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 Ferodo Limited discussing test results and performance characteristics of metallic (RAD.5) versus non-metallic (RAD.13) clutch discs.
| Identifier | ExFiles\Box 85\2\ scan0060 | |
| Date | 5th January 1934 | |
| All Communications to be addressed to the Company. FERODO LIMITED TELEPHONE: 19 CHAPEL-EN-LE-FRITH (4 LINES) TELEGRAMS: FRICTION, PHONE, CHAPEL-EN-LE-FRITH. FERODO REGD TRADE MARK BRAKE & CLUTCH LININGS CODES: WESTERN UNION FIVE LETTER EDITION, BENTLEYS COMPLETE & 2ND PHRASE, MARCONI INTERNATIONAL, LIEBER'S CODE, LIEBER'S LATEST CODE, A.B.C. 5TH & 6TH EDITIONS. CHAPEL-EN-LE-FRITH, VIA STOCKPORT, ENGLAND. Depots:- LONDON 222, TOTTENHAM COURT RD W. 1. ABERDEEN 96, GUILD STREET. BELFAST 8, 10 & 12, MONTGOMERY ST BIRMINGHAM 202, CORPORATION ST BRIGHTON QUEEN'S ROAD. BRISTOL 19, PARK STREET. CARDIFF 39, CHARLES ST DUBLIN 120, UPPER ABBEY ST GLASGOW 70, WATERLOO ST LEEDS 25, HUNSLET RD LIVERPOOL 1-3, BERRY STREET. MANCHESTER 32, CATHEDRAL ST NEWCASTLE-ON-TYNE WORSWICK CHAMBERS, OFF PILGRIM ST [Handwritten annotations] GAX ** x212 January 5th 1934 YOUR REF. OUR REF. FJF/WAC. Messrs. Rolls-Royce Ltd., Derby. For the attention of Mr. Grylls. We thank you for your letter of the 2nd instant and may say that since the visit of your Mr. Grylls in connection with the behaviour of a pair of clutch discs taken from a Bentley car, we have conducted a series of very careful tests with a number of RAD.5 and RAD.13 discs, in order to establish a definite comparison between them in respect to resistance against wear and temperature - with the result that after prolonged applications we find the advantage is in favour of the metallic disc RAD.5 over the non-metallic RAD.13 in the order of approximately 3 : 1. In the tests in question the duty was particularly severe, accompanied by elevated temperatures, using a centre steel plate slotted radially and not too carefully chamfered. So far as friction is concerned, both types exhibited practically similar characteristics; with new surfaces μ was of the order of 0.5 settling down to a steady value of μ = 0.4. We are sending under separate cover six RAD. 5 discs and if you will try them out we think you will find them more satisfactory than any other type available at the present time. Referring to absorption of oil, generally speaking all woven fabric materials are absorbent to a certain extent and naturally the presence of lubricant, whether on or underlying the surface, must affect the coefficient of friction and it is our experience that when oil is present, even with material that is non-absorbent, the same loss of holding power obtains as in the case of material that is slightly oil-absorbent. Apart from this characteristic RAD.5 is not affected by oil and is supplied in very large quantities for working in oil, particularly in connection with the cone clutches in Wilson gearboxes. Yours faithfully, FERODO LIMITED. [Signature] CHIEF ENGINEER. | ||