Product Details

AV685

The Toughest Hollow Shaft Encoder Built!

  • Severe Mill Duty
  • Up to 4000 PPR
  • Replaces Competitive Models Without Rewiring
  • Self-Diagnostic LED & Alarm
  • Outputs Fully Short Circuit Protected
  • Removable Sensors
  • End of Shaft and Thru Shaft Models Available
  • IP66 Enclosure
  • High-Power Output Standard
  • Optional Dual Isolated Outputs
  • 1 Year No-Hassle Warranty

SMARTach™ III Magnetic Encoder, 1-1/8" Hollow Shaft Mount

AV685 hollow shaft encoders survive the worst conditions: dust, dirt, liquid sprays, and temperature extremes from -40°C* to +120°C*!

The durable hollow shaft design tolerates huge axial movements, and withstands more shaft runout than any other encoder available.

The dual, replaceable sensors have fully potted electronics and are interchangeable between AV485, AV685, and AV850. And, they feature high-power outputs that drive long cable lengths easily. These AV5 SMARTach III sensors have the best protection of any encoder—from surges, wiring outputs to power, ground, between phases, or even short circuits!

The universal 5-24V design drives longer cables and is protected against wiring errors and surges.

Adaptive Electronics: At power-up you know you installed it right! The green LED tells you your AV5 Sensor is aligned with the rotor and reading signal. If at any time, the AV5 cannot produce consistent signals, the LED changes to red and the optional remote alarm contact activates. However, the encoder keeps working to give you time to schedule service.  Even wiring errors and short circuits that cause an over-temp situation will be detected and indicated by changing the LED to orange. 

So if you want the highest reliability most durable encoder in your mill, select AV685.

Operating Power (Each Sensor): 5 - 24 VDC*
Current: 100mA, nominal, no load
Output Format: A Quad B with marker (A,/A, B,/B, Z,/Z)
Second Isolated Output: Optional
Frequency Range:
     @5V, @1m cable, 250 kHz Max
     @24V, @300m cable, #8 output, 45 kHz Max   
Maximum Cable Length: 1000'
PPR: 4 - 50000***
Speed: 5400 RPM Max****
Electronics: Fully Encapsulated, IP67**
Temperature: -40°* to 120°C* (150°C rotor)^
Environmental: Electronics: Fully Encapsulated; IP66**; Nema 4, 13 Rating
Chemical: Polyurethane enamel paint protects against salt spray, mild acids, and bases.
Weight: 15-17 lbs. [6-8 kg


* Electrical specifications for SMARTach III model (serial #30,000 or higher), consult Nidec Industrial Solutions for earlier model specifications.
** Certain connector options may reduce IP rating.
***(PPR) Standard maximum PPR is 5000. Consult Factory with your application for PPRs up to 50,000.
**** (Speed) Maximum RPM may be limited for PPR > 2,500. Consult Factory with your application.
^ -20°C to 80°C Standard, requires high-temperature model and instrument air feed for 120°C rating

All dimensions are in inches [millimeters].
Specifications and features are subject to change without notice.


  • SMARTach II sensors find problems before they cause failures
  • Replaces Avtron M585, M685; Dynapar HS56, HS85 models
  • Optional K661 signal converter for direct replacement of analog tachs (BC42, 46, etc.)
  • Mix and match any PPR’s
  • No sensor shimming required
  • Dual oversize bearings, spaced farther apart
  • Synthetic bearing lubricant for longer life
  • Optional overspeed switch
  • Optional shaft grounding
  • Huge range of stub shaft adapters available to fit shafts from 1 3/8" to 12" & most motor brands

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Compititive Products

  • Avtron's AV685 encoders replace many competitive models, including:


    Lakeshore/Northstar: HS85, H8, HS56, H5, HD


    AV685 is also a great replacement for analog tachogenerators coupled to large brake motors including:

    General Electric GE BC42, BC44, BC62


    It also directly replaces older encoder models from Avtron, including: M585, M685, M3-5, M4-5


    For direct model replacements, try our cross reference page

    or

    Contact Us

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