I noticed that Graziano does not show back EMF suppression diodes on the 24VDC relays, contactors and electromagnetic clutches on their electrical schematic. Back EMF could be the issue with the early demise of the gear box pressure switch and the arcing noted by some of the time delay relay. I have worked with 24V DC relays before and have seen using an oscilloscope several hundred volts generated when switching even a small 24VDC relay. An easy fix for the back EMF issue is to put a diode across the 24V DC inductive relays, contactors and electromagnetic clutches. A good explanation of back EMF generated by DC switching of inductive loads can be found here: http://www.eao.com/global/en/Downloa...tive-Loads.pdf
Don
Don
