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 design and issues of petrol tank level indicators, fillers, and vent pipes, comparing different schemes.
| Identifier | WestWitteringFiles\G\June1921\ Scan84 | |
| Date | 28th June 1921 | |
| Contd. -2- because it is a type which folds down over the back of the petrol tank. Springfield appear to have dropped the demand for the reserve compartment. I believe their attitude is that if a reliable level indicator is used that the reserve compartment is not essential. They have altered the position of the petrol level indicator because they say when it is in the centre of the tank at the rear, it is obstructed by the type of luggage grid they fit. Fixing the filler on to the top of the tank will overcome all the difficulties of a vent pipe. Tests we have taken show that it is necessary to have a vent pipe .625" dia. in order to allow the air to escape quickly enough to fill the tank in two minutes. It appears as though it would be a difficult job to make a neat arrangement of a vent pipe of that diameter. The filler on the tank as shown on Springfield's scheme A.552, we consider is the best position for filling the tank at the American Filling Stations. Petrol Level Indicator made by the Boston Gauge Company. The Petrol Level indicator fitted to 4.EX Car is quite strongly made mechanically. The scheme is very similar to our design. The weakness, as fitted to 4.EX Car, is that the indicator has been designed to work horizontally. The support for the magnetic indicator needle is on the needle point and in the position the gauge is fitted to 4.EX Car it is only the front glass which prevents the needle from falling off. Mr. Olley in his memo. points out that with the vertical indicator they have trouble with drops of water forming on the glass which causes the contd:- X3896 | ||