Tachometers
Description
Tachometers are devices that measure the speed of rotation of a disk or shaft in motors or other machines. Tachometers work on the principle that a motor which is operated as a generator produces a voltage according to the velocity of the shaft. A tachometer is also known as a RPM gauge, or rev-counter, or revolution-counter. Tachometers usually display the RPM (revolutions per minute) on an analog dial, however in recent times digital displays are becoming popular. The initial mechanical tachometers were used for measuring centrifugal force. Some of the features of tachometers include self-test diagnostics, built-in or self-calibration, timers, and counters. Control types and user interfaces include computer programmable interfaces, digital front panels or analog front panels. Available electrical outputs of tachometers include switch or alarm, analog modulated frequency, analog current and analog voltage.
Types
Tachometers can be broadly classified on the basis of data acquisition techniques as:
Contact tachometers
Non-contact tachometers
Other types of tachometers are
Specification
Start/hold
Target distance
Display
Range selection
Measurements
Power
Maximum RPM resolution
RPM range
Accuracy
Advantages
Applications
Tachometers have a wide range of applications:
Electric tachometers are utilized in machinery and automobiles
Tachometers are used in aircraft, automobiles and other vehicles for indicating the rotation rate of the crankshaft of the engine
Tachometers are used in vehicles such as trucks and tractors
Used in stationary engines
Used in rail vehicles
Used in analog audio recording