Extech 461891 High Precision Contact Tachometer


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Extech 461891 High Precision Contact Tachometer


  • 461891 Contact Tachometer High Precision
  • 0.05% basic accuracy
  • Make contact measurements of rotating objects
  • Measure linear surface speeds in ft/min or m/min using three accessory wheels provided
  • Recalls Last/MAX/MIN values
Extech 461891 Contact Tachometer High Precision.

Contact Tachometer
Surface wheels measure contact surface speeds (10 to 9,999 rpm) of rotating objects. The memory button holds last reading and recalls min/max readings display. Complete with wheels for linear surface speed (0.2 to 6560 feet/minute; 0.05 to 1999.9 meters/minute) or RPM measurements.

Motor speed, moving fans, pumps, and gears, propeller devices, and many other general maintenance, production, and automotive uses.

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.

How do Photo (Non-contact) Tachometers Operate?
First, a small piece of reflective tape (approximately 1/4-inch) is mounted on the object to be measured. Second, the light beam or laser is pointed at the revolving tape. The reflection from the tape provides a reading to be displayed and updated once per second. For the most accurate measurements, the distance between the tachometer and the reflective tape should be within 6 inches for a light beam and up to 6.5 feet for a laser. Fluorescent or bright ambient lights may interfere with the measurement.

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.

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General Specifications
Circuit Custom one-chip LSI microprocessor circuit
Time base Quartz crystal
Display 5-digit multi function LCD display
Measurements Rotation Speed 0.5 to 19,999 rpm
Surface Speed 0.2 to 6560 ft/min. 0.05 to 1999.9 m/min
Memory Last and Max/Min readings
Sampling Time 1 second
Operating Temperature/RH 32 °F to 122 °F (0 °C to 50 °C) / <80% RH
Power Supply 4 x 1.5V AA batteries
Power Consumption Approx. 10 mA
Weight 0.62 lb (280 g) including batteries
Dimensions 8.2 x 2.8 x1.5" (208 x 72 x 37 mm)
Accessories Cone rpm adaptor, funnel rpm adaptor, surface speed, test wheel, and carrying case
Range Specifications
Rpm 0.5 to 19,999 rpm
ft/min 0.2 to 6560 ft/min
m/min 0.05 to 1999.9 m/min
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    • Extech 461891 High Precision Contact Tachometer