[rheavn]

This post is what I have found on my coach which has the HWH leveling system.  If your coach is not exactly the same, it will be similar if you have the HWH system.

I've been doing an air line schematic to complement the rear suspension schematic that I've already done.  Newell has basically set up three air systems that interrelate.  The black air system is the brake system.  The red air system is the suspension system.   The blue air system is the house air system.  The colors are designated by the color of air line that Newell used to "feed" the separate systems.

The first schematic is of the air lines of the differential lock solenoid, rear distribution block, rear air dryer and the rear six pack.  The rear distribution block is mounted on the vertical wall just forward of the right rear engine compartment.  The rest of the items are located in the right rear engine compartment.  Follow the 1/4" black air line from the "in" of the differential lock solenoid and it will take you to the distribution block. 

   

The second schematic is a "junction point" that on my coach is found on the rear wall of the left rear air spring tank.  The left rear air spring tank is the one that is the most forward & sits above the transmission cooler with the double fans.  This is where Newell chose to join the front & rear suspension air system (red), front & rear house system (blue) and the front and rear brake system (black).  Newell provided two shut off valves that allows you to shut off either the red or blue systems or both.  There is no shut off for the air brake system. 

   

The "junction point" is very difficult to get a good picture of and get all the lines in it.  These are the best I came up with.

       


To understand where the air goes we'll look at how it works by providing "shop" air to a totally drained air system on each test. 

Test #1--Turn off both shut off valves and air is provided only to all three brake system air tanks, the brake dash gauge and the 3 gallon air tank in the first compartment on the right side.  ***Not all coaches will have this 3 gallon air tank!

Test #2--Open the "red" circuit shut off valve and leave the "blue" valve closed.  Air is now provided to all three brake air tanks, the brake dash air gauge, the 3 gallon air tank in compartment R-1, the front & rear 6 packs,  and rear air dryer.

Test #3--Open the "blue" circuit shut off valve and close the "red" shut off valve.  Air is now provided to the 3 gallon air tank in R-1, all three brake air tanks, both the brake & supply dash gauges, the 3 gallon air tank in the RR wheel well and the entire 12V air compressor air system.

Test #4--Open both the "red" & "blue" shut off valves and the entire coach receives air.

Hopefully this helps you understand how your system works and how each "circuit interrelates to each other......................................

[Chester Stone]

Very good and thanks.

[77newell]

Steve: great diagram and description.

To add some additional, and hopefully useful, information based upon my 93 coach:
The device in the upper right with 2 wires, on my coach that is the switch that turns the "low air pressure" light on-off on the dash. The square just next to the switch would be the pressure protection valve that shuts off the flow of air to the non-brake uses whenever the pressure in the supply tank falls below 65psi.

The reason the the brake tanks pressurize whether the "blue" or "red" valves are open or closed is because the flow of air between the supply tank and the brake tanks runs separately and in parallel to the flows shown on the diagram.

This explains why the brake tank pressures rise from zero gradually and the supply tank gauge will rise suddenly to the brake tank pressure at about the same time the dash "low air pressure" light goes out. It isn't exactly the same time, but in the ballpark.

[RussWhite]

Steve,

I think what you called the "transmission cooler" is actually the hydraulic fluid cooler. The transmission cooler is a portion of the radiator.

Thanks for all your work and pictures !

[rheavn]

Jon,
Thank you for filling in a couple more pieces of the puzzle! Your info is very helpful.

Russ,
I can't count how many times you have corrected me that the cooler is indeed the hydraulic cooler and not the transmission cooler. My feeble mind has trouble accepting & storing the info. One of these days I'll get it.

[cfree3]

You had some great diagrams of the air system.

We want to know for sure which tank is the supply tank. That is the tank that appears to be leaking air from. The brake supply air pressure gauge does not go down.

We have two tanks in front of coach and one or two tanks in the rear of the coach.

Can you help us out with that?

[ron skeen]

You had some great diagrams of the air system.

We want to know for sure which tank is the supply tank.  That is the tank that appears to be leaking air from.  The brake supply air pressure gauge does not go down.  

We have two tanks in front of coach and one or two tanks in the rear of the coach.  

Can you help us out with that?

The two front tanks are the front and rear brake supply. The big tank in rear is the supply tank. The small tank in rear wheel well is for the air doors and commode.

---

On my 96 all the air went through the supply tank first and then to the brake tanks which were protected by one way valves.

[Fulltiming]

One my coach, the two brake tanks are in the front, directly behind and above the front axle. The supply tank (aka wet tank or Aux Tank) on my coach is located in the rear near the drive axle. All three tanks run E/W. There are one way valves on both front brake tanks to isolate them in case of a leak in the supply tank so they should be holding air as you indicated they are.

[77newell]

If you close the two valves that Steve showed you can monitor the pressure in two of the systems by checking the pressure loss shown on the dash gauge (which gets its pressure from the front distribution block) and the pressure gauge at the rear six-pack (shows pressure at both six-packs). It would be handy to have a pressure gauge added from the rear distribution block so that then all parts of the system could be separately monitored. As it stands now if you close both valves you have no way to see what is happening with the service tank and rear distribution block since they are isolated from both installed gauges. There are available ports on the rear distribution block to tap for this added gauge.

I never did figure out on my coach where the 1/4" black line going forward ends that Steve shows on his diagram.

The other curiosity with this system is why there is a drier prior to the rear six-pack but not for the front six-pack.

One other detail on my 93 coach that differs from Steve's drawing is that my rear HCVs are fed from the rear six-pack on the port opposite and in line with the air supply line.

[cfree3]

You are talking about the six-pack valves. Where exactly are they located and do you have a picture of them?

Last night our leak must have gotten worse because the air compressor was running non-stop. I finally turned off the leveling system and it appeared that finally the compressor turned off and got a break for about 10 min. before starting up again. Does this help to give you any clue on where our leak might be?

Thanks for all your help.