It's for step-less aperture operation, not AF
One motor (left) for normal stepping aperture in 1/3 stop increments, one motor (right) for smooth step-less aperture change.
More of a video recording gadget than still image.
Are we generally to dismiss things you have to say as pure conjecture disguised as certainty or do you know something contrary to the above information? Such a trait in life is only a hindrance to yourself and everyone around you who doesn't know to be more dismissive of you, consider doing that less, perhaps?
The reason I say this is that the last bullet point clearly states one motor is to assist another with acceleration... and I apologise for being an ass to you but people have buttons, just like cameras do, and this kind of insistent tripe disguised as informed fact pushes mine in the context of people trying to gain an education and understanding.
But yeah, I'm a little surprised the CR folk didn't clock the word "Aperture" or recognise anything from the diagramme as aperture control hardware.
jrista and pin008 sound like they're barking up the right tree! Now I've to obsessively research these terms I don't know already; Canon EMD aperture? DCM motors?...
Also, if anyone's curious and isn't familiar with the design it appears that 7a are pins which the aperture blades pivot around and slot into 3b. 7b are little pins attached to the blades, these rest in 6a. Parts 3 & 7 rotate, 6 remains static and the blades open and close as the pins 7b travel along slots 6a.
I've aaalso just noticed the motors operate different cogs, 3a & 4A, hence their varying axel length (is 'axel' correct here?)
I'm wondering if 4 is perhaps relatively loose, offering enough friction to add to the acceleration but not so much as to be in conflict with the precision offered by the other motor?