Multiple Disk Electromagnetic Clutch

Multiple Disk Electromagnetic Clutch

Multiple disk clutches are used to deliver extremely high torque in minimal dimensional requirements. These clutches can be used either wet or dry, which makes them ideal to run in multiple speed gear box applications. Machine tool applications top the list where these clutches are used.


  • High torque/compact design: The multiplication of surface area in a multiple disk clutch allows for one of the smallest torque to size ratios available.
  • Wet or dry application: Clutches can be used in an oil/gear box environment (wet), or as a stand alone clutch (dry).
  • Fast Response (wet): For fast response special channels are cut in the friction disks to allow the oil to flow faster.
  • High heat dissipation (wet): In an oil environment, the oil is used to take heat away from the friction disks for better heat dissipation.

How It Works

Engagement: Electromechanical 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 magnetised and sets up a magnetic loop, which attracts both the armature and the friction disks. The attraction of the armature compresses or squeezes the friction disks, transferring the torque from the inner driver to the outer disks. (In order for the unit to be used as a clutch, a drive hub is required. This hub would be attached to a pulley, sprocket or coupling.) Within a relatively short time, the load is accelerated to match the speed of the rotor, thereby engaging the armature and the output portion of the clutch.

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 minimal drag.

Cycling: Cycling is achieved by turning the voltage/current to the coil on and off. Slippage should occur only during acceleration. When the clutch is fully engaged, there is no relative slip (if the clutch is sized properly). Torque transfer is 100% efficient.