Everything you need to know about tachometer

25-May-2016 16:16 pm 0

Tachometers measure the revolutions of a rotating object to discover the speed at which it is rotating. Almost all the vehicles from buses to trucks to trains to planes have tachometers. They are also important in fixing machinery performance and conducting maintenance inspections. These meters are also used for monitoring turbines, maintaining quality control, measuring machine speed.speedo-253650_1920

The meter on the right of the dashboard is a Tachometer. The red part indicates when the engine is under restraint.

A tachometer is used to measure the rotation speed of any rotating objects. There are two kinds of Tachometers-Analog and Digital. Analog Tachometers (with a needle and a scale) tells you the rpm of the shaft at that point of time. It can’t store values and track the performance like the Digital tachometers do. A digital tachometer also has better accuracy and convenience.  

Another classification for tachometers is between Contact and Non-Contact/laser Tachometers. Contact tachometers use the roughness of the rotating object to get the value of rpm and always need to be in contact with the rotating object. Non-contact/laser tachometers beam infrared/laser light to measure no. of frequency changes per second which give the rpm. 

  1. If the rotating object is highly polished, apply a reflective tape (if you can’t get one, stick a piece of paper) and aim laser on the tape. It provides the necessary roughness for an accurate measurement. A contrast in colour or lustre also increases the accuracy.
  2. If using a contact tachometer, extra precaution is to be used in the proximity of a rotating object and if the speed of rotation is high and the place is hard to reach, use laser tachometer instead.
  3. Use only the charger that comes with the product to make the battery last longer.
  4. As the range of the tachometer increases, so does the price. So before buying a Tachometer, it is necessary to consider how you plan to use it. If the highest your rotating object can ever go is 5000 RPM, so need not buy a tachometer with a range of 20000 RPM.

One of the major uses of tachometers is to calculate the rpm on engines drive shaft to see if that gear is unsuitable under prolonged use at high speeds (lubrication becomes insufficient which impacts the engine). While placing a tachometer on a car, it becomes essential that tachometer’s display is easily viewable as well it doesn’t obstruct the line of sight of the driver.

The Range of a good photo tachometer is 99,999 RPM. For a contact Tachometer, it is 19,999 RPM.  Tachometer price increases with the accuracy. A Lutron Tachometer of 0.1 RPM accuracy is available for ₹6300 and 0.05 RPM accuracy for ₹7300. The long distance range is usually around 1.5 m.
Tachometers also come integrated with other measuring devices like stroboscopes and vibration meters.
Thus, a tachometer is used to measure how fast anything rotates. The correct tachometer depends highly on what your purpose of use is. Hope this article guided you in selecting and using the correct instrument as well as satisfied your curiosity about how this instrument works.
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Everything you need to know about tachometer
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This article explains everything that you need to know about tachometer. It also helps you buy a tachometer.
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