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).
Sales leaflet for the O.S. Automatic Petrol Gauge for under-bonnet tanks.
| Identifier | ExFiles\Box 75\2\ scan0179 | |
| Date | 16th November 1926 guessed | |
| LEFT PAGE: A pressure of 1 1/2 to 7 ozs. It functions by means of a pressure of 1 1/2 to 7 ozs., obtained by the weight of a column of mercury of the same height as the liquid to be measured. This weight is nineteen times greater in the case under consideration (mercury-petrol) and it is therefore possible to use an Industrial Manometer in which the mechanism is exceedingly strong and very accurate. The indicating needle remains absolutely steady no matter how violent the jolts of the car. The O.{Mr Oldham} S. Gauge is Automatic The needle gives constant indication—even when the car is at a standstill—of the quantity of petrol in the tank. Unaffected by Temperature or Altitude. Temperature and altitude do not in any way influence the accuracy of the indications, because the column of air between the manometer and the mercury always places the weight of this latter in equilibrium. The instrument acts as an ordinary static balance. HOW IT WORKS. The gauging instrument consists of a float F joined by means of a flexible tube S to a device on the tank. This flexible tube puts two small chambers B and C in communication. The first (B) is joined to A.{Mr Adams} It is fixed in its upper part to the tube going to the manometer. The second (C) is connected to the float, is movable, and follows with the float the variations in the petrol level; it is subject to atmospheric pressure. The mercury, which constitutes the active part of the instrument, is contained in the two chambers B and C connected by the tube S. It is kept in the tank at the height H by the depression prevailing in the tube going to the manometer. On account of the high density of mercury (19 times greater than petrol) the depression necessary to put the height H in equilibrium will be between 50 and 200 grammes. It is clear, therefore, that, by means of the float the chamber C will cause the height H to vary inversely to the amount of petrol contained in the tank, and that the depression necessary to place the height H in equilibrium will strictly follow this latter. It will be sufficient, therefore, to graduate the manometer so that it shows the registered depression in gallons. PRICES : For Tanks up to 17 gallons capacity ... £2 18s. 0d. For Tanks over 17 gallons capacity ... £3 8s. 0d. RIGHT PAGE: O.{Mr Oldham} S. Automatic Petrol Gauge FOR Under-Bonnet Tanks without a visible Filler-cap. A constant Automatic Indicator for cars in which the Petrol Tank is situated under the bonnet and has no visible Filler-Cap. Fitted to the dashboard of any car, immediately in front of the driver's eyes, the O.S. GAUGE constantly indicates, by means of a red figure on a white background the quantity of petrol remaining in the tank. The legibility of this instrument is unique. Simplicity, accuracy and careful manufacture guarantee its solidity. This elegant and yet practical indicator will soon be found on every car in which the petrol tank is placed under the bonnet. Price 25/- | ||