All About the Use of the Tachometer

Today, a little culture and especially some clarification on the use of your tachometer. The word is a little barbaric and yet it designates a rather practical instrument once we know how to use it!

The tachometer or "tachometer scale " is a tool whose purpose is to measure the speed of movement of an object or a person in motion. In watchmaking, it corresponds to the graduated dial and calculates the average speed (usually in kilometers per hour) over a given distance. It usually works with the second hand.

We find the tachometer function on chronograph models. It can also be displayed on the dial screen of some digital watches like Naviforce watch.

Manual

On a tachometer, the information is read between the second hand and the corresponding scale, for a maximum of 60 seconds. To use it, you must start the chronograph at the first distance marker, then stop it at the next marker. So you get the average speed between these two benchmarks. The calculation is often done on the basis of a distance of 1000 meters (1km).

Take a more concrete example: you are driving on the road, from a landmark (a terminal for example), press the push button activating the chronograph mode (it is usually the button at the top right) of the dial). Press it again when you cross the second mark (second mark). Looking at the number on which the second hand has stopped, you will get the average speed of your vehicle (depending on how long it took to travel the distance).

If the second hand is over 60 for example, it means that you have moved at 60km/ hour.

On the other hand, if the duration is greater than 60 seconds, the distance to be measured will have to be proportionately shorter. For example, if you measure the time over 500m, it will multiply the value obtained by 2. Know that tachymeter is still a more accurate tool over a long distance (1000m or more).

The different types of tachometers

The tachometer with specified scale: graduation based on 1000 meters, it indicates the speed in kilometers per hour.

The tachometer with unspecified scale (Bulova): the distance is not indicated here, so we must assume that the calculations are done on 1000 meters.

The tachymeter with two levels of scale (Baume Mercier): several graduations are present on the telescope, the first being based on 1000 meters and the second on 100 meters.

Some tachometers may be in the center of the dial (Baume Mercier) and not only around.