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).
The investigation of clutch jagger issues in a Phantom III model.
| Identifier | ExFiles\Box 129\3\ scan0170 | |
| Date | 30th March 1936 | |
| To E.{Mr Elliott - Chief Engineer} c. to Wor.{Arthur Wormald - General Works Manager} c. to By.{R.W. Bailey - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} c. to Hdy.{William Hardy} c. to Mx.{John H Maddocks - Chief Proving Officer} c. to RHC.{R. H. Coverley - Production Engineer} X1110 Hs{Lord Ernest Hives - Chair}/Smth./KW.30.3.36. Ph.III Clutch Jaggers. We have not yet got a satisfactory clutch for Ph.III. 32-EX is now on the road with a clutch built to production specification, and occasional clutch jaggers are reported. The clutch is inconsistent, as it was perfectly smooth at the outset, but deteriorated after use on Green Bank. This feature has been common to all the Borg & Beck driven plates which we have tried. This clutch is not good enough for production. The clutch in 33-EX, which was of the old type with a thin pressure plate and had no horse-shoe slots in the driven plate (see Hs{Lord Ernest Hives - Chair}/Smth/KW.13.2.36), commenced to jagger badly after the issue of the above report. We have now stripped the clutch and find it to be in the following condition. (1) Pressure Plate. This was distorted by a maximum of .007" and showed very uneven bedding. It had been stress-released prior to final machining, so that the necessity for going to the stiffer plate is confirmed. The friction surface was not particularly well finished and had picked up slightly in certain parts. We think the finish on the Ph.III pressure plates is not good enough, and that the method of grinding should be improved. Borg & Beck are very critical of it and say that in their experience the only satisfactory way to grind flywheels and pressure plates is in such a manner as to leave concentric grinding marks. They say our finish is very likely to give rise to jaggers. (2) Driven Plate. One of the fabrics on the driven plate was cracked in several places. The clutch had been doped to prevent jaggering and had been slipping badly. The cracks were possibly due to this. (3) Oilite Bush. The oilite bush had seized on the first motion shaft and was turning in the bore of the sleeve. This is the first case we have had of this occurring. We think that this bush should be made fully floating. | ||