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).
Minutes of a conference regarding the Borg & Beck clutch springs for the 4 1/4 litre Bentley.
| Identifier | ExFiles\Box 129\4\ scan0055 | |
| Date | 8th November 1937 | |
| To Hs.{Lord Ernest Hives - Chair} from Rm{William Robotham - Chief Engineer}/NRC.{N. R. Chandler} c. By.{R.W. Bailey - Chief Engineer} c. Borg & Beck Ltd. Rm{William Robotham - Chief Engineer}/NRC.{N. R. Chandler}7/MH.{M. Huckerby}8.11.37. 10" Borg & Beck Clutch, 4 1/4 litre Bentley. Conference held at Derby, Oct. 29th. As a result of correspondence with Messrs. Borg & Beck re the poundage of the thrust springs of Bentley clutches, Messrs. Armitage and Barker offered to visit Derby to discuss the matter with us, and a conference was held on Oct. 29th. Present. Messrs. Armitage and Barker of Borg & Beck. " Thompson and Young of The Tempered Spring Co., Sheffield. " Robotham and Chandler. As a preliminary, it was explained that in order to overcome complaints of clutch jaggers on certain customer's cars, it was considered desirable to replace the driven plate by one fitted with "Thermoid" facings. Experience showed that Thermoid has a slightly lower "mu" than the original asbestos, and that if the thrust springs have a mean poundage appreciably below 150, excessive slipping is likely to occur in the hands of a certain type of driver who habitually slips his clutch, although in the hands of a good driver damage to the clutch is not anticipated, but it must be recognized that the bad driver exists and must be catered for. It is found that many of the clutches in service have springs considerably below 150 lbs., many tested being under 140 lbs., and in a few cases under 130 lbs., and it would therefore be unwise to fit Thermoid faced plates without first insuring that the thrust springs are up to 150 lbs. Mr. Thompson stated that it is an established fact that springs which are permanently stressed in the neighbourhood of 90,000 lbs. will | ||