Tachometers, in their most basic form, are devices that measure the speed of an object. Commonly, they measure the rotation of a mechanism, like the motor shaft of a car. Traditionally, tachometers are scales with a needle that points to the current speed in RPM (revolutions per minute). However, with the arrival of new reading systems, the use of digital tachometers has increased considerably.
The scale gives the driver the reading of the tachometer. In a car, the scale is located on the board. The instrument measures the RPM of the drive shaft. The device is necessary to regulate the hardness with which the motor is working. However, the way in which the measurements are taken may vary.
Motors with ignition systems use a small generator connected to the motor drive shaft. In this case, the tachometer is, in fact, a voltmeter, which means that it counts the voltage pulses in the ignition system. The output voltage is proportional to the speed of the axis, whereby the measurement of the voltage becomes an accurate measurement in RPM.
The voltage is generated through a permanent magnet on the shaft. There is a gear wheel made of iron, which is magnetized as the magnet passes through the teeth. Then, as the magnet rotates away from the teeth, the wheel demagnetizes. As these changes occur, an electric field forms around the permanent magnet. This field affects the electrical charges in a coil that surrounds the magnet, generating electricity. As the tooth approaches the magnet, current flows in one direction in the coil. As the tooth moves away from the magnet, the current in the coil changes direction. The tachometer reads the frequency with which the current of the coil changes direction.
Also, if the motor spins faster, the change in the magnetic field becomes more radical, generating a higher voltage. The tachometer also uses this information to inform its reading.
A simpler, though less common, a method is to measure the rate at which sparks are released inside the cylinders of the engine. This is only useful in a gasoline engine, which uses spark plugs to provide the explosive heat energy that drives the vehicle.
A more modern version that is rapidly gaining popularity due to its convenience and accuracy is the laser tachometer. This does not require physical contact between the tachometer and the motor shaft. It sends infrared light to the axis. A place on the rotary axis is reflective. The tachometer measures the rate at which the light is reflected on the tachometer.
Once you are familiar with it, there is much that can be said about the way the car is running with only the sound and feel of the engine. If your car has a tachometer, you do not have to use conjectures to diagnose the engine situation. Tachometers are devices that measure the force with which the engine is running. The measurement of the number of revolutions per minute, which is a speed indicator for the engine. Drivers of vehicles with a manual transmission should routinely check their tachometer to make sure they are not stressing the engine and driving at the most efficient engine speed. Instructions
1. Learn engine idle speed. Most engines idle around 1000 RPM, although the use of power brakes, air conditioning and power windows can reach that low rate.
2. Keep the tachometer RPM near the red line of your car when accelerating. The shift to a gear greater than 75 percent of the capacity of the red line must allow sufficient power to accelerate to an acceptable speed for traffic in the city.
3. Keep your tachometer between 40 and 60 percent of the red line when driving. Keeping the engine speed down reduces engine wear and prolongs gas mileage. You will routinely have to scroll up and down to keep the RPM in this range
4. Avoid the engine brake -. Sudden changes down – when decelerating, they push the tachometer past the red line. This can damage the motor.