Definition of a Split Ring Commutator

Updated November 21, 2016

A split ring commutator is a device found in a motor that reverses the direction of electrical current every half-turn of the armature. This allows the armature to spin consistently in the same direction.


Simple electric motors work on something called the catapult, or motor, effect. A wire is wound around a central block, called an armature, which rotates around a spindle through its centre. Electrical current flows in opposite directions through wires on either side of the armature, causing it to rotate.


The split ring commutator keeps the armature rotating in one direction by switching the direction of the current every half-turn. This helps turn electrical energy into kinetic (rotational) energy to power devices such as clocks, power drills, water pumps and even industrial robots.


The split ring commutator is made from two pieces of copper that do not touch each other. One sits on either side of the spindle going through the armature. A piece of carbon is placed against the copper to conduct the electricity to the armature. When the armature spins, the carbon brushes against the copper pieces. This keeps the armature spinning in the same direction.

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Jennifer Gigantino has been writing professionally since 2009. Her work has been published in various venues ranging from the literary magazine "Kill Author" to the rehabilitation website Soberplace. She holds a Bachelor of Arts in film and digital media from the University of California at Santa Cruz.