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).
Visit to Ferodo Ltd. in Chapel to investigate clutch judder issues.
| Identifier | ExFiles\Box 129\4\ scan0202 | |
| Date | 21th April 1938 | |
| 1/110 To Hs.{Lord Ernest Hives - Chair} from Rm{William Robotham - Chief Engineer}/NRC.{N. R. Chandler} c. By.{R.W. Bailey - Chief Engineer} c. Da.{Bernard Day - Chassis Design} c. Mx.{John H Maddocks - Chief Proving Officer} Rm{William Robotham - Chief Engineer}/NRC.{N. R. Chandler}4/MH.{M. Huckerby}21.4.38. CLUTCH FACING. VISIT TO FERODO LTD., CHAPEL, 14.4.38. Reason for visit. We have frequently observed that the smoothness, or freedom from judder of a clutch, is likely to deteriorate after a period of use, and that the majority of facing materials we have tried are good or fairly good when quite new, but in the majority of cases deterioration is liable to occur in anything from 50 to 10,000 miles of ordinary use, and this, broadly speaking, appears to apply to all types of facing whether woven or die-pressed and with or without bonding wire. We have never found a satisfactory explanation for this evident change in the nature of the frictional properties of the material, and the following is a good actual example of the trouble. In July 1937 we fitted a new Thermoid faced plate to B.56.BN{W.O. Bentley / Mr Barrington} and it remained a quite good clutch till very recently, when at 11,700 miles it developed a judder. On dismantling for examination, there was very little difference in the appearance of the facings and new ones, the amount of wear was negligible, (certainly not more than a few thous,), but we found one of the three clutch fingers .015 out of adjustment, and thinking this might account for the trouble, we corrected it and re-assembled with the same plate, but after about 50 miles on the road, the judder returned as before. We therefore fitted a new Thermoid faced plate, of appearance almost identical to the one removed, and without making any other alteration or adjustment, and the clutch was a good one after extensive testing, thus confirming that some change had taken place in the nature of the facing removed. We therefore suggested to Ferodo Ltd. that they might like to examine this plate, in comparison with a new one, and Mr. Longley said they would be very interested to do so, I therefore went to Chapel with this plate known to be a "judderer", and a new one. | ||