[Richard]

Well……..

We had another incident of the hot brakes coming down I 17 from Flagstaff into Tom’s Resort. This time, the first thing I did was jack up each front tire and check to see if the brakes were dragging. They were not. Hmmmmm. Conclusion being, something else is going on. I noticed both the drive drums and tag discs were not even warm, meaning all the braking was being done by the fronts. I wasn’t in a great place to do any more looking, the coach stopped just fine, and I decided to proceed although gearing down on the jakes to reduce my brake useage even more. The temps came down quickly, and we had no more problems. 

While at Tom’s, I lay awake at night thinking of all the things it could be, and how to check each one. 

Turned out, it was very simple. The picture is of a brass coupling in the pilot line from the brake pedal to the brake relay valve in the rear. It is cracked through and through. The impact of that crack is it reduced the signal pressure from the brake pedal to both the drive and tag brakes. I had Rhonda apply the brakes while I was under the rear, and immediately heard the air leak.
   

I had a gauge inserted into the M&G brake line to measure actual brake line pressure. With the crack, I got no more than 60 psi, after the repair the brake line pressure was at 90.


I have added the apply the brakes and listen for leaks to my safety check list.