20th.inst. and following our telephone conversation of yesterday were able to collect the broken 1/4" Ball which reached Chelmsford late in the afternoon. An examination of the surface of the Ball suggests that it has been rather heavily loaded. On the fracture itself however there is an indication of a slight seam in the material, and as we feel that this also must have been a contributory cause of failure, we wish to express regret that this particular Ball should have been sent to you. With regard to the alteration shewn on your drawings F.87682 and F.87683, the reduction in the track curvature from plus 50% to plus 4% as compared with the radius of the Ball will give an appreciable increase in load carrying capacity with, of course, beneficial results. We notice also that the contact angle has been only slightly reduced ( from approximately 43° to 37°), and are therefore able to express approval of the proposed modifications. We hope the further results obtained will be to your entire satisfaction, and beg to remain, Yours faithfully, THE HOFFMANN MANUFACTURING CO.Ltd., (Sgd) M.J.Cooper. Research Engineer, | ||