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).
Clutch thrust spring pressures and calculations for 'Borg & Beck' and 'Long' clutches on Bentley vehicles.
Identifier | ExFiles\Box 130\3\ scan0019 | |
Date | 30th November 1938 | |
1110. To Da.{Bernard Day - Chassis Design} from Rm{William Robotham - Chief Engineer}/NRC.{N. R. Chandler} c. to By.{R.W. Bailey - Chief Engineer} c. to Hdy.{William Hardy} Rm{William Robotham - Chief Engineer}/NRC.{N. R. Chandler}1/JH.30.11.38. re Clutch Thrust Pressure 'Borg & Beck' and 'Long'. The following particulars of clutch thrust springs as actually used, will be of interest when considering problem connected with pedal mechanism etc. 10" Borg & Beck (No.C.F. assistance). After considerable experiment, the following springs have been adopted as standard for Bentley. 6 Black springs, nominally 165 lbs. 3 Green " 110 lbs. Actually the thrust is in excess of this figure because the working length of the springs averages about .110 less than the nominal length of 1.687, when clutch is engaged. The rate of the black spring is 220 and the green spring is 110 lbs. per inch, so that the actual thrust poundage is - 6 Black springs 165 + (220 x .110) = 189 x 6 = 1134 lbs. 3 Green " 110 + (110 x .110) = 122 x 3 = 366 " ----- 1500 " Less approx. 120 lbs. for anti-rattle springs 120 " ----- 1380 lbs. engaged Owing to the rate of the thrust springs, the total thrust when clutch is withdrawn, assuming .060 separation is approx, 1480 lbs., and since the finger lever ratio is 5.5 to 1, the max. pressure on the withdrawal thrust bearing is approx. 269 lbs. | ||