Maxi brake Chambers have 2 sides, each side can act on the brake rod. If you are flooring the brakes and you pop the park knob, you're trying to use both sides of the brake chamber to hold the truck. You may not hear a hissy from the park brake engaging because of this.
Have you had situations when trying to set the brakes where they didn't actually set and the truck started rolling?
Having a similar issue on ch713 '06 . Having parking brake set pressing brake allows spring to release. Also during start up when building air pressure brakes will release until 80psi
2006 Granite parking brakes won't set
in Modern Mack Truck General Discussion
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Having a similar issue on ch713 '06 . Having parking brake set pressing brake allows spring to release. Also during start up when building air pressure brakes will release until 80psi