Frozen (rusted?) brakes

[Branden]

Hi all,

I've been a horrible, bad, no-good person and left my bus undriven for six months. I did start it several times and let it run for a while each time but I know the lack of driving is a sin.

My penance may be that it now doesn't want to move. I can start it and when I shift into gear I can hear and feel the transmission engage. But no movement. With rocking it back and forth from 1st to R, I seem to have freed one rear wheel, which is now able to spin. The other doesn't move.

I suspect my brakes have rusted and the air pressure is not a force that can break it. I recall hearing about being able to knock the brakes/wheel and free it up so the vehicle can be driven, the use of the brakes would then abrade them clean. Can this be done?

Thanks,
Branden

[somewhereinusa]

First CHOCK THE WHEELS so it can't move. With air pressure up and park knob pushed in (released), crawl under it and hit the offending brake shoes with a hammer. Unless it still has the dust covers on it which is rare, you should be able to see the shoes. The rust should take care of itself with use.

[Branden]

I think I generally understand the brake system and the shoes...I'm just wondering about sensitivity and adjustment. How hard am I hitting the shoes (generally speaking, MMMV)--just a tap or a good whack? is this something that would affect the brake adjustment? It occurs to me I could just try a tap, then hit it harder if that didn't work, but I don't want to hit it so hard as to damage it--is this a concern, or am I just being overly cautious?

Thanks a bunch for the suggestion!

Branden

[Brad_SwiftFur]

I had this happen once, when I was still a rookie driver and smoked the brakes going down a hill. I had to do the same thing to free the brakes (I set them while hot), and had to beat on the shoes pretty good. Eventually some help with a chisel got the offending brake free.

It might also be a good idea to check and make sure the brake chamber is actually releasing (it will probably be hissing air if it's not, a sign of a ruptured diaphragm in it).

[MrDaveG]

I wouldn't worry about hitting it too hard...I'm assuming we are talking about air drum brakes. As it has been said, figure out which one is the problem (which you have) so that your efforts can be concentrated on the one that is stuck. If you look at your brake shoes (the metal part that the lining/friction material is riveted onto) you will see that one end of the shoe is "anchored" to the brake spider (usually with a couple of springs) and the other end of the shoe is on the S-cam end, with a larger (return) spring pulling the two shoes together. Concentrate your efforts on the S-cam end of the brake shoe-that is usually the end will "move" more than any other portion of the brake shoe.
You will not affect the "adjustment", and even if you do....air brakes need to be adjusted constantly-either by the operator, mechanic or with the ABA (automatic brake adjuster) or ASA (automatic slack adjuster).
The air pressure does not force the brake to release, the air pressure (in the case of spring parking brake) only compresses a big-ass spring in the springbrake chamber, and it is the return spring between the two shoes metioned earlier that actually returns the brake shoes into the S-cam.

Clear?

[Rameses]

You can also use a pry bar between the drum and the steel backing plate of the shoe (which should stick out the side of the friction material a bit). Just try not to hit the friction material with the bar so as not to damage the braking surface.

As was said earlier, chock the wheels and take the parking brake off first.

If you don't take the brake off first, nothing you do is going to break the pads loose. If you don't chock the wheels, the bus is free to roll as soon as the pads break loose.