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).
The performance and qualifications of a Salerni coupling fitted to a 7 HP Fiat.
| Identifier | ExFiles\Box 52\4\ Scan069 | |
| Date | 17th April 1929 | |
| X.4510 R. {Sir Henry Royce} from DA. {Bernard Day - Chassis Design} c. to SG. {Arthur F. Sidgreaves - MD} Hs. {Lord Ernest Hives - Chair} E. {Mr Elliott - Chief Engineer} DAL/M17.4.29. SALERNI COUPLING. Mr. Hardy and I tried a 7 HP. Fiat fitted with a Salerni coupling. As far as we could judge in the short run we had it appeared to do what was claimed for it - that is to say : (1) One could change gear in any direction at any speed without noise or shock, rapidity of change up being dependent on strength of clutch stop. (2) One could coast at will by simply depressing the clutch pedal and letting ho. (3) The coupling could then be re-engaged at any time by either accelerating the engine or depressing the clutch pedal again. (4) If the engine has stopped during coasting it could be re-started by depressing the clutch pedal and holding it out for a second or two while the gearbox was speeded up to synchronism by the friction device. There were the following qualifications : Though a good change in any direction could be made without fail by anyone, to make a perfect change, that is with out the slightest noise or shock, a certain amount of skill or rather practice, was required. A few miles of driving would probably be sufficient to acquire it. It was not to be compared with the difficulties of the conventional box. The fact that the Salerni clutch jaws must be home before the full torque comes on them requires a means of prevent- ing the engine clutch taking fully hold before the jaws. As designed by Salerni it appeared rather liable to get out of adjustment. Also, every time when changing gear, in order to bring the clutch stop into operation, it was necessary to push the pedal right down to the floorboards. This seemed to us to be a rather objectionable feature. Additionally, when it was required to re-start the engine after stalling, it was necessary to push rather hard for the few seconds while the gearbox was being speeded up to synchronism. We think this was not quite satisfactory as arranged. contd :- | ||