Milli-Speed Switch


The Milli-Speed switch sensor with 4-20 mA linear output signal is designed to detect belt slip, belt underspeed, stop motion, low speed or zero speed on bucket elevators, conveyors, air locks, mixers, fans, grinders and many other rotating machines.  Totally sealed and simple to calibrate, the Milli-Speed works in the harshest of conditions.

An analog inductive sensing device located in the nose of the Milli-Speed enclosure will detect a metal target. This target can be an existing bolt head or device attached to a shaft, such as 4B’s Whirligig® sensor mount.

The Milli-Speed is designed to operate over a speed range of 20 to 3,600 PPM (4-20 mA output).  During installation, the Milli-Speed is set to the normal running RPM by simple magnetic calibration (17 mA output).  A 20 mA output signal occurs when speed is higher than the calibrated normal running RPM.  A 4 mA output signal is produced when speed falls between 0 to 10% of the calibrated speed.



  4B Milli-Speed 4-20 mA Output Speed Sensor  

• 4-20 mA Linear Output


• Simple Magnetic Calibration


• Loop Powered (2 Wire)


• Totally Sealed Construction (Submersible)


• Easy Installation with Whirligig® Sensor Mount


SpeedMaster™ Compatible for Accurate Testing

  Product Questions? (309) 698-5611Phone or Email  Email    
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  • Specifications
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  • Accessories
  • FAQ's
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  Milli-Speed Technical Specifications:   Literature:  
  • Power Supply - 17 to 30 VDC   Product Datasheet Download PDF  
  • Load - 500 Ohm (Typical)   Full Line Product Catalog Download PDF  
  • Speed Range - 20 to 3,600 PPM (Pulses Per Minute)   (See Downloads for more literature)  
  • Sensing Range - 11/32 in. (9 mm) Max. Ferrous Target      
                                     7/32 in. (6 mm) Max. Non-Ferrous Target   Technical:  
  • Operating Temperature -13° F (-25° C) to 158° F (70° C)   Product Manual Download PDF  
  • Calibration - Magnetic      
  • Outputs - 1. Over Speed 20 mA (123% or More of Calibrated Speed)   Product Dimensions:  
                      2. Calibrated Speed 17 mA (100%)   Download AutoCAD .dwg (AutoCAD)      Download PDF .pdf  
                      3. Zero Speed 4 mA (0 - 10% of Calibrated Speed)      
  • Output Accuracy - +/- 0.2 mA      
  • Response Time - < 1 Second (Typical)      
  • Overall Resolutions - 0.3% (22 mircoamps)      
  • LED Indicator - Blue LED Indicates Target Dectection      
                                Green LED Acts as a Calibration Aid      
  • Cable - 6 ft. (2 m) 2 Conductor (Loop Powered)      
  • Protection - IP67 (Dust and Water Tight - Fully Encapsulated)      
  • CSA Class II Div 1 Groups E, F & G (U.S. & Canada)      
  CSA - USA & Canada        
  Part Numbers and Accessories:      
  • MIL8001V4C ~ Milli-Speed Switch      
  • WG1-4B-4 ~ Whirligig® Shaft Sensor Mount      
  • MAG2000 ~ Mag-Con™ Magnetic Connector for Whirligig      
  • SM2 ~ SpeedMaster™      
  Literature:   Product Dimensions:  
  Product Datasheet Download PDF   Download AutoCAD .dwg (AutoCAD)      Download PDF .pdf  
  Full Line Product Catalog Download PDF      
      Case Studies:  
  Technical:   Hazard Monitoring Overview - GEAPS Download PDF  
  Product Manual Download PDF      
  Note: Product manuals for older part numbers can be      
  found under the Technical Support area.      

Whirligig® - Shaft Sensor Mount

The Whirligig is a fully guarded target for easy mounting of motion sensors. It is a universal shaft sensor mount suitable for all industry standard cylindrical or DIN style inductive sensors.  The Whirligig is available with 1, 2, 4 or 8 pulse targets, and attaches to the machines shaft by a 1/2 in. tapped hole or magnetically using the Mag-Con™ adapter.

See Whirligig

SpeedMaster Speed Switch Tester

SpeedMaster™ Speed Switch Tester

The SpeedMaster™ with Pulse Pilot is the only device that accurately tests the calibration of a speed switch, and allows testing of the alarm and shutdown features of the sensor while installed on the machine shaft.

More Info

  What voltage is needed for the Milli-Speed?  
  The Milli-Speed is looped powered and requires 17 - 30 VDC.  
  How do you calibrated the Milli-Speed?  
  The Milli-Speed is calibrated with a magnetic using the calibration point on the front of the sensor, please refer to the  
  operation manual for details.  
  Why is the Milli-Speed not working when mounting to the Whirligig?  
  There are two sets of holes in the base plate of the Whirligig, be sure to use the top holes to mount the Milli-Speed  
  flush to the Whirligig guard and target.  
4B Milli-Speed 4-20 mA Output Speed Sensor
4B Milli-Speed 4-20 mA Output Speed Sensor
  SpeedMaster (SM2) Sensor & System Tester