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).
Secret report on the failure of a fabric coupling on car 98-NK after 10,000 miles, detailing the nature of the fractures and discussing design constraints for a replacement.
| Identifier | ExFiles\Box 66\4\ scan0125 | |
| Date | 31th March 1925 | |
| From AJS. [REDACTED] c. to H.R. [REDACTED] SECRET. Re Failure of Fabric Coupling on RAC.Car. 98-NK. The fabric taken from the coupling on this car after 10,000 miles shewed radial fractures extending from the periphery of the disc towards the centre, but not going as far as the hole. The fractures were confined to a position along the radial edge of the re-inforcing plates leaving the plates in some cases as it were attached to radial tongues of fabric. We understand that the fracture was not known of until dismantling the parts. We have not had an opportunity of examining the parts of the coupling which failed, other than the fabric and its plates, as a new disc has been fitted to the original spiders (we understand that no damage to these and the bolts was evident). The diameter of the disc cannot be increased to any appreciably extent, as its metal sheath, which is about 50 thous: thick, now clears the starter gear, slider bearing housing and gear box arm by about .075, and it is not thought advisable to eliminate the sheath for the sake of so small a gain in diameter. We can, however, add a little to the thickness. As designed the disc was .500 thick with steel re-inforcing plates | ||