How does the air dryer on your semi truck come apart?

There are several different models of air dryers out there... make and model of your truck doesn't really help, because, while brands will have a brand they offer as standard (e.g., Kenworth and Peterbilt come standard with Bendix, Freightliner and Western Star come standard with Wabco-Meritor as standard, etc.), they can be ordered with either system per customer specifications.