NCCER Millwright Practice Exam

A mechanical tachometer is typically used in machinery that rotates less than what RPM?

1. 1,000 RPM

2. 5,000 RPM

3. 10,000 RPM

4. 15,000 RPM

The correct answer is: 10,000 RPM

A mechanical tachometer is a device used for measuring the speed of rotation of machinery, typically expressed in revolutions per minute (RPM). These instruments are designed to operate effectively within certain ranges, and for many mechanical applications, they are particularly suited for measuring speeds that fall below 10,000 RPM. When considering machinery that typically rotates at speeds less than this threshold, it qualifies for effective monitoring and measurement by a mechanical tachometer. For example, machinery in manufacturing or milling operations often operates at speeds that do not exceed this level, making a mechanical tachometer an appropriate choice. Understanding this limit helps operators select the right measuring instruments for their equipment. Choosing a tachometer rated for excess RPMs could lead to inaccuracies or potential damage to the device, especially when the machine runs at lower speeds where a different type or model may provide better performance or accuracy. Consequently, the choice of 10,000 RPM reflects the applicable upper limit for the effective use of mechanical tachometers in typical operational contexts.