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).
Improving the lifespan of fabric couplings by comparing riveting and screwed thimble methods.
| Identifier | ExFiles\Box 15\4\ Scan038 | |
| Date | 21th June 1929 guessed | |
| contd :- -2- We find that if we spigot the studs on the spider which carries the coupling we increase the life of the fabric by several hundred per cent. Originally these studs were not spigoted because the fabric could not be got into position if they were spigoted due to the small amount of space available between the gearbox and the cross member. They are not shewn spigoted on your dwg. of the 8S. Coupling. Our joggling tests on the fabric coupling have shewn us that the present screws and thimbles used have very poor life. On our joggling rig, of which you will get a full report later, the screwed supports for the fabric plates fail after 40,000 reversals. The bolts break and the plates work loose and the coupling rapidly disintegrates. If we use the original riveting scheme however and rivet the plates on properly, the coupling stands up to 750,000 reversals. The fabric then gives way between the plates, the plates themselves remaining perfectly tight. The screwed thimble method of securing the plates was adopted because it was said that the Works could not rivet satisfactorily. These screws were never tested or recommended by the Expl: Dept: and have always given us trouble, but apparently they stand up better than badly rivetted pixte couplings. The Works appear to bend the rivets in the centre and we therefore are testing out shoulder rivets with a view to seeing if we cannot get the Works to make a better coupling. Experimentally we find no difficulty in using normal rivets on the couplings providing the plates are bolted together tightly by a bolt before the rivetting is started and the rivetting is done gradually. We think it is essential we should get the best possible job on this new fabric coupling because cont | ||