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).
Modifications and comparisons for a 25-30 HP clutch.
| Identifier | ExFiles\Box 103\1\ scan0193 | |
| Date | 13th January 1936 | |
| x512 BY.{R.W. Bailey - Chief Engineer} c.c. E.Hs.{Lord Ernest Hives - Chair}Da.{Bernard Day - Chassis Design} RMO. Hs{Lord Ernest Hives - Chair}/Nm. E/HDY.{William Hardy}2/HP.13.1.36. Clutch - 25-30 HP. We send herewith N.Sch.4731 which shows the levers and adjustment link for use with the R.R.clutch on this car. We are sending later particulars of two pressure plate springs, in the one case with an increase of load over the present standard spring proportional to the increase of torque, and in the other case with an increase half way between the standard and proportional loads. The leverage of operation now suggested will give the same pedal loads as on the standard 20/25 with the weaker of the above springs. The pressure plate separation is reduced from .106 to .096 which is still more than is obtained on the R.R. Bentley clutch .088 and the Borg and Beck Bentley clutch .095. The coefficient of friction necessary with the weaker spring is .198 and with the stronger .181, as on the standard 20/25. These figures are exceeded on various clutches (Bentley R.R. Borg and Beck) but we have to pay some regard to the fact that slipping is a serious complaint on the standard 20/25 clutch, so that unless compensating alterations are made it would not appear to be wise to rely on a much higher coefficient than is now used. E/HDY.{William Hardy} | ||