Split ring communtator

[Umesh]

ive been going through the nelson and henimen book but i am seriously lost when it comes to how a split ring commutator works, i know how a slip ring one does, has anyone got a good explaination, if not does anyone know a good internet site? I didnt really understand the "how stuff works" explaination for it

[cara.mel]

The general principle is that after each half rotation, the brushes connect with the other side of the battery. This means that with respect to the armature (the bit of wire inside the magnetic field that rotates), the current flows the opposite way, but with respect to the whole circuit, the current still flows the same way. This means that the force on each side of the wire relative to the magnets etc is always in the same direction, and hence it keeps spinning.

I drew a picture, tried to install scanner but got some vista error so I just took photos with webcam so apologies for bad quality
http://img.photobucket.com/albums/v711/happypuff/130627.jpg
http://img.photobucket.com/albums/v711/happypuff/130531.jpg

Tell me if you need more explaining (:

Also, you should understand this for the end of year exam as you might have to explain how it works

[Umesh]

The general principle is that after each half rotation, the brushes connect with the other side of the battery. This means that with respect to the armature (the bit of wire inside the magnetic field that rotates), the current flows the opposite way, but with respect to the whole circuit, the current still flows the same way. This means that the force on each side of the wire relative to the magnets etc is always in the same direction, and hence it keeps spinning.

I drew a picture, need to install scanner driver then will upload it

thanks so much! so its quite similar to reversing the ends of a battery