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).
Clutch issues, discussing torsion springs, friction tests, and interactions with supplier Borg & Beck.
| Identifier | ExFiles\Box 130\3\ scan0165 | |
| Date | 31th January 1941 | |
| The reason for having three samples is that Borg & Beck are not able to say what spacer length and what shims are required for any set quantity of friction. Note:- The tolerance on the length of the spools is .003". The riveted length depends on some extent on the way the girl handles the machine. R.{Sir Henry Royce} Varying interference between the torsion springs and the retaining wires. The reason for this is not clear since the springs press against only one of the pair of wires which pass through them. Borg & Beck said that the Marlesone had tried Lico on the outer plates in place of retaining wires. The War appeared to be a minor catastrophe compared with changes to B.A. B.'s plate size and they offered no help in overcoming this interference. We will try and find a cure. Torsional Friction and rate tests on clutch discs. Borg & Beck stated that stronger torsion springs reduced the friction in a clutch disc, because the stronger springs overcame more of the friction. As this appears to be most illogical, some enquiries were made about their friction tests. Their test differs from ours in the following respects:- 1. No balance weight is used, so they are not able to test right through the no torque position. 2. Torque is applied by hanging weights on an arm. This is bad because of the difficulty of preventing the momentum of the weight causing an apparent reduction in friction. This method was not successful at Vauxhall, although B.A B. said they obtained good results. 3. Deflection is measured at the end of the arm to which the load is applied, so that arm deflection is included with clutch deflection. General attitude of Borg & Beck to our problem. This may be summarised as follows:- 1. One cannot expect consistency from a mass produced article and their clutch was a mass produced article. 2. One expects a car to rattle after 25,000 miles. There is therefore no necessity to make clutch friction remain constant for this mileage. R/VG | ||