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).
Failure of a clutch facing on a Phantom III and comparing different materials.
| Identifier | ExFiles\Box 129\3\ scan0231 | |
| Date | 29th April 1936 | |
| X110 To E.{Mr Elliott - Chief Engineer} c. to Wor.{Arthur Wormald - General Works Manager} c. to By.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Smth.1/KW.29.4.36. Phantom III Clutch. We have had a failure of a facing of American "Hyco" material mounted on a Ph.III driven plate. The facing tore across a line of rivet holes whilst a gear change was being made at high engine speed. We have discussed with Ferodos the likelihood of a similar failure occurring with the "No.6" material which we are standardising but they are confident that we shall have no trouble. As "Hyco" is cut out of a square piece of straight woven material it is considerably weaker in one direction than the other. "No.6" is woven in such a manner as to be equally strong in all directions. Another factor which makes "Hyco" more liable to fall than "No.6" is its greater density. "Hyco" has a large inclusion of litharge to accelerate the vulcanisation of the rubber and weighs 60% more than "No.6" in consequence. The loop loading across a radial section of the facing at 4000 r.p.m. with the clutch disengaged, is 780 lbs. for "Hyco" and 506 lbs. for "No.6". In view of the above considerations we do not anticipate trouble due to tearing of the facings on production clutches. We have arranged with Borg & Beck to reduce the depth of the rivet countersinking from 1/16" to 1/32" in view of the fibrous nature of the fabric. We feel justified in doing this in view of the extreme durability claimed for rubber base facings. We suggest that particular attention should be given by the Inspectors to ensure that the countersink is never less than this. Hs{Lord Ernest Hives - Chair}/Smth. | ||