The pressure of the fuel is measured by pressure gauge member 1 whose inside chamber is connected to tube 2, immersed in the gasoline tank. Pump 3 is connected to tube 2. The pressure in the housing of gauge member 1 is equal to the pressure of the air above the level of the fuel in the tank because tube 4 is connected to air tube 5 of the tank. A certain air pressure is established in the pump cylinder which is transmitted simultaneously to tank a and to pressure gauge member 1. The air delivered by the pump forces the gasoline out of tube 2. This establishes a pressure in the gasoline gauge system that is proportional to the level of the gasoline. The hand (not shown) of member 1 indicates this pressure on a scale.
$4063$EHP,M$