bryanx,

Your front driveaxles have a set of splines that "float" with the hub unlocked. This means that they freewheel like the front hub of a 2WD vehicle. In autolocking hubs, when torque is applied to the front drive assembly, pressure is applied to a spring and a gear in the hub slides inward to engage the drive axle, locking the hub to the axle. Auto locking hubs can take a foot or so to engage due to the mechanics of it. Manual locking hubs do the same thing, minus the springs and extra distance needed to engage. When the manual hub lever is turned, it pushes the gear in mechanically and engages the front axle splines. The engagement is immediate. I think if you can picture this, you should have a solid grasp of how they work and what happens when they do.

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Gordon "The Warmonger" White