Letter from Hoffmann Manufacturing regarding a failure analysis of a bearing.
| Identifier | ExFiles\Box 159\7\ scan0222 | |
| Date | 18th March 1939 | |
| HOFFMANN Registered Trade Mark AGENCIES: LONDON, BIRMINGHAM, MANCHESTER, LEEDS, GLASGOW AGENTS IN PRINCIPAL COUNTRIES THROUGHOUT THE WORLD TELEPHONE: 3151 (5 lines) TELEGRAMS: HOFFMANN. CHELMSFORD CODES USED: A.B.C. 5TH EDITION. BENTLEY PHRASE, BENTLEY 2ND PHRASE. MARCONI AND WESTERN UNION 5 LETTER. THE HOFFMANN MANUFACTURING Co. LTD. BALL AND ROLLER BEARINGS STEEL BALLS AND ROLLERS CONTRACTORS TO THE ADMIRALTY, WAR OFFICE AND INDIAProduction 20 HP. with 4-speed box and Front Wheel Brakes OFFICE. CHELMSFORD. 1375 March 18th. 1939. MESSRS. ROLLS ROYCE LTD., DERBY. YOUR REF. Rm {William Robotham - Chief Engineer} /Gry. {Shadwell Grylls} 4/MH. {M. Huckerby} IN YOUR REPLY PLEASE QUOTE OUR REF. CHS/AMB. Dear Sirs, FOR THE ATTENTION OF MR. GRYLLS. We have carefully examined the Hoffmann bearing No. 340 which you returned to us as per your letter of the 13th. instant, and find that the tracks of both inner and outer races, as well as the balls, have failed. In addition, the cage is badly worn. The track of the outer race shows a suggestion of distortion, which agrees with the markings on the periphery, but in our opinion the chief cause of the failure is overload due to contraction of the outer race owing to its having fitted too tightly in the hub. This is confirmed by the creep of the inner race and the fact that the bearing has continued in service subsequent to the failure without any extension of the breakdown. As you know, with a "O" fit bearing very little interference of either the inner or outer race on its seating is sufficient to eliminate the diametric clearance, and we should be interested to learn the actual dimensions of the hub in which this bearing has been mounted. Yours faithfully, THE HOFFMANN MANUFACTURING CO. LTD. C. M. {Mr Moon / Mr Moore} Smith TECHNICAL MANAGER. | ||
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).