The image shown below is the float gauge RF 9227 intended for fitting to the R type fuel tank.
Originally this gauge unit, which was basically the same as the Bentley MKVI was to be fitted in the side of the tank adjacent to the left hand rear wheel under scheme PL 6959.
In the event Smiths who supplied the gauges could not supply the resistor that was required to make the float unit read linear to the dashboard gauge. The float was therefore position at the front of the tank under scheme PL 7052, but the gauge does not read the last 1.75 imperial gallon of fuel.
Anyone who researches these PL schemes should be aware that although both schemes utilised the original Alloy fuel tank, production R type cars used both Alloy and Steel fuel tanks. In addition the original test poundage for these tanks of 3 lbs sq ins was raised to 6 lbs sq in for production units.
