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 relative petrol levels in a float chamber and outer reservoir.
| Identifier | WestWitteringFiles\N\2October1925-December1925\ Scan283 | |
| Date | 12th June 1925 | |
| R.R. 493A (50 H) (D.D. 31, 12-6-25) J.H.D. EXPERIMENTAL REPORT. -3- Expl. No. REF: Hs{Lord Ernest Hives - Chair}/AJL/LG9.12.25. Fig.1. above shows the relative levels on the float chamber and outer reservoir when working with a full reservoir. A.{Mr Adams} is the level in the float chamber when the float is at the top of its stroke at which point the petrol supply is cut off by the toggle mechanism not indicated. B. is the level in the float chamber when the float is at the bottom of its stroke and petrol is about to be admitted again. Thus the petrol admitted is equivalent to the difference between the levels A.{Mr Adams} and B. - this as previously stated, is arranged to equal .002 galls. C. is the petrol level in the outer reservoir at the time when the float is at the bottom of its stroke. When the float chamber is fitted C. rises equal to the amount of petrol represented by the difference in the levels A.{Mr Adams} and B. owing to the flap valve D.{John DeLooze - Company Secretary} being open. It will be seen from this that the float action is governed by the level C. - when C. falls to the level B., the float operates the valve mechanism and the float chamber is fitted to the level A.{Mr Adams}, the float operates the valve mechanism again, releasing the vacuum in the float chamber, and cutting off the petrol supply - the small flap valve opens and the levels in the float and outer reservoir equalise themselves, these fall together until the level C. is reached when the action begins again. Thus in this case the same quantity of petrol is drawn in every stroke, being the difference between the levels A.{Mr Adams} and B. Fig.ll. shows the case in which, owing to the engine using more petrol than the Autovac can supply or owing to the contd :- | ||