Horse box issues air not building? Help?

[hikari]

So i have a iveco 7.5t eurro cargo and i took it for a drive and half way the air stopped building up? ?? It was fine until i went on a dusty gravel track.... Could dust and got in? Anyone know how to check?

 

[The Fuzzy Furry]

Were the dials showing the pressure had built up before you got moving?
Are they now dropping or stuck?
Yr post is a bit confusing, as the air is usually allowed to build up to a safe level before moving off.

 

[turnbuckle]

Is the air right down or just not building as high as it should be?

Could be many things, whatever please take it to a garage soonest. Air brakes fail to safety (ie lock on) but even that can be bloody dangerous on a busy road.

Brakes are not to be taken lightly!

 

[Mike007]

Firstly, these brakes are air over hydraulic and DO NOT FAIL TO SAFE (ON) .They just fail. Only the handbrake will work. The air to the compressor is taken from the engine inlet manifold and is therefore filtered. There is a valve which directs air from the compressor to the various air tanks .Its job is to NOT send air to a tank that has fallen below a certain pressure unless the other tanks it supplies are above a certain pressure .The logic being that the low tank may have a burst pipe so sending its full output there would let the pressure fall in the rest of the system ,to a critical level. These valves do occasionally stick. If the truck is parked somewhere safe ,work the handbrake until there is no air left.The handbrake will now lock on. Now pump the footbrake till there is no airleft.Start the engine and leave it to tick over for ten minutes . You may well find that all is back to normal. It could be just the heat that has temporarily stuck the valve.

 

[hikari]

Sorry my post is a little confusing ill try to un confuse it . The air built up before i drove off as normal and was staying up at the normal top range then on the way back stopped building so evertime the break was used there was getting less and less air in the tanks. I made it back but now the park break is on it wont release because there is not enough air. There is no leak as the air didn't reduce when stood only when breaks are used. I released all the air from the tanks now for a test but air is still not building up.
It was find until that gravel track so thats why i wondered if it possible for dust to block the air?
I can't drive it to a garage as the park break is on plus no air no breaks!

 

[Toby_Zaphod]

I think you'll have to bite the bullet & call in a mechanic to take a look. When I ever had slight issues with air I did as you have done, knocked the air out of the tanks, let all the water vapour & crap blow out & then restarted the engine & the tanks refilled to the usual level & off I went. If that isn't happening you'll need a mechanic to check the system. Good Luck, I hope it's not too expensive.

 

[Mike007]

It does rather sound like the compressor is up the creek or the main pipe from it . You wont hear the escape of air as a hiss because it wont get enough pressure to do this. I think you need to find a mobile horsebox mechanic. What area are you. Also ,does your cab tilt or have access panels ?Compared with actual brake problems a duff compressor or main pipe is on the cheap side, even the diverter valve is relatively cheap.