Tachometers

Tachometers, also known as RPM gauges or revolution counters, are portable devices designed to measure the machines’ rotational speeds in revolutions per minute (RPM). These significant instruments help indicate the status of machines or moving objects by recording RPMs on integrated digital or analogue displays. Due to the robust functionality of tachometers, these devices are common, determining whether machines are operating with accurate efficiency levels. Moreover, tachometers are widely found in multiple industries, including automotive, ships, and aircraft, while some models can effectively measure distance and linear speed. 

Potential Benefits of Tachometers

Tachometers or RPM gauges offer unmatchable benefits, such as:

• They are portable and easy to use.
• Battery-operated with a long operational lifespan.
• Come in various package options.
• Provide precise and real-time measurements.
• Can help diagnose and repair engines, optimising speed and preventing equipment damage.
• Serve as educational tools and are durable.
• Versatile performance with high efficiency.

Operating Principle of Tachometers

The operating principle of tachometers can vary depending on the specific type. For instance, a mechanical tachometer comprises a rotating shaft with an attached magnet. As the shaft rotates, the magnetic field induces a voltage in a coil proportional to the rotational speed, allowing the tachometer to measure the RPM. 

In optical tachometers, a light source, such as LED, and a sensor measure the rotational speed. The light source emits a light beam passing through slots or holes on a rotating disk. The sensor detects the interruptions, generating electrical pulses proportional to the disk rotational speed of the disk. These are used to determine the RPM.

Most Common and Popular Types of Tachometers

A tachometer measures the angular velocity of a moving object or machine. Based on the design and intended applications, tachometers come in various types, including:

Mechanical Tachometers: These tachometers use mechanical components to measure objects’ rotational speed. These instruments often comprise a rotating needle or dial connected to the rotating object and are commonly found in older vehicles and machinery.

Digital Tachometers: Digital tachometers use electronic components and display rotational speed as a numerical value on a digital screen. They can be based on various principles, including magnetic, optical, or inductive sensors, and offer precise measurements and additional features like data logging.

Electric Tachometers: Electric tachometers use electrical signals to measure the rotational speed and can be further classified into the following subtypes:

• Magnetic Tachometers
• Inductive Tachometers
• Optical Tachometers
• Hall Effect Tachometers
• Proximity Tachometers.

Contact Tachometers: Contact tachometers require physical contact with the rotating object to measure speed. They typically use a mechanical or electronic sensor that encounters the measuring object.

Non-Contact Tachometers: Non-contact tachometers, also known as optical or laser tachometers, do not require physical contact with the rotating object. Instead, they use optical or laser sensors to measure the speed. These tachometers are often utilised in space-constrained or hazardous scenarios when contact with the object is not desirable or feasible.

Typical applications of Tachometers

Tachometers or rev counters (short for revolution counters) are crucial instruments that find a multitude of applications in various environments, such as:

• Automotive Industry
• Maintenance and Troubleshooting 
• Industrial Machinery
• Marine Applications
• Manufacturing and Quality Control
• Trains and Aircrafts
• Sports and Fitness
• Laser Equipment
• Laboratories and Research
• Medical Sectors.