Odometer and Speedometer

The term odometer comes from the Greek word ‘hodos’ meaning ‘road’ or ‘trip’. As mentioned previously, the term ‘meter’ means a device or instrument for measuring. So, an odometer or odograph is used to measure the distance travelled by a vehicle such as a bicycle or a bus. The first odometers developed in the 1600s were used for measuring the distances travelled by the wagons and other horse-drawn vehicles. The term speedometer comes from the Germanic-Greek hybrid ‘speed’ and ‘meter’. The term ‘meter’ itself means a device or instrument for measuring. So, a speedometer or speedometer is used to measure the speed of a vehicle. Although the speedometer was used as an alternative in the early 20th century and as a quality gadget from 1910 onwards, it is now used worldwide in motor vehicles.

Odometer

Though both the odometer and the speedometer in a vehicle are present as a single instrument yet each has a unique role to play. The role of an odometer is to measure distance by recording the number of rotations of the wheel in each mile depending on the diameter of the wheel. A mile is recorded when the number of rotations is reached, the counter clicks over. Earlier, the counters consisted of five digits unlike now which consist of six digits. Odometers could be electronic, mechanical or both, that is, electromechanical.

Speedometer

Speedometer appears like a dial located right above the odometer counter on the vehicle dash. It measures the speed of a vehicle. Early Romans used marks on the wheels of their chariots to measure and calculate the distance and speed. Now, Science is much more advanced, implementing the use of cables, magnets, sensors or in the case of even newer electronic systems like tech generators which are used for measuring the speed of the moving vehicle. Speedometer has different names for different vehicles- it is a pit log for a boat; for an aircraft, it is an airspeed indicator. Charles Babbage used a speedometer first in the locomotives. In 1988, the Croatian Josip Belušić originally called it a velocimeter.

Differences between Odometer and Speedometer

Odometer is attached to the wheel of a vehicle which measures the distance travelled whereas speedometer measures and indicates the current speed of that particular vehicle. Good speedometers not only let the user pay attention to what the readout is telling about the travel but also about the traffic laws and speed limit where it is driven. While odometers help let the user know when it is time for programmed maintenance and the mileage on the vehicle. Odometer measures the distance in kilometres (km) in India and miles in other countries like  the USA. While a speedometer measures the speed in kilometres per hour (km/h) for India or miles per hour (mph) for other countries.

Odometer	Speedometer
The speedometer’s purpose is to keep track of how fast your automobile is moving	The function of an odometer is to keep a record of a car’s total mileage during its lifespan, along with counting the overall distance covered by the vehicle itself
When the automobile comes to a complete stop, the speedometer resets to zero and progressively climbs as the car proceeds	When the automobile comes to a halt, the odometer stays on the most recent count and increments forward when the car proceeds
Miles per hour or kilometres per hour are the units of measurement for speed	Miles or kilometres are the components for measuring distance
Speedometers in powerful and fast automobiles have higher readings and may reach speeds of up to 800 miles per hour (500 kilometres per hour)	The reading on all autos is typically the same, with a maximum of six digits (999,999)

Role of Speedometers

Speedometer is used to measure the speed of a vehicle at any given instant which is known as instantaneous speed. Nowadays, digital speedometers are used widely which shows more accurate reading. It is generally located on the dashboard of a car or the instrument cluster of a bike. Mechanical speedometers are linked with the gearbox output which provides the output to the wheels and lies downstream of the gearbox. A magnet is linked with the speedometer. Over this magnet, lies a speed cup that stays just above without any physical connection. With the help of the speed cup and indicator rod is connected with the hairspring. With the indicator rod, the indicator housing is connected which shows the speed outside in the speedometer.

Conclusion

The two factors which determine the resale value of a vehicle are- Condition of the vehicle and the Odometer reading. Calculation of mileage not only helps in calculating the economy of the fuel in km/litre but also gives a rough idea of how much fuel should be filled before setting out on a journey. Prediction of life of an existing tyre is continuous use of anything that leads to wear and tear of it. Similarly, a tyre from a renowned manufacturer typically lasts for about 50,000 km. Hence, one can check from the odometer itself after every replacement and after 50,000 km is completed in the odometer when the tyre needs to be changed. In this way, one doesn’t have to keep checking the tire’s conditions now and then, waiting for it to finally break down. Servicing and maintenance recommended completion of distance, servicing needs to be done which one can easily find out from the odometer reading after each servicing.