Back in the mid 70's I had the opportunity or misfortune to drive one of the "H" series large truck. If you all remember it was a "C" cab jacked up on the frame to handle a Cummings diesel, this one had a 250 without turbo and a 10 speed Road Ranger. A single axle tractor. We called it a "2 Story Falcon" I don't remember what year it was but it was a scary truck to drive. The steering was like a motorboat, all over the place, and it was a gutless wonder. We only hauled containers with it the kind that go on ships.
The scariest time on when I hauled a container from a little berg in the California Valley it was a skinny 2 lane road that was slightly downhill. I started to have air pressure problems as I was coming to the freeway over crossing the air pressure blew out and the brakes locked up at only 20 mph so it slid to a stop. I popped the parking brake but the valve was ineffective so I turned off the tractor protection valve to the trailer brakes and the air pressure started to build back up and the buzzer quit sounding. I jumped out of the cab and walked to the rear of the trailer listening for air leaks and didn't hear any. When I got back the trailer bogies I knelt down and stuck my head between the wheels then all of a sudden a big hiss of air and the brakes released and I got my head from between the tires just in time as the truck started to roll forward since it was over the crest of the overpass and all downhill. I must have looked like the roadrunner being chased by the coyote as I ran like crazy trying to catch up with the cab. I was able to grab one of the grab handles on the cab and dragged myself up and inside. Full air and no brakes. I flipped the tractor protection valve with no effect and no parking brake either. The truck was picking up speed with a long straight road. I spotted a large open flat field to the right so I swung the rig to the right into the big flat field and the truck came to a stop. Still had air pressure but absolutely no brakes.
Fortunately after a while a local CHP came buy and wanted to know why I was parked in the farmers field so I explained the situation and he had his dispatcher call our office and they sent out a mechanic.
When the mechanic arrived he checked out the air system and found some kind of valve blew out and caused all those problems. He saved the day and got me going.
In hindsight I think I should have let that truck roll down the hill and destroy itself as it was a real piece of junk.