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).
Technical letter about rectifying a fuel gauge issue by modifying the petrol exit hole on a bell plate.
| Identifier | ExFiles\Box 44\4\ Scan071 | |
| Date | 3rd May 1929 | |
| Messrs.Rolls-Royce,Ltd., Date 3.5.29. Page 2 piston should be between 3 and 4 seconds. The resistance to the flow of air appears to lie almost entirely in the 17 feet or so of air line, the internal bore of which is only .050". Owing to the small diameter tube at the tank unit end, we do not think it would be practicable to try and restrict the flow by one small orifice at the end of this line, as it would have to be such a very small hole that it might become blocked or impracticable in manufacture. In our view, from observing the tests in the glass vessel in which we have been experimenting with the air delivered by the pump recently, the whole secret of being able to correct the gauge with one stroke of the pump lies in not spilling the air which is delivered to the tank unit, and this can only be done by letting the petrol escape from the bell at a sufficient rate to admit the air delivered by the pump at a reasonable speed. This can be conveniently done by increasing the petrol exit hole from the bell chamber to approximately the size of the air entry hole. We are sending you herewith a bell plate drilled accordingly, which gives perfectly satisfactory results, and all the air delivered by the pump in 3 to 4 seconds is collected, and the gauge corrected to the full capacity | ||