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Old 10-03-2012, 07:42 AM   #1
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Air Brake Help

Ok got the bus out of storage, brakes were definitely froze. I would press them and the bus would come to a jarring halt and throw you out of the seat almost. Got it home and lubed up the brake components to best of ability. Took it out for a spin and it is a lot better, but when you press the pedal, about half the time it stays activated and will not release brakes (unless you mash it real hard to release them). Took the main valve off of the firewall in engine compartment (the one that sends air either in or out to chamber) hoping thats the problem.

Any other thoughts?


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Old 10-03-2012, 10:53 AM   #2
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Re: Air Brake Help

If you did what I think you did, you have activated your brakes. You need air pressure to release your brakes. You can't think of air brakes like hydraulic brakes on your car. When you step on the brake, you are releasing pressure which applies the shoes. I would have your brakes checked out by a mechanic that understands air brakes, not you local mechanic. You might also read up an air brake manual in the DMV commercial driver handbook to give you an overview of the brake system.
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Old 10-03-2012, 01:45 PM   #3
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Re: Air Brake Help

Oops. Maybe I should be doing the reading. I think I'll watch the video.
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Old 10-26-2012, 02:18 PM   #4
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Re: Air Brake Help

Sounds like the service brake valve (the one from the brake pedal) may be sticking open. Think of the air system like a water faucet. There is water going to a faucet all the time, but unless you turn it on, no water. The air system works the same way. Air pressure is always there on one side of the system, but none on the other until you press the pedal. The only two ways to deliver air to the brakes is to open the service brake valve by steeping on the pedal, or releasing the PP1 valve (Spring Brake) to set the rear brakes. You mentioned you took the main valve off to check, and that is the most likely source of the problem. It has a diaphram inside, and if not closing properly, could be your problem. Its sounds like your looking in the right place.
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