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).
Depot sheet request detailing inspection methods for jaggering clutches on Bentley 4 1/4 litre and 25/30 HP models.
| Identifier | ExFiles\Box 129\3\ scan0339 | |
| Date | 13th July 1936 | |
| X1110 To Hd.{Mr Hayward/Mr Huddy} (FOR DEPOT SHEET). Hs{Lord Ernest Hives - Chair}/Smth.18/KW.13.7.36. Will you please issue a Depot Sheet regarding the method of inspection of Bentley 4 1/4 litre and 25/30 HP. clutches which are jaggering. The two principal causes of jaggering are incorrect setting of the operating fingers and irregularities in the thickness of the driven plate when it is compressed. A contributing cause in some cases is poor finish on the flywheel. Finger Setting. To check this - (1) Mount the clutch on the flywheel in the normal manner but with the driven plate replaced by a metal gauge plate of uniform thickness. (2) Work each of the fingers, say, half a dozen times and tap the eyebolt nuts to ensure that the fingers have settled into their correct working position. (3) Find the highest points of the finger contact pads by bluing them with a flat surface. (4) Find the variation in height of these points by mounting a clock gauge from the crankcase joint face and turning the flywheel, being careful to take up all the end float in crank. If the maximum variation between two of the fingers exceeds .005", the clutch should be changed. Thickness of Driven Plate. Find the thickness of the driven plate when compressed locally at the centre of each crimped segment. If there is an irregularity of more than .005", the plate should be changed. Flywheel Finish. On the earlier 4 1/4 litre Bentley and 25/30 units, the finish of the flywheel friction surface is not dead smooth. An improvement can be made by rubbing lightly with fine emery paper. | ||