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 supplier discussing specifications for steering roller bearings, including diameters and contact angles.
| Identifier | ExFiles\Box 153\1\ scan0099 | |
| Date | 23th November 1937 | |
| 1300 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. November 23rd. 1937. MESSRS. ROLLS ROYCE LTD., DERBY. YOUR REF. Rm{William Robotham - Chief Engineer}/FJH.{Fred J. Hardy - Chief Dev. Engineer}10/AP. IN YOUR REPLY PLEASE QUOTE OUR REF. CHS/AMB.102727 FOR THE ATTENTION OF MR. F.J. HARDY. Dear Sirs, In reply to your letter of the 17th. instant with reference to steering rollers, we would say that we are grinding the tracks of the inner races to suit individual outer races, so that we do not make these to any definite limit. They will, however, be increased to the following diameters:- Hoffmann Bearing No. Your Part No. Diameter. N.2784 F.61471 .7305" N.2891 F.89447 .9085" N.2904 F.89670 } .7692" N.2790 FW.911 } In the case of bearing No. N.2790, the latter dimension refers only to future orders. We cannot trace any information from yours regarding a contact angle of 45° which you now mention, and with the limits of track diameter and curvature given on your drawings, the angle can vary considerably. For instance, in bearing No. N.2784 it may be anything from 24° to 82°. This tolerance is obviously too wide to obtain comparable results as regards free running, and with our selective assembly is considerably reduced. In the aforementioned bearing, we aim at a mean angle of contact of 42° in the unloaded condition, compared with a mean of 53° obtainable from your drawing. The angle of contact will, of course, increase according to the thrust load applied. | ||