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).
Comparative analysis of various valve springs, detailing their periodicity, performance, and application.
| Identifier | ExFiles\Box 56\2\ Scan065 | |
| Date | 20th February 1929 guessed | |
| (2) | SPRING. | PERIODICITY. Vibrations per minute. | FIGURE OF MERIT. 90,000 Max. stress + range | REMARKS. | |---|---|---|---| | (1) LeC.9. | 8,180. | 1.1 approx. | This was a very early attempt at a low stress low range spring on the Silver Ghost at Le Can: 1913. It was the ^worst wobbler we have seen & broke itself up very quickly on the spring test rig. | | (2) Silver Ghost. E5193. | 10,500 average. | Small end 1.1 Large end .94 | LeC.9. was followed by a taper spring designed at Le Can: No. E5193. This is a very good spring and is used on many hundreds of Silver Ghosts. | | (3) LeC.1708. now numbered E70442 - standard Phantom spring. | 10,780. | .95 | These springs have been used on all Phantoms. On SS.{S. Smith} they give a bouncing speed of about 2900 RPM. | | (4) LeC.2479. SS.{S. Smith} double valve spring | OUTER 10,400. INNER 10,220. | 1.2 1.18 | Valve gear started bouncing long before it should have done and there was a pronounced period at a lower speed. Bouncing speed 2700 RPM. | | (5) Curtiss D.12 A/C Springs | OUTER 13,120 INNER 14,880 | 1.3 1.33 | The springs are used on a 1.512 port dia. valve. The total pressure exerted is only 21 to 49 lbs. valve closed and open respectively against 58 to 96 for LeC.2479. Max: engine revs. 2300. | | (6) SS.{S. Smith} spring used on 10,000 miles test. | 12,400 | .95 | Bouncing speed probably 3200 RPM. | NOTE: Reverse (5) & (6) so as to read SS.{S. Smith} spring after (4). | ||