Double wheels on back of van

Yes, on a twin wheeler they are drum brakes, on a single axle twin wheel set up the shoe is about four inches wide and the hubs have longer studs.the inner wheel is fitted the normal way and the outer is back to front so to speak.

 

What's a "hub brake" ?
I've heard of inboard (where the disc brake system is nearer the differential than the wheel)
I've heard of disc brakes (vented ones too)
I've heard of drum brakes (even on the front axle)
But I can't say I've ever heard of hub brakes
The "hub" should be the centre part where the wheel bearings (tapered, rollered etc.) revolve around the end of the axle, at the centre of the wheel, I'm almost certain of that.
Can someone educate me please?

 

Hub brake or drum brake, just a different name for the same thing.

 

Thanks PTS. It must be my age I must be too young to of heard of hub brakes