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).
Three methods to reduce clutch pedal pressure on the 25HP and J.3 clutches.
| Identifier | ExFiles\Box 103\1\ scan0025 | |
| Date | 5th April 1933 | |
| HS{Lord Ernest Hives - Chair}/RM.{William Robotham - Chief Engineer} FROM DA.{Bernard Day - Chassis Design} 18300 DA{Bernard Day - Chassis Design}1/M5.4.33. C. to SC. WOR.{Arthur Wormald - General Works Manager} BY E.{Mr Elliott - Chief Engineer} CLUTCH PEDAL PRESSURE. Referring to our conversation over the telephone yesterday as to reducing the pedal pressure on the 25HP. and J.{Mr Johnson W.M.} 3 clutches, there are 3 ways in which this could be done assuming a given engine torque and a single plate clutch: (1) By increasing the dia. of the clutch plate. (2) By increasing the travel of the pedal plate. (3) By reducing the travel of the pressure plate. No. 1. is rather difficult to do without considerable alterations to existing parts, and is also undesirable because of increased inertia affecting the synchro mesh change. With reference to no. 2. this can be done to a small extent, and whether we should do so or not largely depends on whether the increased movement of the pedal is comfortable from the driver's point of view. We have the impression that to have to move the pedal a long distance always is not a good feature. [Handwritten note: Contrl Drg] Referring to No. 3. we sent you on 13.10.32. a drawing - N. sch. 3564 - shewing how the travel of the pressure plate could be reduced from approx: .125 (theoretical) to .09 (theoretical), thus affecting a saving of approx: 28% in the pedal pressure. We believe that this clutch has never been tried though it has several additional desirable features, namely, a sprung back plate which is said to reduce flywheel vibration, cast iron surfaces, and increased friction surfaces, which together are said to much reduce the wear and simplify construction, which should reduce the initial cost. In this same letter - viz.DAL/M131032. - we pointed out that we considered we had sent you enough information to enable the features of increased friction surfaces, and cast iron surfaces, and simpler construction, to be applied to all the clutches, namely, Peregrine, 25HP., J.{Mr Johnson W.M.} 3., and P. 2. Of Peregrine, 25HP., and P. 2. we have sent you drawings, and since the Peregrine clutch was originally scaled down from J.{Mr Johnson W.M.} 3. clutch a modified J.{Mr Johnson W.M.} 3. clutch would be obtained in the same way by scaling up from the revised Peregrine. We suggest that the improvement gained by reducing the travel of the pressure plate should be tried, and that if the reduction in pressure is still insufficient we then might consider increasing the travel of the pedal. DA.{Bernard Day - Chassis Design} | ||