Found on some Nissans and Suzukis.
If we look back at the Auto / Lock hubs these hubs are just Auto.

Key Points.

To engage, you have to STOP, engage 4wd in transfer box; with either the lever or pushing a button (whichever option you have), and when you drive off they go to the lock position.

As long as you don’t reverse they will stay locked when you go back to 2wd which means you can change back to 4wd on the fly.

If you need them to go back to free when you go back to 2wd then you have to reverse back. You will hear the click from the hubs when you do this.

You will also hear the clicks when you are in 4wd which means that the hubs have gone free and you lose the drive to the front wheels when you need it most! And because there is no override option to LOCK the hubs you are stuck with this problem.

Reminder about FWHs and what they Do /Don't Do...

First, let me dispel a few myths;

1. They do not engage 4wd - this is done in the transfer case.
2. They do not lock the front differential.

What they do, is engage and disengage the half shaft or drive shaft from the hub of the wheel. When the device is in the locked position the shaft is engaged and when in the free position it is disengaged.