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).
Ferodo Ltd's materials for main clutches and servo clutches.
| Identifier | ExFiles\Box 26\4\ Scan275 | |
| Date | 21th September 1925 | |
| x719 HS.{Lord Ernest Hives - Chair} RHO! BY7/H.{Arthur M. Hanbury - Head Complaints} 21.9.25. FERODO LTD'S MATERIAL FOR MAIN CLUTCHES AND SERVO CLUTCHES. ------------------------------------------------------ The material delivered is of two types:- 1. Ferobestos "D". which is the last that has come to hand, and that referred to in our memo of this morning, BY2/H.{Arthur M. Hanbury - Head Complaints} 21.9.25. This material is not woven at all. it is a material made up from asbestos, finished by pressing together with cement of some description, probably synthetic resin. 2. Ferobestos "SW". which we supplied to you earlier than the samples above referred to, and in this case the material is woven and intermixed with wire, it being very similar so far as weaving is concerned, to the Ferodo, but it is of a different colour, and may be of a different cementing material. The advantages of this material are that it is supposed to be non-squeaking and is supposed not to drop its coefficient of friction in a similar manner to that which we objected to in the case of Ferbestos "D", when we used it for main clutches and brake shoes as an experiment. In regard to the non-squeaking material for/road brakes, this has come to hand this morning, and is, I believe of a somewhat similar nature to Ferbestos "SW". I am personally of the opinion that if it does not squeak, it will not maintain its coefficient of friction. this is not a guess in the dark, but is based upon an idea that the material is made up with a synthetic resin, that the burning of the resin provides lubrication, which prevents squeaking by reducing the friction. it is therefore important to watch this point in testing. The reason you have not got two samples of material for main clutches, whereas you have got two for servo clutches is that admittedly Ferobestos "D" looses its coefficient of friction as the temperature rises. this makes it useless for clutches, and I informed Ferodo Ltd. that we were not prepared to go any further with this type of material on main clutches, but since the servo clutches had nothing like the duty of the main clutch, I thought it desirable, as the "Halo" which we are using appears to be similar, to Ferobestos "D", that we might experiment with Ferobestos "D" and Ferobestos "SW". BY.{R.W. Bailey - Chief Engineer} | ||