The pressure may fall everywhere at the same time as in the sprinkler example, but the pressure on the end of the crank (#6 rod bearing) is lower to begin with, right? It dips below what is required to keep the rod end coming into contact with the bearing, and *boom*. All it takes is a little dip in pressure and the one(s) with the lowest is/are at risk.
That's my 'uneducated' stab at it.
-Lance
