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).
Examining the construction and damping capabilities of a Borg & Beck clutch centre.
| Identifier | ExFiles\Box 130\3\ scan0159 | |
| Date | 16th January 1941 | |
| To Rm.{William Robotham - Chief Engineer} from Rm{William Robotham - Chief Engineer}/GB. Copy to Rm{William Robotham - Chief Engineer}/Wym.{G. Harold Whyman - Experimental Manager} Rm{William Robotham - Chief Engineer}/FJH.{Fred J. Hardy - Chief Dev. Engineer} CLUTCH CENTRE DAMPING. This memo is in reply to Rm.{William Robotham - Chief Engineer}10/ML.4.1.41, which asked two questions:- 1. Whether the construction of the Borg & Beck clutch centre is sufficiently good to permit of accurate damping being obtained. 2. How long the damping is likely to last. An examination of the clutch disc from Lp.{Mr Lappin}'s car has shown very clearly that the construction is not good enough to obtain accurate damping. The reasons for this, together with notes on construction, appear below. The clutch disc assembly consists of a hub with a flange which is permitted to have a total rotational movement of 8° between two discs which are fixed to each other by four collars with integral ends riveted over. Disc A.{Mr Adams} (see sketch) carries the friction linings. Between disc B. and the hub flange is a shim. Nip between the discs is the means of providing hub damping. Spring in disc B. should enable damping between the discs and hub flange to be kept fairly constant without going to very close limits on the length of the riveted collars. Unfortunately there is often heavy direct pressure between disc B. and the hub flange close to the riveted collars. It is practically impossible to have any control over damping obtained here. The radius at which all pressure between disc A.{Mr Adams} and the hub flange may be said to be concentrated is not fixed well enough. Another source of damping is pressure between the torsional springs and their retaining wires. In one new disc (N°1 in Rm{William Robotham - Chief Engineer}/GB.9/ET.30.12.40) removal of the retaining wires reduced the depth of the friction loop from 45 to 55 lb/ft. to a uniform 36 lb/ft. In a second disc (N°4 in the above memo) removal of the retaining wires had no effect on the depth of the friction loop. | ||