What is a Vehicle Tachometer?

[LaSamantha]

The tachometer in a car refers to the rotational speed of the car's engine, indicating the number of revolutions per minute (RPM) of the engine. The tachometer is typically located within the instrument panel, placed symmetrically alongside the speedometer. Additional details about the tachometer are as follows: 1. Principle: It receives the pulse signals generated when the primary current in the ignition coil is interrupted and converts these signals into a displayable RPM value. The faster the engine rotates, the more pulses the ignition coil generates, resulting in a higher RPM value displayed on the tachometer. 2. RPM: All car engines have an RPM at which they output maximum torque. When the transmission is in a certain gear (except the highest gear), and the engine reaches the RPM for maximum torque output (e.g., 3000 RPM), the vehicle speed will inevitably reach the maximum speed that gear can handle, at which point a gear shift (upshift) is required. Typically, when the RPM increases to a certain level, the engine noise becomes louder, necessitating an upshift. The optimal time for shifting is generally when the engine RPM is between 2500 and 3000 RPM.