Truck brakes won't lock

Never assume that a part is good or bad based on age.
I’ve pulled new lights out of the bag that were bad.

 

You should learn how to adjust your brakes. Also, brake valves can be bad right out of the box and they can fail within hours of installation due to all types of things. Take it to a shop. Nobody here can diagnose your truck from behind a keyboard.

 

Maybe the springs are broken in both 30/30 chambers. Most Freightliners only have parking brakes on 1 axle. The rear. You can usually tell if the spring is broken. Put a screwdriver into the hole on the parking chamber. Pry against the big spring. If it rattles around, it’s broken. Sometimes though, they break and still stay tight enough that you can’t tell it’s broken.

 

Everybody gave you reasonable advice.

You just refuse to listen.

 

Well what happens when you dump the air valve in the cab is that the air keeping the spring brakes from actuating is dumped, then the springs ( which are very strong ) force the brake rod to the end of there travel causing the brake shoes to be jammed against the drums. The other thing that can keep the springs from actuating is if someone installed the T-Bolts into the chambers and cranked them down or partially down, which would limit the travel of the spring. That's easy enough to check, simply look i'd there is no bolt in the middle of the maxi-canister, then that's not the issue. Next I would remove the air lines from the brake canister, if the maxi's (springs) don't engage at that point there bad., It is air pressure that keeps the spring brakes from engaging, so no air line, no air they should be locked up (the brakes). if not you could check the adjustment, but I do not think the slack adjuster can keep the maxi's from engaging. Place to check anyway. Be very careful working with the spring bake chambers they can be dangerous, lots of pressure held in that spring.

 

Hey @aceman18, you didn't let us know the resolution here. Surely you have fixed the issue by now.

Don't like crow?........

 

So it WAS a brake valve after all lol.