Just won an auction - M1088A1

Ronmar said:

I guess that would depend on which line it is

Click to expand...

It must be the one from the remote control valve, since the AOH pump is gone and the air springs work when I depress the knob on the manifold

I'm thinking that I should cap the line from the remote control valve, until I can delete it

I'm learning a little about pneumatic switches. The "P" port is Pressure Inlet. The "A" port is Pressure Out. The "R" port is Pressure Release.

I'm guessing that one of the 1/8" lines is Pressure In and the other is Pressure Release. Now how to sort out which one is which? Absent better advice, I'll hook them up and see if it works. If it doesn't, I'll reverse it.

dwlindsey said:

I'm learning a little about pneumatic switches. The "P" port is Pressure Inlet. The "A" port is Pressure Out. The "R" port is Pressure Release.

I'm guessing that one of the 1/8" lines is Pressure In and the other is Pressure Release. Now how to sort out which one is which? Absent better advice, I'll hook them up and see if it works. If it doesn't, I'll reverse it.

Click to expand...

Well if you start the truck, as soon as the wet tank exceeds ~85PSI, the supply line will start to flow air...

For cab suspension, one of the lines is supply pressure from the wet tank, the other line is out to the cab suspension height control valve. The R port Vent is on the back of the hydraulic control valve module and does not have a line attached to it...

Think of the cab valve like a single pole double throw switch that switches a common connector between two other connectors. Supply pressure comes in on one of the two switchable connections(P), the load/cab suspension is on the common connection(A) and the second switchable connection is the vent or release port(R).

A switches between P and R. When you switch the valve to the P port, pressure flows in thru p and out the common port A to feed the load, and the ride height valve uses this pressure to inflate or deflate the bags to control height. When you switch the A from P to R, this seals the P port and connects the A port to the R port, and any air in the cab suspension flows back and vents to atmosphere thru the R port... In my picture you can just see a sintered bronze filter in the R port where the air vents out when deflating the system. this is to keep debris and insects out of that port...

Ronmar said:

Think of the cab valve like a single pole double throw switch that switches a common connector between two other connectors. Supply pressure comes in on one of the two switchable connections(P), the load/cab suspension is on the common connection(A) and the second switchable connection is the vent or release port(R).

Click to expand...

Ronmar said:

Well if you start the truck, as soon as the wet tank exceeds ~85PSI, the supply line will start to flow air...

For cab suspension, one of the lines is supply pressure from the wet tank, the other line is out to the cab suspension height control valve. The R port Vent is on the back of the hydraulic control valve module and does not have a line attached to it...

Think of the cab valve like a single pole double throw switch that switches a common connector between two other connectors. Supply pressure comes in on one of the two switchable connections(P), the load/cab suspension is on the common connection(A) and the second switchable connection is the vent or release port(R).

Click to expand...

I think the missing 4th air hose from the manifold is the hose that went to the AOH Pump, which is now completely naked without hydraulic or air hose attached. I disconnected that several weeks ago, so memory faded, but that must be the one that's gone.

So I'm thinking that the 1/4 inch tube going into the mainifold must be the supply. I'll put that in port P. Then one of the two remaining 1/8 inch tubes will be the air springs. I'll put one of them in port A. And if the air bags don't inflate, then I have the wrong 1/8 inch tube connected and I'll change it.

I'm missing one fitting, which should arrive tomorrow, so I'll hook up the new valve tomorrow.

Small progress today. One of the air fittings hasn't arrived, so I worked on removing the AOH pump and the spare tire lift. One bolt removed from the spare tire lift, 4 bolts removed holding the AOH pump. All 5 bolts very annoying to remove, difficult to get the wrench on the nuts. But a little progress.

I may need to back the truck out of the garage to get at the remaining bolts on the spare tire lift, I think at least one of them will require tilting the cab up and I can't do that in the garage. That's for another day.

Now I'm starting to think about the hatch on the cab. Most of the bolts are halfway in . . . so removing them will be easier . . . Then, I believe I'll clean the surfaces, thread the bolts barely in and have a 3 props, small wooden props, maybe pieces of 1x2 or a couple of paint sticks, holding the hatch off the roof while I apply Sikaflex 252. Then one at a time, remove the props and fill in 252. Then turn in the bolts tightly and clean up with Sika remover 208.

That should be waterproof, but after it cures, I'll do another bead of caulking.

Sound OK? Better suggestions?