Sometimes air brake on international grab and dont release.

I have a 89 model international 9400 series tractor truck that is converted to a dump truck. Sometimes (10 % chance) when I really hit the brakes they grab and don't let go when I take my foot off. I either have to tap the pedal or wait until they release on there own. This happened to me while backing a load up a hill a week ago and the brakes grabbed and I was slow letting out the clutch. It killed the engine and the steering wheel spun out of my hand and caught my thumb. Broke my...

Sometimes air brake on international grab and dont release.

Sometimes air brake on international grab and dont release.