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).
Continuation sheet explaining the functioning of the Autovac fuel feed system and its interaction with a gauge.
| Identifier | ExFiles\Box 75\2\ scan0193 | |
| Date | 15th March 1927 guessed | |
| O.S. SPEEDOMETER Co. LTD. CONTINUATION SHEET NO. 1. necessary to renew the air in order to assure that the gauge always functions correctly. The phenomena which are produced by the functioning of the Autovac which feeds the carburettor with fuel are used for this. The Autovac sucks in from the tank by means of the Tube T which goes down to the bottom of the tank. Under the effect of the depression reigning in the Tube T, the valve S is sucke up and stocks to its seat. At this moment the petrol rises in the Tube T and acts exactly like in an ordinary device. The autovac stops functioning when the level is attained in the "Nourrice" (the outer chamber of the autovac which feeds the carburettor) of this latter, and the depression is no longer exercised in the tube T; the petrol that was in it returns, by Gravity, to the tank. But at this moment, the depression being no longer felt on the valve S, this latter falls back on account of its own weight, allowing a communication between the tube T and the air at atmospheric pressure. The petrol returning to the tank takes with it bubbles of air when passing the apperture of the valve S. These bubbles drawn along will go out by the end of the tube T and will reassemble at the bottom of the concave of the bell C. If this bell contains petrol, the bubbles will rise by pushing back the petrol as they burst at its surface until the whole of the bell is full of air. This phenomen takes place at each pulsation of the Autovac, that is to say about five times for each kilometre travelled, and suffices amply to maintain the gauge in working order. ---o0o--- GROSVENOR BOND | ||