no tractor parking brakes?

Take it to a shop. Don't try to fix your brakes if you don't know what you're doing. For our sakes and yours.

 

I agree with windsmith on this. It's not only safer using a qualified shop, it'll be cheaper in the long run if you're just going to throw parts at it. Changing brake chambers is fairly simple, but also easy to do wrong if you don't know how to get the right rod length and set the slack adjusters up right. They can also do some serious bodily harm, spring brakes can have about 1500 lbs of spring force, not something that you want hitting you in the face.

That being said, do you hear air release when you pull the brakes on? If not, then you definitely have an air issue. If you do hear the normal air release, then it's more likely a mechanical problem. Keep us informed and we can help make sure that the shop is honest with you. How many air lines were on each of those chambers that you changed on the rear axle? Many trucks only have 2 spring brake chambers (2 air lines on each chamber). On the other axle they are only service chambers (1 air line per chamber) and are not supposed to move when you set the parking brakes. Your problem could be as simple as needing 2 chambers and you just changed the wrong 2. If that's the case, it's more likely that you have been running on 1 parking brake for a while and just now noticed because the 2nd one just broke, very rare for 2 spring to break at the same time.

 

more than likely the valve supplying air to the chambers, if no air getting there , they wont work.

 

maybe you adjusted them the wrong way. some slack adjusters do that. specially manuals. but i've seen autos that were bad and would go the wrong way.

can you see the brakes moveing as your adjusting them????? preferably TOWARDS the drum and not AWAY fron the drum.

seems weird that NONE would do their job with the valve pulled.

the few times i've had that problem. was cured with a simple adjustment on all 4. and keep adjusting till the shop replaces them.

 

As the guys said before, be very careful on this one.
you should crawl under there and see if your S-cams are extended out to the tips.
Same happened to me years ago, the pads we're wore down so low S cams where about to "Cam over". Not sure if that's still possible on trucks now days. Just a thought, you don't want to go for that ride!!! Be careful, let us know.