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Applications and How-Tos, How It Works

Electromagnetic Tooth Clutches – How they Work

Jonathan Bullick | September 22nd, 2017
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Tooth clutches are electrically engaged and provide three times more torque than friction clutches. This video shows how they work.



KEB is a leading manufacturer of electromagnetic tooth clutches. Compared to the typical electromagnetic friction clutch, a tooth clutch has the advantage of offering roughly 3 times more torque in the same diameter.


This is particularly advantageous for medical and printing machinery, where space is of concern. This video describes how a KEB tooth clutch operates.


First, lets get acquainted with the main clutch components: The primary drive shaft typically contains a stationary electromagnet which is fixed with a flange or torque tab. A rotor is fixed to the primary driving shaft with a key or other connection.


Next, an armature is riveted to a flat spring. The flat spring is then riveted or screwed to a hub – or in this case, a pulley which is connected to a secondary shaft with a belt. Both the rotor and armature face feature a fine tooth profile, which mates them together.


Here’s how the tooth clutch works: With the primary shaft stopped, the clutch can be engaged by supplying the electromagnet coil with the nominal DC voltage. This creates a magnetic field that passes through the clutch rotor and armature.


The magnetic field’s force is large enough to deflect the flat spring and pull the armature across a small pre-set airgap towards the rotor face. The toothed profile of the armature and rotor mate allowing the pulley to turn synchronously with the primary shaft.


It should be noted that the tooth clutch should be engaged when the shafts are stationary or the tooth profiles could be damaged.


When electrical power is removed from the coil, the flat spring returns and pulls back the armature.


Without the toothed connection, the two shafts rotate independently.


KEB Electromagnetic Clutches

You can read more about KEB’s Tooth Clutches at our Tooth Clutch product page.

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