djusting the Bendix D2 governor just takes a 7/16 wrench and a screwdriver. The unloading pressure for the typical air brake system is 120 psi but it can be higher up to 130 psi without a problem. Anywhere in the middle is good in my book. This is an easy adjustment as you can see in the video.
The adjustment is touchy and to increase unloading pressure you turn the screw clockwise and counter clockwise to reduce pressure. When the air breake valve compressor reaches it’s limit the governor is there to unload it preventing air pressure from building too high. For you seasoned mechanics this is very elementary information but for those who didn’t know how to make this adjustment then I hope this info helps.