6x6 Air brake line routing help

[mauinate]

I'm stuck. I have an a1 1088 (6x6 5 ton) and we moved the air tanks for the overland build. I'm in the process of reinstalling the lines to the tanks. Most were marked but some are not... and its been a while. ugh. The air over hydraulic has been removed. I've been looking through the TMs, but I can't make much sense of them, and I'm not 100% sure I even have the correct ones. I'm looking for a diagram, like the one attached, so that I can ensure the lines are correct. I've got good access to the frame and components, and I can follow the lines, but I lack the understanding of the system to really figure it out. Can anyone help please? Thanks so much!

 

[B-Dog]

I'd argue that there are errors in the diagram in the TM. You can find the diagram at the back of any of the manuals, right after the electrical. You can find some hose numbers and other info in the air troubleshooting manual, starting on page 1223, TM-9-2320-366-20-2. There are charts that show the hose/tube numbers and where they connect at each end starting on page 827 in TM-9-2320-366-20-5.

Also check here, I made my own diagram.

M1083 (6x6) A0 - Pneumatic P&ID / Schematic

Hey all, FYI, there is approx 450ft of tubing and 125 fittings for the air system including the CTIS, not including the rubber hoses to/from the hubs. In a quest to replace all the tubing in my truck, I needed to trace out all the lines. After much frustration trying to decode the P&ID in...

www.steelsoldiers.com

If you have specific hoses that you can't track down, post some clues here.

 

[mauinate]

I'd argue that there are errors in the diagram in the TM. You can find the diagram at the back of any of the manuals, right after the electrical. You can find some hose numbers and other info in the air troubleshooting manual, starting on page 1223, TM-9-2320-366-20-2. There are charts that show the hose/tube numbers and where they connect at each end starting on page 827 in TM-9-2320-366-20-5.

Also check here, I made my own diagram.

M1083 (6x6) A0 - Pneumatic P&ID / Schematic

Hey all, FYI, there is approx 450ft of tubing and 125 fittings for the air system including the CTIS, not including the rubber hoses to/from the hubs. In a quest to replace all the tubing in my truck, I needed to trace out all the lines. After much frustration trying to decode the P&ID in...

www.steelsoldiers.com

If you have specific hoses that you can't track down, post some clues here.

Thank you so much! I can’t even describe how helpful that is. I had a very productive day today thanks to you! I really appreciate the help. Your diagram is amazing.

 

[B-Dog]

Thank you so much! I can’t even describe how helpful that is. I had a very productive day today thanks to you! I really appreciate the help. Your diagram is amazing.

I'm glad to hear it!

 

[mauinate]

So dumb question:
There is a valve (I think) attached to the wet tank that feeds the Air over Hydraulic and some other valve on the very back on the passenger rear frame crossmember. I think it is a pressure protection valve. Can you guys help me understand what it does any why? And what it attaches to in the rear? Photos attached for clarity. Thank you!

 

[Mullaney]

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The valve on the tank is your Pressure Protection Valve. If you lose air in the tanks on the other side of the valve or airlines attached to those other tanks - you have enough air to stop before the spring brakes force the truck to stop.

Good way to know if it is working is when the air doesn't seem to build completely and your air operated devices in the cab like air wipers or air horn do not work. Anything considered non-essential will be disabled including CTIS and a fan clutch if you happen to have those too.

Link to a replacement part:

314107013

www.haldex.com

Simple rubber disc inside has been known to roll over and die. Rebuild parts are sometimes available on the cheap. Normal setting is 85psi.

 

[Ronmar]

The wet tank feeds: The pri and sec brake tanks, and the governor pressure sense. Via the protection valve Mullaney mentioned, it feeds cab suspension, ctis and fan control. The AOP gets its air from a 2way and a remote control valve off of the pri and sec tanks(disables AOP if park brake is released).

not sure what would be fed at the rear by wet tank. Can you get a closeup of that valve on the crossmember?

 

[mauinate]

The wet tank feeds: The pri and sec brake tanks, and the governor pressure sense. Via the protection valve Mullaney mentioned, it feeds cab suspension, ctis and fan control. The AOP gets its air from a 2way and a remote control valve off of the pri and sec tanks(disables AOP if park brake is released).

not sure what would be fed at the rear by wet tank. Can you get a closeup of that valve on the crossmember?

AOP is that air over hydraulic?

 

[Ronmar]

AOP is that air over hydraulic?

Yes air operated pump…

 

[mauinate]

AOP is that air over hydraulic?

Ok after a second set of eyes and hands, the air line that goes to the rear appears to have come from the air over hydraulic panel. Attached is a close up photo of the valve. Thank you!

 

[mauinate]

Oh, and since the aop has been removed, where should that line connect to?

 

[Mullaney]

Oh, and since the aop has been removed, where should that line connect to?

.
Follow the line back to the source, remove the plastic connector and plug it. No need to have a piece of "life giving air line" hanging around doing nothing...

 

[mauinate]

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Follow the line back to the source, remove the plastic connector and plug it. No need to have a piece of "life giving air line" hanging around doing nothing...

Sorry, the source seemed to be the selection box with the aop... it’s a 3/8” line running from the pass side (no compression connector) to that thing on the rear... I believe it came from this port on the selector box.

 

[Ronmar]

Ok that valve in the back looks like the remote control valve for the AOP. If that upper line runs to the hydraulic control then I would expect the lower line to be connected to park air somewhere back there. When park air is applied, no air will come out that upper port.

The large port on the relay(anti-compounding valve?) it is screwed into is a feed thru port. The port on the opposite side if you follow tgat line back will either connect to the primary tank or a two way that is connected to both pri/sec tanks.

On my 1079A0 that remote valve and the 2way that connects to pri/sec is at the secondary tank…

if you don't have the AOP anymore you can remove that valve and cap the port on the relay. Then follow the lower line back to where it comes from. It is probably Td off another line and you can remove that line, and replace the T with an elbow…. The upper line you can remove back to the hydraulic control…

this looks like yet another way of doing the same thing by connecting to different parts of the system. This way looks like it eliminates a 2way check from the way mine was plumbed though…

 

[mauinate]

That makes sense. Its really interesting how it seems like there are a lot of differences in the truck vs the schematics. I know mine has been through a few owners, the tractor stuff has all been removed, etc. Your guys' input and explanations have really helped me understand the system a lot more, and its starting to make sense Hopefully I'll have it all plumbed and running this week. Thanks!

 

[Mullaney]

That makes sense. Its really interesting how it seems like there are a lot of differences in the truck vs the schematics. I know mine has been through a few owners, the tractor stuff has all been removed, etc. Your guys' input and explanations have really helped me understand the system a lot more, and its starting to make sense Hopefully I'll have it all plumbed and running this week. Thanks!

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The absolute MOST DIFFICULT thing about air lines is "following the flow". Ya know how it is...
Air is invisible and trying to figure out what is "air in" and what is "air out" just isn't obvious.

Sounds like @Ronmar got you squared away with a good answer. Never hesitate to plug off something that is just hanging out doing nothing. BE SURE that if you replace a black plastic line (or red, or blue, or yellow) always use DOT Approved hoses. Safety First, especially if you are into the air system on your truck!

Make use of that phone that is strapped to your hip when you attempt to do something that isn't obvious. Snap pictures because a picture won't forget exactly how it was before you changed it. Especially if you have to "put it back the way it was"...