Avtron HS35A Encoders

Avtron HS35A Encoders

Tough and Compact!

  • Fits shafts 1/2" to 1"
  • Simple Installation
  • Up to 5000 PPR
  • Unbreakable Optical Disk
  • Wide-Gap Technology: Up to 8X larger gap between sensor and rotor
  • Replaces Competitive Models without Rewiring
  • Fits end of shaft and through shaft applications
  • IP65/Nema 4, 13 Rating: Dust and Liquid Tight
  • Superior Bearings and Seals
  • -20°C to +100°C Operation
  • 2 Year No-Hassle Warranty
Outline Drawing


HS35A encoders fit shafts from 1/2" to 1" easily, using a durable shaft insert. Units may be resized by replacing or removing the insert, enabling our factory, distributors, and customer stockrooms to swiftly meet any need. The shaft insert and insulated bearings also provide isolation from motor shaft currents, while permitting case grounding to meet NEC requirements.

Avtron encoders have superior shaft seals and bearings that stay sealed to keep out contamination caused by temperature cycling and liquid sprays. Our encoder seals are protected by mechanical barriers to prevent flexing or failure, and Avtron’s superior bearings feature synthetic lubricants for even longer life.

Many competitive optical encoder designs risk sensor damage from any vibration or shock: sensors ride less than four thousandths of an inch from the thin, often flexible, optical disk spinning at full motor speeds. Some designs even use thin glass disks in “industrial” products! Avtron uses only unbreakable disks and a sensor to disk gap over 8X larger than the competition.

Our optical HS35A encoders use superior sensor, disk, bearing, and seal technology to give top performance in industrial conditions. Select an Avtron HS35A today!


Operating Power: Volts: 5 - 28 VDC; Current: 50mA, no load
Output Format: A Quad B with marker (A,/A, B,/B, Z,/Z)
Frequency Range: 0 to 125 KHz
PPR: 100 - 5000 standard
Speed: 6000 RPM Max., (for higher speeds, consult factory)
Temperature: -20° to 100°C
Environmental: IP65; Nema 4, 13 Rating
Vibration: 5-2000Hz
Shock: 50G, 11mS duration
Weight: 1.6 lbs [730g]

All dimensions are in inches [millimeters].

Specifications and features are subject to change without notice.

  • All digital, fully integrated design
  • No mechanical adjustments or trim potentiometers
  • Innovative shaft ring retains collar during installation
  • Advanced sensor technology
  • Superior bearings with synthetic lubricant for longer life
  • No extra charge for signal complements and marker pulse (A,A–, B,B–, Z,Z–)
  • Insulated from motor shaft currents
  • Models can be resized by interchanging inserts
  • Optional basket guard adds even more protection
Industry General Food & Beverage Pulp & Paper Wood Products Wind Power Crane & Hoist Metals Mining Marine Oil & Gas

Light Mill Duty

AV20, AV25, AV6A, AV6M, Avtron Elevator Encoder, Cables and Connectors, Encoder Couplings, Encoder Programming Tool, HS25A, HS35A, HS6A, K661, SC65

Mill Duty

AV32, Cables and Connectors, Encoder Couplings, HS35M, HS35X, HS6M, K661, M185, M3, M3(small), RAHS35M

Heavy Mill Duty

AV115, AV125, AV44, AV45, AV56, AV56-Wind, AV56S, AV67, AV85, AV850, AVSK, Cables and Connectors, Carlen Replacement, HS44, HS45, K661, M4, M4(small), XP5, XR115, XR12, XR125, XR45, XR4F, XR5, XR56, XR67, XR85, XR850, XR97, XRB1, XRB2, XRB3

Severe Mill Duty

AV12, AV30, AV485, AV5, AV685, Cables and Connectors, Carlen Replacement, Encoder Couplings, HS40, K661, M484, M6, M6C, M7, XP5, XPH1, XPH8, XR12, XR485, XR5, XR685, XR97, XRB1, XRB2, XRB3,
Avtron's HS35A encoders directly replace many competitive models, including:

BEI:  HS35, XHS35

Dynapar:  HS35, HS35R

Encoder Product Corporation (EPC):  260, 775

And other 3.5" hollow shaft mount encoder models.

For direct model replacements, try our cross reference page
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Related Products

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In This Section

  • A Quad B

    A Quad B refers to the set of output quadrature signals from an incremental quadrature encoder to indicate speed and direction, including complements: A, A NOT, B, B NOT (, , , ). Most Avtron encoders offer A Quad B output at no extra cost.  For more information on quadrature- Wikipedia: http://en.wikipedia.org/wiki/Quadrature_phase

  • Anti-Rotation Arm

    A device used to prevent hollow shaft encoders from spinning with the shaft rotation. It is also called a tether or a torque arm. To prevent encoder bearing damage, anti-rotation arms are very flexible and permit all movements, including axial shaft movement but not rotation.

  • Axial Shaft Movement

    Motor shaft movement in or out, relative to the ends of the motor. Often motors that use roller or sleeve bearing construction have more axial shaft movement. Most Avtron modular encoders tolerate +/- 0.050" of axial movement maximum. Use hollow shaft encoders for high axial movement motor styles, such as MD motors. Most competitors’ modular encoders tolerate much less axial movement than Avtron products.

  • Encoder

    A device which indicates position and speed via a set of digital outputs. Incremental encoders output quadrature (A Quad B) signals, and may add a marker pulse once per revolution.  Absolute encoders typically indicate position via a digital message, a set of parallel outputs, or analog values.

  • Hollow Shaft

    Hollow Shaft encoders mount by passing the shaft of the motor into or through the encoder. Hollow shaft encoders are easy to mount and replace but are vulnerable to damage. Also, the weight of the encoder must be considered for small motor shafts < 0.75" diameter. Avtron offers a full range of hollow shaft encoders, including: AV685, HS25A, HS35A, HS35M, M3, M4, M6, M7, XP45.

  • IR LED

    Infra-Red Light Emitting Diode is the light source for an optical encoder.

  • Light Mill Duty

    Light Mill Duty encoders are designed for industrial applications but must be protected from contamination, temperature cycling, and physical force, including shock, vibration, and bearing loads. Examples include AV20, AV25, HS25A, and HS35A models.

  • MS Connector

    The most used encoder connector style in North America. Available in 6, 7, and 10 pin versions, with 10 pins being the most common. Avtron offers pin-for-pin exact replacements for competitors’ models using MS connectors. MS connectors are extremely reliable but require soldering. Many users prefer industrial EPIC ® style connectors instead. EPIC® is a registered trademark of the Lapp Group.

  • Optical Disk

    An Optical Disk is typically a glass, metal, or plastic disk with fine lines or slots etched around the perimeter that interrupt the beam of light from the light source to an optical sensor. Optical disks can be quite fragile. Avtron uses only shatterproof optical disks with Wide-Gap technology.

  • Optical Encoder

    An Optical Encoder typically uses a light source shining through, or reflecting off, an optical disk with lines or slots that interrupt the beam of light to an optical sensor. Electronics count the interruptions of the beam and generate the encoder’s output pulses.

  • Shaft Runout

    The wobbling motion produced by a shaft that is not perfectly true and straight. Shaft runout is often abbreviated T.I.R. (Total Indicated Runout).

  • Wide-Gap Technology

    Avtron encoders use special optical sensors and magnetoresistive sensors, combined with proprietary circuit designs to allow the sensor to be located much farther from the magnetic rotor or optical disk. This eliminates sensor crashes and makes mounting easy and forgiving of mechanical variation.

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