Autoslacks have been required by law here since 1997 on OTR trucks and 1998 on trailers. Most auto slacks do not require any manual adjustment beyond full service brake applications, with the exception of ; a new installation (initial adjustment), or during brake reline/disassembly. In fact, many auto slacks can be damaged by regular manual adjusts if they use a one-way clutch mechanism. If an auto slack is found to be "out of adjustment" with no obvious damage, it should be re-adjusted and tested for proper operation before replacement, as the slack may have been previously misadjusted.

out of adjustment..
 

"They are self adjusting", once stated that to a DOT inspector, I was a nubee. :oops:

And...Do your brake system pressure check, brake pedal mashed to the floor while you watch the gages and listen for air leaks. Being easy on the brakes I did not do the check 8) . When a car cut me off and stopped short I realized :shock: SOMETHING WAS WRONG...a blown diaphragm. It very well would have shown up in the system pressure check, had I done it.