Parking valve doesn't pop up

[it_mike]

My manual copy is handily missing that page, it starts chapter 4 at page 4-3.  I always wondered what was on page one and two...

I've been using the online manuals, I'll have to see if they're missing those pages.

[thomasinnv]

My manual copy is handily missing that page, it starts chapter 4 at page 4-3.  I always wondered what was on page one and two...

I've been using the online manuals, I'll have to see if they're missing those pages.

is that online manual only for the 9, or is there one for the 8?

[it_mike]

Sorry, only mc9

[it_mike]

In a DD3, the trouble is, the parking control valve is supplied by the isolated parking tank, which doesn't have a gauge to show you what's going on.

You can't get the parking control to pop on a DD3 without the parking tank pressure dropping far enough

OK, now I'm confused again. If I use pumping action on the brake pedal to drop the main system pressure, will this cause my valve to pop-up?  Brian,  are yours DD3 or spring brakes?

[BG6]

I guess if I kept fanning the brakes, engine off, then eventually I would have lowered the pressure in the parking brake tank enough for the spring to activate the push/pull valve.

It doesn't matter -- he was using the wrong procedure, watching for the pop-up at a particular gauge reading.  Your gauge and tank system aren't set up to match the procedure, and most examiners really don't know anything that isn't in their manuals.  Some schools, truck and bus companies specifically ask for the good ones by name when setting up an inspection, and will even send their trucks from one end of the state to the other for inspections because it's cheaper for them to go all that way than to have trucks fail inspections that they should have passed.

[bevans6]

On your bus and my bus, both with DD3 systems of similar vintage, the P/P valve handle will ONLY pop up on it's own when the pressure in BOTH the dry service tank and the parking brake tank are below 40 psi simultaneously.  If EITHER is above 40 psi, it will not pop up automatically.

You probably could do it by fanning the brake pedal, but there is a lot going on there, what with the inversion valve switching things and the shuttle valve switching between the dry service tank and the parking brake tank.  I know that I fanned my brakes down to 10 psi on the gauge and it did not pop up, because I still had pressure in the parking brake tank at that point. 

Brian

[buswarrior]

And remember, it is the Inspector's responsibility to have his/her proper procedures in order.

How did they inspect all the older coaches?

Get your tie rod fixed and back you politely go!

happy coaching!
buswarrior

[Tony LEE]

If you think you have problems with inspectors not using the correct procedures, you should try owning an MCI in Australia where DD3 brakes are just about unheard of. Every year I have to get out the manual and go through the system with the inspectors - otherwise I WILL get a defect because they only know about normal spring brakes