Brakes won't release??

[Jerry W Campbell]

Hello Friends,
I haven't been around for a while, I've been busy with the "Doctors".
I haven't driven the bus in a year and a half. 1975 Crown. Today I fired her up and the brakes would not release. The brake peddle is as hard as a rock. The air system sounds Like it's supposed to when I release the parking brake but the front brakes don't release. Don't know about the rear.
I was told all the brakes and associated air parts were new when I bought the bus 18 years ago. I found out that was true when I blew an air line and had to crawl around under the bus on a bridge in southern Mexico. I've driven her south almost every year since and I've never had to do anything except adjust the slack adjusters so I know nothing about the air brake system. The rods in the air chambers don't move. It seems like they should??
Any help would be appreciated.
Thanks
Jerry

[Utahclaimjumper]

In the year and one half that it has sat,, no doubt the rear brakes were set in the "on" position.. When this happens ,, they can rust in that position over a length of time and will have to be freed up.. Many times just a hammer will do it,, other times a disassembly will be required.>>>Dan

[Bill Gerrie]

Sometimes rocking the bus in drive and then reverse will free a stuck brake. If the fronts are not even moving then you will probably have to do a complete repair to release them.

[buswarrior]

The brake pedal description, "hard as a rock"?

Is the pedal moving?

If it isn't, hang on, that's a specific problem with the pedal.

Otherwise:

The various valves can stick, mud daubers can plug up the vent side of everything, linings can rust to drums.

Cycling over and over, apply engine power in both forward and reverse, concurrently, as it leans into it, stab hard, full brake as it leans in either direction, wait for the air to build back up, repeat, repeat, repeat.

Get a picture in your mind of that rusty interface and what it will take to tear it loose. Lean, push, squeeze, lean, etc

I am wickedly lazy, and promote the same: don't go under there until you have spent a lot of time in the driver's seat, trying to get it torn loose on its own.

Happy coaching!
Buswarrior

[chessie4905]

Does the pedal attach to the brake directly or does it connect through linkage that may have rusted fast at the pivot point,s?

[Jerry W Campbell]

Thanks for the replies,
The brake pedal is all the way to the top and does not move. I think I will fix that and then go from there. Hopefully just a dirt dauber plugging a vent.
Thanks so much getting me started, I'll let you know what happens.
Jerry

[bevans6]

a big question would be how is the pedal connected to the treadle valve?  I kind of suspect a linkage failure, either in the levers or the pedal, depending on how it's connected to the treadle valve, because it kind of sounds like it's stuck in a full pressure application.  Parking brake will do nothing to the front wheels, only the drive axle.  What parking  brake does a Crown have, could be spring brakes?

[Jerry W Campbell]

I don't know what kind of parking brake is on my Crown. It does sound like it's stuck in a full pressure application.
I don't know what a treadle valve is either. The brake pedal is hooked to an air valve directly under the floor, which is connected to a quick release valve between the two front brakes. There is no linkage. I have not looked at the rear. Both front brakes are locked up so I am assuming the problem is either the brake pedal valve or the quick release valve.
Jerry

PS:   I checked the rear and they work correctly

[chessie4905]

Make sure the pin the treadle or pedal pivots from isn't  rusted fast or something managed to get under it.

[Jerry W Campbell]

YAHOOOO, They all work,  I drained the air and started the bus, I banged and hammered, I took off the parking brake, when it reached 120 I jerked back and forth a couple of times and hit the brake pedal a couple of times hard and she rolled free. One more thing off my list before winter comes and it's time to hit the road.
I appreciate you all being here
Thanks
Jerry

[buswarrior]

A little Driver's Seat Justice...

Lovely progress!

Happy coaching!
Buswarrior

[chessie4905]

Brake pedal is hard as a rock??? Apparently it worked as normal, but nothing happened???

[bevans6]

So you're going to call it good, and do no more inspection, preventive maintenance on your air brakes before you drive off into the sunset? 

[Jerry W Campbell]

I have had the bus serviced every trip south for the last 15 years.
Normally I like it when problems fix themselves. Having had an air system failure, I vow not to let that happen again. I have a logger buddy who is coming over when he gets the chance to try to help me figure out why the front brakes froze. Hopefully it was just a valve that was a little sticky. I've got a couple of months to figure it out.
Thanks
Jerry

So you're going to call it good, and do no more inspection, preventive maintenance on your air brakes before you drive off into the sunset?