Original, never used WWII German Luftwaffe 0 – 300 / 0 – 230 L elektr. Vorratsanzeiger Fuel Gauge Fw190, used ONLY in the famous Fw 190 aircraft!
The fuel meter gives the pilot information about the amount of fuel in the fuel tank. This device of the "float system" measures the supply based on the height of the liquid level in the fuel tank. A body floats on the fuel level, which electrically effects a display on the level indicator when it moves up or down. The movement of the float is used to move a tap on a circularly curved resistor, thereby causing a change in resistance. The change in resistance is measured by the display device (cross-winding device).
A spiral groove in the float tube rotates the float around its vertical axis when it moves up and down. A square rod guided through the float axis only takes part in the rotary movement. At the top it has a magnet that moves a second magnet through an airtight partition. The two magnets are not mechanically connected to each other, their coupling is purely magnetic. The upper magnet moves the tap on the resistor as it rotates.
The remaining level warning lamp is switched on by a contact that is activated when the float is in a certain position.