Breaks on a hill can the give with no air pressure

Pull the buttons

 

Put the truck in lowest gear and turn engine off if brakes arent holding

 

you ought to get that fixed......just say'in....

 

Get off the hill and stop where it’s flat. Lol

 

If you're parked with the knobs pulled out then air pressure isn't what's holding the brakes. There's a really heavy spring in all cans except the steers that is held back by air pressure. That air is released when the knobs are. It still uses the same slack adjusters so if they're out of whack it'll still be weak. That might be an out of service ticket if you get caught. Best to get some new knobs that do pop out. They're not hugely expensive and fairly simple to change compared to a lot of things.

Oh, and it's brakes not breaks.

 

Unless there are a bunch of chambers with broken springs. Seen it happen more than once.


OP, the guys are right. Unless you're driving a truck built 60+ years ago the air holds the park brakes released. Pulling out the buttons will exhaust the air and let the springs hold the brakes applied. Brake adjustment is important as well.

 

I would suggest you have truck and trailer brakes checked by a mechanic, you have that kind of problem and get a dot inspection you’ll be paying for mobile service.
Have them check the breakaway valve also.