What is the function of a car tachometer?
2 Answers
The function of a car tachometer is to reflect the working condition of the engine. Working principle of the tachometer: Electronic tachometers utilize electromagnetic principles. A piece of iron is connected to the pointer, surrounded by an electromagnetic coil. The electromagnet has three wires: positive, negative, and the high-voltage pack input line, which is the engine's ignition wire. Each time this wire discharges, the engine ignites once, meaning it completes two rotations. Based on this principle, every time the electromagnet is energized, it magnetizes once. The faster the engine rotates, the stronger the magnetic force, causing the pointer to rise. Mechanical tachometer: Mechanical tachometers use a flexible steel wire with one end connected to the engine and the other end connected beneath the instrument panel. The engine's power drives the rotation of the flexible wire. Inside, there is a circular magnet with a bowl-shaped iron disk attached to it, and the pointer is mounted on this disk. The faster the rotation, the quicker the magnetic force moves the iron bowl, similar to the principle of the mechanical speedometer on the left.
I always feel like the tachometer is the car's heart monitor, directly showing how many revolutions the engine makes per minute, giving me confidence while driving. When shifting gears in a manual transmission, it's incredibly useful—when the RPM goes above the redline, I quickly upshift to avoid excessive engine noise and wear; if it's too low and about to stall, I downshift in time to prevent jerking. During highway cruising, it helps me stay in the fuel-efficient RPM range, and when climbing hills, it ensures I avoid overloading and damaging the engine. Even more practical is that at idle, a steady or unsteady needle can indicate issues with spark plugs or the intake system, helping prevent small problems from turning into major failures.
