Brakes do not release

[m-35tom]

OK, front service glad hand has a vent on the cover and I know it is stuck closed. When using brakes they will not release unless the cover is removed. Is this normal and is the check valve vent the only problem? Why is there pressure there at all?
Tom

 

[Ronmar]

yes, its normal. both the front glad hands need to be vented. What happens is a little air leaks past the 2way check valves into the service glad hand line when you step on the brakes. If it is capped, that line then becomes a storage "tank". When you let off the pedal, that storage now becomes an air source. It flips the two way check and supplies the output which is the service brakes, keeping them engaged at that pressure, until enough air leaks off to release the brakes...

 

[m-35tom]

OK, thanks Ron, this truck sat for a year and had many lines ripped off when it crashed. I will just replace that vent.

 

[Ronmar]

If you get a lot of air leaking out of the front, then you have a bad 2way check...

 

[m-35tom]

OK, with the service side open everything works normally, didn't even notice any air until I put the 2 glad hands on and plumbed them back up with covers in place.