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 tolerances and clearances for steering rollers.
| Identifier | ExFiles\Box 153\1\ scan0188 | |
| Date | 31th January 1939 | |
| 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, BENTLEY 2ND PHRASE MARCONI AND WESTERN UNION 5 LETTER CHELMSFORD. January 31st. 1939. YOUR REF. Da{Bernard Day - Chassis Design}/DB.{Donald Bastow - Suspensions}1/N. IN YOUR REPLY PLEASE QUOTE OUR REF. CHS/AMB. DO.110400 MESSRS. ROLLS ROYCE LTD., DERBY. Dear Sirs, FOR THE ATTENTION OF MR. F.J. HARDY. In reply to your letter of the 18th. instant, we agree that if the tolerance for the protrusion of the inner races beyond the faces of the outer race were the result of all the internal tolerances governing the tracks, the limits would be much wider than +.0015 to -.0005", as specified on your drawing No. F.89828. It has, however, been our practice with similar steering rollers to assemble selectively in order to maintain a tolerance on this dimension of .002", and we propose, therefore, to retain the limits given on your drawing. With regard to the circumferential clearance, we have found by experience that if this is not sufficient in angular contact bearings without cage, there is a tendency for the balls to crowd and cause friction. The amount of clearance necessary to avoid this depends, of course, on the size of the bearing and the number of balls, but within the range of these steering rollers, .0035" to .005" per ball should be quite satisfactory and is what we should usually work to. Yours faithfully, THE HOFFMANN MANUFACTURING CO. LTD. C.H. Smith TECHNICAL MANAGER. [Handwritten notes:] [Top middle:] 1300 [Top left:] Pa{Mr Paterson} D/B Please Note & return FJH{Fred J. Hardy - Chief Dev. Engineer} [Center, stamped:] FJH{Fred J. Hardy - Chief Dev. Engineer} [Right side, handwritten:] FJH{Fred J. Hardy - Chief Dev. Engineer} | ||