HB21 Bearing Sensors

Maxi-Tronic leads the industry in providing a wide variety of reliable, low cost temperature sensors for all your hazard monitoring needs.


HB21TM sensors are ideal for bearings, gear boxes, bucket elevators, mills, grinders, conveyors, mechanical drives and most other material handling equipment.

Use these “Hot Bearing” sensors with Maxi-Tronic Temperature Controllers and all PLC/PC based systems. Combine with the Maxi-Tronic MaxiScan 12M Underspeed Detection and Temperature Controller for complete hazard monitoring protection.

HB21™ Sensors in Action

  • Easy-to-adjust length for any size bearing.
  • HB21 Series Bearing Sensors allow greasing the bearing without removing the sensor.
  • Easy to install and maintenance free. Just screw the stainless “Housing” into an existing 1/8”, 1/4” or 8mm Zerk tting hole then slide in an “Insert” .
  • Sensing element is located at the bearing race for the most rapid and accurate readings. Brass-tipped for improved thermal conductivity and accuracy.
  • CSA certified maximum ambient temperature rating: 221°F (105°C).
  • Non-hazardous rating: -40°F (-40°C) to 250°F (127°C). Max. 329°F (165°C) on request.

Sensor Type Options:

  • Thermocouple: Type T, others types available.
  • RTD: Industry standard PT100, 4 conductor (2, 3 and 4-wire compatible).
  • PTC Thermistor: “HBRB” and MaxiScan™ compatible.
  • DigiMax™ Digital: “1-Wire”† digital for DigiMax™, PLC, MaxiScan 12/24 Controllers and MaxiTrack™ PC software.


3“ length Inserts for “D” = .25” to 1.5“
4.5” length Inserts for “D” = 1“ to 3”
6” length Inserts for “D” = 2.5“ to 4.5 “;
Longer available

Adjustable Housings:

HB21.HSNG.18 for 1/8” NPT Zerk fitting and #HB21.HSNG.14 for 1/4” NPT Zerk fitting.

  • CSA certified Class II, Div. 1, Groups E, F, G
  • Extremely rugged design.
  • Industry standard TC, RTD, PTC and “1-Wire” digital sensors for industry wide compatibility.
  • Integrated 1/2” NPT conduit fitting.
  • “Simple Apparatus” for Intrinsically Safe installations with an approved barrier.
  • Fully compatible with PLCs, DigiMax, MaxiScan 12/24 controllers and MaxiTrack remote monitoring PC software.



† 1-Wire® Is a registered trademark of Maxim Integrated Products, Inc.