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 to Borg & Beck Ltd. describing a rig designed to measure thrust on clutch pressure plates and findings from tests.
| Identifier | ExFiles\Box 159\6\ scan0032 | |
| Date | 25th February 1938 | |
| 1371 also 1110 RM{William Robotham - Chief Engineer}/HAC.1/MH.{M. Huckerby} 25th. February 1938. Messrs. Borg & Beck Ltd., Tachbrook Road, Leamington Spa, WARWICKS. For the attention of Mr.Armitage. Dear Sirs, You may remember that some time ago, the writer remarked that he was preparing a design for a rig to measure the actual thrust on the pressure plate of your 10" and 11" clutches, and you said you would be interested to have particulars. We have now completed one, which consists briefly of a stepped plate representing the flywheel and driven plate, and an arrangement of knife edge mounted levers, through which a weight sliding on a beam having calibrated notches, causes three plungers to act upon the pressure plate. Clamps are arranged for holding down either the 10" or 11" clutch. Readings accurate to within 2 to 3% are easily and quickly obtained. We find that a number of the 10" clutches tested showed a higher poundage than could be accounted for by the tested strength of the thrust springs, and investigation showed this to be due to the working length of the springs being .100 to .120 less than the nominal 1-11/16, assuming .330 for the driven plate, but this extra poundage is partly cancelled out by the anti-rattle springs, the strength of which appears to vary considerably. In the case of the 11" clutch, the thrust springs are not compressed to such an extent. We checked up the effective length of the thrust springs by making three tubes of mild steel 1.125 dia. and 1.687 long mounting them in a clutch as | ||