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).
Blueprint showing different views and modifications of a drop valve.
| Identifier | ExFiles\Box 40\4\ Scan323 | |
| Date | 30th October 1929 guessed | |
| [ "DROP VALVE", "AV 226", "Fulcrum", "Length of lever", "Increased length of lever by 50%", "New Fulcrum" ], | ||