Electromagnetic Tooth Clutch

Electromagnetic Tooth Clutch

Electromagnetic tooth clutches offer the greatest torque in the smallest package size.

Because the clutches can be made for zero backlash, they are very good for printing applications where a number of stations need to be timed together, but occasionally are required to disengage. The units can be made with a single position option to allow precise timing. Tooth clutches are also ideal for applications that are engaging at very low rpm. Gear box and machine tool applications are also ideal for tooth clutches.


  • High torque/compact design: Tooth clutches provide the highest torque per size of any electromagnetic clutch style.
  • Single position style available: Optional tooth clutches can offer single position for precise registration applications.
  • No slip: Torque is driven via tooth, so slippage is non-existent when clutch is engaged.
  • Zero backlash: As an option, tooth profile can be made to produce zero backlash when clutch is engaged.
  • Zero drag torque: There is no drag torque in the disengaged position because there is no tooth contact.
  • Wet/dry applications: Tooth clutches can be used in either wet (oil/gear box) or dry applications.

How It Works

Engagement: Electromechanical tooth clutches operate via an electric actuation, but transmit torque mechanically. When voltage/current is applied to the clutch coil, the coil becomes an electromagnet and produces magnetic lines of flux. This flux is then transferred through the small air gap between the field and the rotor. The rotor portion of the clutch becomes magnetized and sets up a magnetic loop, which attracts the armature teeth to the rotor teeth. In most instances, the rotor is constantly rotating with the input (drive). As soon as the clutch armature and rotor are engaged, lock up is 100%. (Because of this instantaneous engagement, tooth clutches cannot be engaged above 50 rpm.)

Disengagement: When current/voltage is removed from the clutch, the armature is free to turn with the shaft. Springs hold the armature away from the rotor surface when power is released, creating a small air gap.

Cycling: Cycling is achieved by turning the voltage/current to the coil on and off. When the clutch is running, there is no relative slip. Torque transfer is 100% efficient.