Air Brake Pressurize Time?

[Booyah45828]

You should build full pressure in a handful of minutes. If you've gone 20-30 without pressure showing you have a pretty large leak somewhere. It should be easy to find, crawl around the tanks/hoses and drier and see if you can find air movement. If you find none, remove the hose from the compressor to the drier at the drier and see if you have air flow out of that.

To release the brakes, it normally requires a minimum of 60 psi. But that's irrelevant, because if you can't get more then that, you have leaks that need to be addressed. There's a leakdown spec for air systems, and it's 5psi leaked per 2 minutes. If you're above that, the bus shouldn't be driven.

If you can't build any pressure, I'd bet good money you're well above the leakdown spec.

 

[dj2109]

ah guys im really not sure. i fixed the leak and the pressure wont pass 90 psi or so

i cant release the parking brake!!! it just hisses!!!

 

[johnbloem1974]

If you can still hear hissing, then you have a leak somewhere. Take a sprayer with soapy water and spray it all over the airlines, fittings, and anything else related to the air system. When you see bubbles, there's your leak.

Or just find the source of the hissing sound. There's your leak.

John

 

[dj2109]

i plugged all the leaks and it will not release... tank is totally pressurized

 

[johnbloem1974]

What's your pressure? Needs to be in the 100-120 PSI range.

When you push the release valve, do you hear a rush of air? If not, the valve may be bad.

How long has it been since the brakes have been operational? Could the brakes have frozen up?

 

[dj2109]

yes im gettin over 100 psi now

when i push release is constantly hisses air until i pull again

i tried hitting drums with hammer... didnt work

 

[s2mikon]

What everyone just stated: use soap and water and look. I have had a CDL since before they were called CDL’s almost 50 years. I was also a CA state licensed class A lamp, brake and smog inspector. If a truck got a ticket for out of compliance brakes someone like me would have to put it back to spec. I used a Hudson sprayer and dawn dish soap to look for air leaks. Most of the time it was the drain valves or the new at the time water ejectors. These things receive all the water and other crap in the system and cause the valves to not close properly. When air ride became more popular the level valves became the main leak points. It is a valve that takes a lot of abuse bouncing down the road. Excessive leaks ruin air compressors. So get it fixed. One word of caution that I didn’t see mentioned is if it has air ride DO NOT get under it unless you have safety stands under the frame. If that bus falls on you, your loved ones will know the meaning of “thrown under the bus” you will be flatter than a girl scout cookie in a walmart parking lot. I’m not trying to be an ass, but if you don’t understand thoroughly how air brakes work you need to park that darn thing and learn before you drive it again. Your safety and everyone else on the road is dependent on you knowing. Driving these skoolie / coach conversions is serious business and I see a lot of posts on here that illustrates a severe lack of knowledge and a flippant attitude toward safety in general. This is also true of the other RV forums online but not as bad as here. There are also some very well informed members here too. As much as I dislike government regulations I am beginning to think that a training class and CDL should be required to drive one of these buses, but that opens up another can of worms.

 

[johnbloem1974]

yes im gettin over 100 psi now

when i push release is constantly hisses air until i pull again

i tried hitting drums with hammer... didnt work

when you push the release valve, where is the hissing coming from? If there is a leak downstream of the valve, you won't know it until you push the release and fill that section of the system...

 

[dj2109]

hissing comes from back of knob

i broke a piece off my alternate air tank.... how to fix misthreaded female?

 

[dj2109]

i got the tap and die kit and rethreaded. no more leaks. will not disengage parking brake... any ideas?

 

[s2mikon]

How much air pressure in both tanks?

 

[dj2109]

it tops at 120 psi both it seems

 

[s2mikon]

Do you have door interlocks?

 

[Rwnielsen]

Do you have door interlocks?

Do they interrupt the parking brakes too? Just curious. It's a complex and intrusive system.

 

[o1marc]

it tops at 120 psi both it seems

Go to the UserCP and fill out your profile with your location and bus info.It'll help with your issues.

 

[Booyah45828]

Do they interrupt the parking brakes too? Just curious. It's a complex and intrusive system.

Yes. If a handicap lift door is open, not only will it apply the front brakes, but it will also disable releasing the spring brakes.

 

[dj2109]

i got the leaks plugged. starts up fine. air brake releases. i switch into drive. engine revs. no MPH. no movement.... thoughts?

 

[dj2109]

hey if theres any desiel mechanics willing to talk on the phone, my wife and i were supposed to leave 2 days ago. we are really desperate. our bus just wont move. please god someone help

 

[rossvtaylor]

It does indeed sound like an interlock issue is preventing movement of the bus because it thinks something is open/not safe/a kid's sleeping in back...something.

I'll ask again, because it seems relevant and will help us with direction...please. What were you doing or working on before this happened?

 

[Mountain Gnome]

As much as I dislike government regulations I am beginning to think that a training class and CDL should be required to drive one of these buses, but that opens up another can of worms.

Sorry to hijack....


IMO, government needs only to exist for two reasons: building infrastructure like roads and bridges, and to make sure people "play fair" and "don't hurt each-other", and that means being responsible, among other things.


If I want to drink a bottle of Tequila or shoot some heroin, that is my business. If I want to drive on that stuff, that is the government's business. If someone wants to sell that stuff to me, that is our business. If someone wants to sell me moldy weed sprayed with pesticide, that is our business. If they neglect to tell me it is a hazard, or lie and tell me it is premium fresh organic, then that is the government's business.


By the same token, I think every one who drives any vehicle should have to take classes and pass a real driving test like in Germany, not a "drive down this empty 2-lane, swerve/snake around these 5 cones, and parallel park it" test. The mass of idiots I've seen in Atlanta, Miami, Chicago, LA! OMG! And more on the highways in-between!



(p.s. And please don't consume alcohol or heroin. that stuff sucks. But it is your business if you do.)