Someone on another forum asked how the Tru-Lok on the JK works.
This is what I posted. Thought some people here might be interested, too.
Reference the picture below.
The Electromagnet causes the Moveable Dog Clutch to engage the square teeth on the side gear.
This locks the side gear to the differential case, making the side gear turn only with the case.
This makes the spider gears unable to spin on their pins.
Since the spider gears can not spin, they drag the other side gear around with the case.
In the JK Tru-Lock differential, there are 4 spider gears, not just two as pictured.
End result: Both axles have to spin with the differential case, all as one unit.