I'm rebuilding a 2nd-hand mountain bike.

Taking apart the front hub I found it a bit puzzling.
It has a "Voodoo" logo on it, but that's also the name on the frame, so it may just be an OEM.
The skewer is Shimano branded.

Took it apart and replaced the bearings okay.

The unusual thing to me is the outside nut and a "shroud" attached to it. (3rd & 4th images, Voodoo3.jpg, Voodoo4.jpg.)




The nut is a normal looking steel locknut. But it's embedded into a rigid plastic cone with an aluminium shell.
I would expect to see some spacers and the locknut and a soft rubbery conical dustcap. That's what's on the rear, Shimano, hub.

If I tighten the nut up, the shroud is jammed onto the shell and the hub is immobilised.
It seems that I should set it so there is a small gap between the inner face and the hub shell.
But there is nothing to secure it, the nut can rotate and move easily.

When the wheel is inserted in the fork and the QR engaged the nut should not be mobile, but I feel uneasy about this.
If the nut does rotate the wheel could lock up suddenly, or come loose in the forks.

Is anyone familiar with this style of hub, am I doing it right?
I'm sure I didn't lose any parts, it looks all reassembled as it was when I got it.
Any online references?