Interesting. 5 pages of posts, but only 2 or 3 that address the air pressure issue.
It just may be all about SAFETY! As noted in one post, the rig will not move until the air pressure gets to about 60 PSI to unlock the spring brakes. The rig will not stop without 60 PSI or more air pressure.
That little engine mounted compressor doesn't pump air very fast. The minimum pressure to release the spring brakes doesn't allow for very many service brake applications, and if the pressure drops below the minimum, the spring brakes will lock up again.
Personally, I would prefer that the driver wait until he has the full 120 PSI for his brakes. The safety is worth the noise.
BUT, please, do not go around and open all the air moisture dump valves. Do that later.
Oh, and for the complainers, be glad that diesel doesn't have an air starter. THAT is a loud noise!
