BIGWIG74:
im having problems with a slow releasing hand brake on a 06 cf85 8x4 ive changed the 4 way valve/air processing and the relay valve under the nearside step.its ok once it does release just taking a few moments more than our other trucks,if anyone has any ideas it would be appreciated
You have a spring brake on axle 2 and 4 …You changed the 4 way protetion valve because that was a common fault for slow release of the handbrake as there is NRV in the port thinks it port 25 …im getting old and the memory is failing …Working on the premise that the braking system has been checked and the caliper are ok ,and no leaks in the system and the other vehicles that releas quicker are also DAFs of about the same age …
.To release the handbrake you require air …So you need gauge /gauges to see how long it takes the pressure to build up to release the brakes
You have system pressure to a relay valve ,that gets a signal from the handbrake which passes through a 2 way valve ,never known the 2 way valve be an issue …So check the air pressure at the relay valve ,you should have system pressure ,if so then what is coming out of port 2s again it should be system pressure ,after that it is the spring brakes…
A small tip remove the silencer from the Load Sensing Valve ,if that can’t exhaust quickly it will hold the footbrake side on and give the sympton of a slow to release handbrake
Lastly you have plumbed the APU up correctly with the handbrake to Port 25 ■■?