They are and this is how they work, but... they don't seem to do a very good job of keeping the brakes adjusted snug as they should be..

I manually adjust my brakes (using the brake star wheel) then the handbrake pulls tight where it should...

I also recommend not touching the handbrake cable adjustment unless you first properly adjust the brakes themselves using the starwheel adjustment and only then (if needed) mess with the parking brake cable adjustment...

One caveat.. if you are not familar with the starwheel adjuster and where the self adjuster makes contact with it, you might want to pull the brake drum off and look at it closely.. shown below


As with many self adjusting brakes you can turn the starwheel in the direction to tighten up the brake shoes, but you need to stick a second screwdriver in the slot to lift the self adjuster off the starwheel before you can turn it backwards if you need to loosen the adjustment.. It's easy once you get the hang of it..