A-518 Lockup and OD question

FWIW I've looked at the PATC setup and a few others... I wish I could remember who did the design of the one I posted... He's designed what I consider the best way of controlling the RH series O/D's...

Using timers solves the shortcomings of most designs...

I did my first 518 install back in 2000 which used more parts sensors, switches, vacuum bleeds than it needs but twenty three years later it still works pretty well.. It has a few quirks that are going to cause me to swap out the current controls to the timer relay design...