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).
Letter discussing the use of 'Tenoid' material and comparing Silver Ghost and Phantom clutches.
| Identifier | ExFiles\Box 74\2\ scan0225 | |
| Date | 18th March 1929 | |
| C O P Y. BY11/G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 18th. March 1929. Mr. M.{Mr Moon / Mr Moore} Olley, Messrs. Rolls-Royce of America, Inc. Springfield, Mass. Dear Mr. Olley, CLUTCH - SECTION 6000. Referring to your letter of the 1st. inst. (ref. OY.7) we certainly should not recommend the use of 'Tenoid' material in place of 'Ferodo' for the clutch. Even for use on the brakes we are still in doubt as to whether it is as good as 'Ferodo'. In regard to the question of squeaking, further experience shows that very little advantage, if any, is gained by the use of 'Tenoid', and judging by durability we consider it is not so good as 'Ferodo'. The difference is such that we would not recommend it for use at all on the 20 HP. brakes, and we only used the 25% of our requirements on the 40/50 HP. brakes to check whether its apparent non-squeaking qualities are permanent - we should now say they are not, and we will most probably abandon its use. With reference to the comparison of the Silver Ghost and Phantom clutches, it is very evident that in the States a considerable amount of clutch slipping is resorted to under certain circumstances, this being so, the old Silver Ghost cone clutch with its cotton fabric facing fitting into a cone external to its cone had two distinct advantages :- The heat generated by 'slipping' could not rapidly heat up the slipping surfaces as the rim of the flywheel had to be raised in temperature, as you will of course appreciate it, before any change to the fabric could take place, whereas in the case of the Phantom clutch the light steel member has very little capacity for heat, and therefore its temperature rapidly rises under the friction effects set up when the clutch is 'slipped'. Further the only way in which the thin steel driven member of the clutch can dissipate its heat is inwards towards the coupling, and this only at a very slight rate, consequently if clutch slipping is resorted to regularly trouble must undoubtedly ensue. | ||