how the commutator/slip-rings work in a DC motor.

Thread Starter

Charles Flux

Joined Aug 2, 2006
Hello everyone,

In trying to understand the principles at work in a DC motor, I've been able to follow along and grasp just about everything about its basic electric current gives rise to magnetic field in the coil, how the stationary magnetic field in which the coil is placed produces a force (torque) perpendicular to both the wire and the direction of current. I also understand that if it weren't for the commutator, the rotor (coil) would reverse itself. Hence the need for a commutator to reverse the direction of the current and continue the revolution of the coil.

But where I'm stuck is: How does the commutator switch the current flow at the right time? How does it "know"? What is the reason for the slip-rings being split? I havent' been able to find a good explanation i can understand of exactly how a commutator does its job of reversing current flow?

Thank you, in anticipation of your help,


BTW, I have some photos to show of some projects that I'm working on. Would like them to show up in the posts. Is that allowed?