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 concerning belt angles, friction coefficients, and test results for expanding and contracting pulleys.
| Identifier | ExFiles\Box 135\4\ scan0026 | |
| Date | 22th May 1939 | |
| 1135 All Communications to be addressed to the Company FERODO LIMITED BRAKE & CLUTCH LININGS CHAPEL-EN-LE-FRITH, STOCKPORT, ENGLAND. TELEPHONE: 250 CHAPEL-EN-LE-FRITH TELEGRAMS: FRICTION, PHONE, CHAPEL-EN-LE-FRITH. 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. Depots - LONDON 222, TOTTENHAM COURT RD W. 1. ABERDEEN 26, GUILD STREET. BELFAST 8 & 12, MONTGOMERY ST BIRMINGHAM 198, CORPORATION ST BRISTOL 118, VICTORIA STREET. CARDIFF 60, CHARLES ST DUBLIN 120, UPPER ABBEY ST GLASGOW 70, WATERLOO ST LEEDS 25, HUNSLET RD LIVERPOOL 1-3, BERRY STREET. MANCHESTER 18, JACKSON'S ROW, DEANSGATE. NEWCASTLE-ON-TYNE 24, ELDON PLACE, BARRAS BRIDGE. [Handwritten in red ink, struck through] HARNDALE [Handwritten in red ink] EDWARDS See me 22nd May, 1939 YOUR REF. RM{William Robotham - Chief Engineer}/FWK.6/MH.{M. Huckerby} YOUR REF. RM{William Robotham - Chief Engineer}/Ed.{J. L. Edwards}12/JH OUR REF. WES/PW. Messrs. Rolls-Royce Ltd., Derby. For the attention of W.A. Robotham, Esq. [Handwritten in pencil] file 1305 Dear Sirs, We thank you for your reply, reference RM{William Robotham - Chief Engineer}/FWK.6/MH{M. Huckerby}, to ours of the 22nd April with regard to spring interleaving, and look forward to hearing from you after Messrs. Toledo Woodhead's test rig has been running. With regard to your letters of the 12th and 17th instant respectively with reference to the belt angle most suitable for expanding and contracting pulleys, there appears to be very little data available for high speed drives. We realise the attractiveness of a narrower angle belt but the minimum angle appears to be definitely connected with the coefficient of friction between the belt and the [word 'cover' is struck through and 'PULLEY' is handwritten above] pulley if a reasonable force is to be employed for contracting the pulley and therefore increasing the pitch circle at which the belt runs. We have attempted to measure the coefficient of friction between a belt cover and polished cast iron or steel and find that the apparent coefficient of friction is as low as .45 at low percent slip, rising to values between .5 and .6 with increasing slip. In view of the relatively high µ which is obtained between the belt and pulley we consider that the belt angle should not be reduced below the present 42° for Ferogrip V.164 belt as run on our test rig here. We consider that quite a number of other points arise in connection with such a drive, and the best way of investigating this is for the writer to interview you. Perhaps you will be good enough to give us a convenient date and time for such an interview. Yours faithfully, FERODO LIMITED. W. E.{Mr Elliott - Chief Engineer} Shilton Manager, Technical Department. [Handwritten in pencil in bottom left corner] Belts to EB 4202. Alum pulleys. | ||