Why are Bendix self adjusters - the ones with a screw-jack, toothed wheel and little metal spring such utter utter crap?
The teeth on the wheel wear out, the little leaf springs break, the screw-jack jams.
Dire.
Best self adjusters I ever saw was simple. A spring rather like the shoe hold-down spring only much bigger stopped the shoes moving back under the pull-off springs. The free movement needed to release the shoes came from the gripping springs having a bit of slop in their holes. Magic.