Avtron M4 Large-Bore Encoders

Avtron M4 Large-Bore Encoders

Step up to Magnetic Durability!

  • Heavy Mill Duty
  • Immune to water, oil, dust & dirt
  • Up to 1200 PPR
  • No couplings required
  • Heavy duty seals
  • Rugged cast housing
  • Available in thru and end of shaft models
  • Fits large shafts directly
  • 1 Year No-Hassle Warranty
Outline Drawing
Avtron M4 large bore heavy mill duty magnetic hollow shaft encoders fit motor or load shafts from 1 1/2" to 2 3/8" [48-60mm]. Looking for M4-1 or M4-2 or small-bore M4 models--these have been replaced by AV485 and HS45 upgrade models respectively.  Use our cross reference page for these models

Forget tiny hollow shaft optical units that require shaft reduction and special protection! M4 magnetic heavy duty encoders can accommodate up to a 2 3/8" shaft directly and are designed for use in mill environments with water, oil, moisture, dust, and dirt.
The M4 magnetic sensor system is far more durable than optical sensors.  M4 encoders offer a large variety of connector and mounting options to replace virtually any existing encoder or tachometer. Upgrade to an M4 encoder for maximum uptime!
Operating Power
    5-24 VDC, 5-18V, 12-24V; Current 120mA, no load
Output Format: A,A–, B,B–; Optional Marker Z,Z–
Frequency Range: 0 to 100 KHz
PPR: 240-1200
    5000 RPM Max. Std., shafts 1 1/2" to 1 5/8" [38mm-41mm] 
    3600 RPM Max. Std., shafts 2" to 2 3/8" [48mm-60mm] 
    (for higher speeds, consult factory)
Temperature: -40°* to 85°C (*-20° standard)
Chemical: Polyurethane enamel paint protects against salt spray, mild acids, and bases
Weight: 7 lbs.

All dimensions are in inches [millimeters].
Specifications and features are subject to change without notice.
  • Available C-Face tether kits (4.5" to 16")
  • Available threaded rod torque arm
  • Optional OSHA finger guard
  • Highly resistant to electrical and magnetic motor and brake noise
  • Optional second output can be alternate PPR
  • Available shaft grounding kit
  • Replaces Lakeshore/Northstar HS56, HS85
  • 1 Year No-Hassle Warranty
Industry General Food & Beverage Pulp & Paper Wood Products Wind Power Crane & Hoist Metals Mining Marine Oil & Gas

Light Mill Duty

AV20, AV25, AV32, AV6A, AV6M, HS25A, HS35A, HS6A, HS6M, K661,

Mill Duty

AV32, HS35M, K661, M185, M3, M3(small), RAHS35M

Heavy Mill Duty

AV115, AV125, AV45, AV5, AV56, AV56S, AV67, AV85, AV850, AV850Test, AVSK, Carlen Replacement, HS45, K661, M4, M4(small), XR115, XR12, XR125, XR45, XR4F, XR5, XR56, XR85, XR850, XR97, XRB1, XRB2

Severe Mill Duty

AV12, AV30, AV485, AV5, AV685, Carlen Replacement, HS40, K661, M484, M6, M6C, M7, XR12, XR485, XR5, XR685, XR97, XRB1, XRB2,
Avtron's M4 large bore encoders directly replace and provide a great upgrade from competitive optical encoder models, including:

BEI:  HS45 encoders

Dynapar:  HS35, HS35R encoders

Northstar:  HSD35, HSD37, HSD38, HS56, HS85, Magcoder, MH encoder

Leine and Linde:  861, 862, 863, 865 encoders

Baumer Hubner:  AG 14, EGZ 14, HOG 12, HOG 161

And other hollow shaft mount encoder models, shaft sizes 1 1/2"- 2 3/8" [48mm-60mm], including Avtron M3 optical encoders.

For direct model replacements, try our cross reference page
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In This Section

  • 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.

  • Coupled/Coupling

    Refers to a flexible device that is used to link a solid shaft encoder to the shaft to be monitored. Avtron strongly recommends isolated, flexible disk style couplings wherever possible to maximize encoder bearing life. For large axial shaft movement, splined couplings should be used.

  • Heavy Mill Duty

    Heavy Mill Duty encoders are designed to withstand temperature cycling, extreme temperatures, contaminants, bearing loads, and physical force.

  • 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.

  • Incremental Encoder

    An encoder that produces pulses in proportion to distance moved or rotated. Incremental encoders can also have a marker pulse Z, Z NOT (, ) once per revolution to provide a position reference. Avtron produces a full range of incremental rotary encoders.

  • Magnetic Encoder

    Magnetic and magnetoresistive encoders typically use a magnetized rotor with north and south poles lined up around the perimeter of the disk. A magnetoresistive sensor detects the transitions, and these are the counts or pulses generated by the encoder. Magnetic encoders withstand dirt, dust, water, and temperature changes far better than optical encoders.

  • PPR

    Pulses Per Revolution. Most Avtron encoders output quadrature pulses, with four times as many lines as pulses. Often lines can be counted in the drive/speed controller for higher resolution applications.

  • Torque Arm

    A type of anti-rotation arm used to mount hollow shaft encoders to large frame motors. It features a threaded rod for adjustable radius.

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