Parking brake release issues

[Geo.Lander]

Hi, my truck has been sitting now for a couple of weeks, there was still air in the system and it fires up to 8 bar really quickly. All the other neumatic systems seem to work fine but the parking brake won't release. No sound coming from it at all when engagement and disengaged..
There has been freezing rain and cold temperatures lately.. any ideas? I'm sort of stuck.

 

[DiploStrat]

There is a knob with the ((P)) logo on the console/engine cover. Don’t really know what it does, but try turning it.

 

[Geo.Lander]

Fixed, thanks!

 

[Neil]

I would start with the release valve itself. this is located under the cab floor on the back of the release lever.

It could be that this valve simply isn't releasing, Maybe through wear and tear or recent frost damage.

Before your do anything please ensure that the vehicle wheels are chocked and in gear ( Engine off ) and it cannot move, because if that brake comes off unexpectedly the vehicle could start to roll

1. Get the Pressure up .
2. Release the lever
3. Tip the cab
4. Start giving the valve mechanism a good sharp tap .
5. If this doesn't release then move backwards along the line doing the same to every valve on the way.

Another option is one of the valves in the 4 way safety valve is stuck.

This is usually located near the air tanks. its usually a way valve filling up your air circuits in the correct order. One of the last to fill will be the Parking Brake, so if this valve failed it could still provide air to the foot brake circuits but not the parking Brake .

Again take the appropriate safety precautions and give each valve a good tap.

If you can identify which of the 4 valves is the parking break you could crack the union on it a very small amount to see of its open and providing pressure This valve should look something like this

Good luck and please secure the vehicle first

Neil

 

[Neil]

Just refreshed and saw you fixed it. What was the issue out of interest

Neil

 

[Geo.Lander]

Just refreshed and saw you fixed it. What was the issue out of interest

Neil

Really appreciate the fast feedback, goes to show how much we still have to learn.

Basically there was no fault but my own stupidity. The ventilation and defrost value was open.. I saw almost 6 bar still in the system when I tried to release the brake. I'm not sure what the value is called in English but it was in the open position. I suppose this is a safely for low air pressure?

 

[Neil]

Glad its sorted

Neil