Extech 461750 Tachometer PocketTach Mini Contact.

PocketTach Mini Contact Tachometer
Surface wheels measure contact surface speeds of rotating (10 to 9,999 rpm) and moving (3 to 6,560 feet/minute; 1 to 1999. 9m/min) objects.

Features Overview
Large easy to read (99,999 count) LCD display. Autoranging with 0.1 percent basic accuracy. Hold button freezes readings on the display. The ergonomically designed and pocket size housing has a built-in protective finger guard.

What is a Tachometer?
A tachometer is a device that measures the angular speed of a rotating shaft in terms of revolutions per minute (RPM). Also, a tachometer can measure linear speed in terms of feet per minute (feet/minute) or meters per minute.

How do Contact Tachometers Operate?
The sensor tip is placed in direct contact with the rotating object. After 2 seconds an accurate reading is displayed. Linear surface speed can also be measured by placing the edge of the wheel on the moving object.

Tachometer Applications
Motor speed, moving fans, pumps, and gears Propeller devices Many other general maintenance, production, and automotive uses.

Which Extech Tachometer Model Is the One for You?
A non-contact (photo) tachometer was designed for applications where it is not feasible to have the tachometer come in contact with the rotating device. This is the case in high-speed applications and/or where the object to be measured is not easily reached. A contact tachometer is also available for applications where direct contact of the tachometer with the object is preferred. You can also select a combination (contact/non-contact) tachometer for the maximum in flexibility.