The Mechanism of Fuel Gauge with working details
Working Mechanism of Analogue and Digital Fuel Gauge

All vehicles need fuel and the ones which run on fossil oil definitely need good fuel gauge. These days vehicles have a digital monitor but old vehicles have a gauge with a needle. These are interesting things which work with electro-mechanical parts. The fuel gauge is one of the most important indicators in a vehicle. We can assess the safe speed of the vehicle while driving but we can’t know the fuel situation so we should make sure it is always in working condition.

Fuel gauges operate on electrical resistance, using a float with an attached metallic rod as the internal ‘needle’. A wiper conducts electrical current from the rod to the gauge and the more of the rod that’s exposed, the less conductive it becomes, which in turn reduces the fuel gauge level. This older system is effective but works on a relative scale. We can never be sure just how close to empty the tank is.

Modern fuel gauges work off the same principle but add a microprocessor to read the resistance in the tank. They can also compensate for the shape of the tank, calculating the volume of fuel remaining far more accurately. Even better, the microprocessor can ‘dampen’ needle movement, meaning that your fuel gauge doesn’t swing wildly as you turn corners or climb hills, which sloshes the fuel in the tank, along with the float, exposing more of the rod.

Analogue Fuel Gauge Working Mechanism

In the conventional older system, there is an oil tank, metallic road, battery and a variable resistor in the whole fuel gauge wiring system. The major player is resistance or change in resistance. Inside the tank, there is a float which sits at top of the fuel as it is light. The float is connected to a metallic rod is connected to a variable resistor. The resistor circuit gets the power from the battery. There are various regions in resistor with a different value of resistance. This is required to control the current as of the position of connecting rod changes.

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So it is mainly controlling current flow to the gauge using a resistor that is controlled by the level of oil in the vehicle’s tank. If the oil level drops then float also drop which changes the value of the current sent to the gauge or needle. Usually, the current is lower when the level drops and when the level is up, the current is also up. If the oil level is high then the current value is different and the needle sits in a different position. So as the vehicle moves and consumes oil, the level changes and so does the position of the needle. This is basically how the analog system works.

Modern Digital Gauge Mechanism

Nowadays companies are manufacturing vehicles with digital speedometer and fuel gauge. These are much more accurate and suffer less from breaking down. These also don’t have the chance of having broken dials. We can see many people having broken analog dials but digital ones don’t break easily. Higher accuracy is best for everyone and mainly consumers or drivers.

Fuel Gauge Indication
Fuel Gauge Indication

In newer systems, microprocessor and other electronic circuits are used for reading resistance and getting accurate data. Instead of a mechanical needle that works on the principle of electromagnetism, there is a versatile digital screen. The digital indicator uses new LCD or LED screens to display the data. In modern vehicles, a new parameter is shown known as DTE (Distance to Empty). The old analog gauges show the amount of oil left but the DTE system shows how much distance we can travel with the remaining fuel.

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Some Tips

We have seen many jokes and pictures on the internet about people’s mistake while filling the fuel. The gas station may not have a hose in both directions so you can look for the input before parking or stopping.

There will be a small arrow-like pointer or sign near the indicator icon which actually indicates where the pump must be faced. The pump or station machine must be at the side indicated by the fuel gauge indicator. Also always keep your vehicle in good health and do regular servicing for longer life.

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