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).
Herman Cron clutch issues, including grooving, thermoid qualities, and spring modifications.
| Identifier | ExFiles\Box 146\1\ scan0265 | |
| Date | 1st June 1938 | |
| 1245. W/P - Sr. c. to Hd.{Mr Hayward/Mr Huddy} c. to By.{R.W. Bailey - Chief Engineer} c. to Mx.{John H Maddocks - Chief Proving Officer} Rm{William Robotham - Chief Engineer}/NRC.{N. R. Chandler}14/JH.1.6.38. 3.CP.88 Herman Cron - Clutch In reply to Sr/VA.5/ET.23.5.38. we have observed several cases in which the flywheel and pressure plate have been lightly grooved by Thermoid, but we have not seen one in which the grooving has been of measureable depth, actually, on a polished surface, the depth of the grooving is very deceptive, and on measuring it with a clock, it will usually be found to be a fraction of .001. We have not found any ill effect from the apparent grooving, and have recently effected several cures by fitting lighter thrust springs (supplies are on order, and we will write you shortly on this matter). The question of deterioration in the frictional qualities of the thermoid may and probably does exist, but we appear to have effected cures by fitting lighter springs even without changing the driven plate, but only time will show whether or not the cure is permanent. You were quite right in fitting the .070 packing as this reduces the effective poundage of each spring by 15 to 16 lbs. which is a good step towards the 27 lb. reduction provided by the new springs now being prepared. With regard to oil on a clutch, our experience is that it may cause temporary relief while the oil is quite fresh, the oil quickly becomes partly burnt, and results in a sticky deposit which is very bad indeed for judders. With regard to grooving, this is a well known characteristic of brake linings containing rubber, and in moderation, does not appear to have any ill effect. Rm{William Robotham - Chief Engineer}/NRC.{N. R. Chandler} | ||