odometer and tachometer Combo

• 2022-04-28

Speed odometer, as the name suggests, is composed of two tables: the "speedometer" representing the driving speed of the vehicle and the "odometer" representing the driving distance of the vehicle. The former informs the driver of the speed of the vehicle, so as to facilitate the driver to control the speed and ensure driving safety; The latter indicates the mileage of the car and reminds the driver to pay attention to maintenance and repair. In the past, the speedometer was traditional mechanical, but now it is increasingly replaced by electronic speedometer. The same is true of the odometer, but its numbers can be saved better even when there is no power.

The tachometer is generally presented symmetrically with the odometer. It is a window for us to understand the working condition of the engine. Its indicator multiplied by 1000 or 100 represents the speed of the engine per minute. The tachometer is usually divided into white, red or green areas, which represent the safe speed, dangerous speed or the most economical and applicable speed respectively. The driver only needs to ensure that the speed is not in the red dangerous area. The speed must match the current gear, otherwise it will cause damage to the vehicle.

In fact, the principle is very simple, because the diameter of the car wheel is known, and the circumferential length of the wheel is constant. From this, we can calculate how many revolutions the wheel needs to turn for each mile, and this number is also constant. Therefore, as long as the number of revolutions of the wheel can be automatically accumulated, and then divided by the number of revolutions corresponding to each mile, the mileage can be obtained. Such a simple principle was discovered by the ancients and began to be used. "Jili drum car" is such a device. It uses the above principle and ingenious mechanism to make the wheel beat the drum automatically every certain number of turns. At this time, as long as someone writes it down, you can get the mileage. This device is very ingenious. It can be used both day and night, and can also be used by the blind. It reflects the intelligence of the working people in ancient China. However, if no one on the bus remembers the number of drums, the drum car alone can not accumulate the total distance traveled. And no one knows how many miles the car has traveled after it stops, which is a flaw in the United States.