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).
Experiments on Phantom III clutches, comparing various plate designs and materials.
| Identifier | ExFiles\Box 129\3\ scan0017 | |
| Date | 1st January 1936 | |
| To E & By.{R.W. Bailey - Chief Engineer} c. to WCr. c. to Mx.{John H Maddocks - Chief Proving Officer} K110 Hs{Lord Ernest Hives - Chair}/Smth.2/EW.S.1.36. Phantom III Clutches. We have been proceeding with experiments on Ph.III clutch jagger. The most satisfactory centre plate we have had up to date is a 12" Long plate brough back from America. This is of the 'compound cushion' type; i.e., one fabric is mounted directly on the flat segmented driven plate and the other is mounted on spring strips which are in turn riveted to the driven plate. The advantage of this type of construction is that both fabrics are kept flat during all stages of the take up. The linings are of "Lyco", a brass bonded woven fabric manufactured by Raybestos. One of the reasons for the success of this plate may be that owing to the small diameter, the working /u is .23" as against .19" on the standard clutch. Borg & Becks are taking over the Long interests in this country, and are looking into the question of making us a standard size Ph.III plate with Long construction and Lyco linings. Meanwhile, we are about to try weaker clutch springs in the SpectreCodename for Phantom III. We have some to give a /u of .21", and others to give .23". We are of the opinion that the greater the power weight ratio of a car, the higher can be the working /u. We are of course anxious that the springs should be no stronger than is necessary, for ease of operation as well as smooth take up. The Long clutches on the Packard and Lincoln cars use a working /u of .25". We have been experimenting with some Borg & Beck plates. The theoretical separation of the Ph.III clutch is .092" for a pedal travel of 5.000". We find the actual separation to be .085". This is sufficient for a cushioned plate with quite a lot of crimping, without increasing the pressure plate travel. | ||