Originally Posted by Rogue1bus
Found the part number on the side... Itís a Pressure Protection Valve, designed to protect the air brakes from accessory failure.
Down stream of the valve are air bags on the rear axle to adjust ride height. I think Iím going to leave it off.. if the air bags failed I would just have to install a 1/4npt plug on the side of the road..
Originally Posted by cadillackid
bad move!! your air bags can fail catastrophically.. I had one Pop on my DEV bus.. it dumped air very quickly down to the protection valve pressure.. which is still above spring brake pressure... no big deal I drove the bus home, got a bag and done..
it doesnt take long wit hthe generally small tanks school busses have to dump your air out of a 1/4" line.. you blow a bag and have no protector valve you could find your rear wheels locking up as you fly down the highway.. you likely wont hear the air and if on a bouncy road not even notice right away the bag has gone flat.. the air gauges will drop quickly.. unless you are watching them like a hawk you wont notice till the alarm is beeping.. by then you are well on your way to spring-brake auto-apply...
all for a $20 part..
sorry - my take.. if it sounds harsh.. i dont like seeing people remove safety equipment..
temporarily to get home or safe, yeah thats OK. but as a permanent fix? FAIL..
Christopher knows his stuff and speaking from my own personal experience, he's right. Pop an air bag and you likely won't notice anything amiss until the low air alarm goes off - and if this sounds like the voice of personal experience talking, that's because it is. Without that valve, what would have been a minor annoying problem has now become a "FIND A GAP IN TRAFFIC SO I CAN PULL OFF RIGHT NOW" emergency. Good luck in any traffic.
Manufacturers are cheap, they won't put a valve like that on unless there was a reason for them to. It *IS* a safety, protection thing after all.