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 development and issues with petrol gauges, comparing Hobson and Nivex models.
| Identifier | ExFiles\Box 15\7\ Scan155 | |
| Date | 24th June 1930 guessed | |
| -2- getting into the capillary no matter how the gauge head was handled. (2) The top joint on the glass tube was improved so that we now think there is little possibility of leakage unless the glass tube itself is actually broken. The bottom joint of the glass tube is now actually made by fusing the metal tube into the glass, and so far both Messrs. Hobsons and ourselves have found this construction to be 100%. (3) The trouble of coupling the gauge up incorrectly and so getting a bead of petrol in the air line has been getting less and less, as the people who have to handle the gauge have become more educated. It is a trouble that exists with the Nivex gauge just as much as the Claudel Hobson gauge, as the capacity of the line between the tank and the gauge has to be made very small in order to prevent the reading of the gauge falling to zero every time the car is left standing for a short length of time. The trouble with the 'Nivex' petrol gauge of which we are sending you a sample with our latest production Hobson gauge, is that the metal bellows which controls the reading of the gauge cannot be made with sufficient accuracy to enable one fixed scale to be used for all instruments. This is obviously a difficulty which will cause trouble if the gauge has to be built to a reasonable price for production in quantities. The other point is that the Nivex gauge is not so well damped as the Hobson gauge. Furthermore, since the Nivex gauge is now a constant reading instrument and there is a considerable amount of flicker movement due to the swishing | ||