replacing pressure regulator valve

[bevans6]

Well, in total sympathetic reaction to Depewtee, my bus decided  to vent air continuously at the curb side rear wheel.  It was losing 1 PSI per minute.  Looked around in there and found the parking brake pressure regulator leaking everywhere - the vent hole, all of the 1/4" bolts that hold it together, lots of leaks.  Probably been leaking a bit for some time.  Anyway, the Williams pressure regulator is still a valid part number, would this be special order these days or should I expect my local truck parts supply house to have one? If they have another PR, is it OK to interchange or must it be the Willams  WM 279-E1 piece?

Thanks, Brian

[Depewtee]

Brian,

I posted some pics of my valve in my original thread.  Is this the same valve you are having trouble with?  I am not sure what it is called.

Brian S.

[bevans6]

The valve in your picture is the R-8 valve, or the rear brake relay valve.  It is what applies and releases the air to the rear drive axle brakes (not positive about the tags, my bus doesn't have tag axles).  It has a signal line from the brake application valve up front (what the pedal works), a  main air supply line from the dry tank directly, two lines that go out to the rear brake cans, and acts as the rear quick release valve to quickly dump air from the brake cans when the pedal is released.  the bit on your valve that seems to have something missing is the quick release diaphram cover, I think.

My valve is a little 2" diameter pressure regulator that limits the air pressure to the parking brake on the DD3 rear axle to 85 PSI.

Hope this helps a bit.

Brian