When sliding tandems, why does air pressure have to be at 120+ before pulling red valve?

Ive actually made it so impossible to not know that if you are actually tracing where air flows from that i have to beleive you're actually a troll at this point.

Heres your hint, look at the first diagram, its color coded, follow the colors

 

It looks to me like the answer is that when there is air in the red line, the air flow does not go to the tandem pins. And when there is no air in the red line, the air flow goes to the tandem pins. Is that correct?

 

No. It look at your diagram A. It does NOT show where the air is coming from.

You're making these assumptions that I know things that I don't definitely know.

 

Using the diagram you drew at the top of the page, it looks to me like the air flow in diagram A is from the tractor to the air tank.

 

In post #26, you say what you were ultimately shooting for when you took the time to draw the diagram. I made post #32 to ask you if I seem to have the gist of what you were shooting for. Could you respond to my post #32 please?

 

Im making the assumption that you can read a labeled and color coded diagram and have working knowledge that your red line on the tractor is what supplies air to your tractor.

That is genuinely it. diagram a is simply more detailed diagram 2 and for that matter a more detailed view of the top diagram.

Theres so little creative thinking needed here that i have to guess you have never built anything from a print. Thats something im just not able to deal with in a grown adult.

 

Correct

And while i dont have post numbers turned on or mobile just doesnt show em.

The only extrapolation you need is this, in diagram a, air is flowing from tractor to
i. Release brakes
ii. Get air to tank
iii. Prevent the tandem valve from being operated.

All of the above are happening at the same time when your tech came out and found when you pushed your brake pedal you had air come out your red line.

That simply isnt supposed to happen

 

I just asked to confirm. I wanted to be 100% sure.

 

I'm not a construction worker or a builder.

Why won't you tell me if what I wrote in post #32 is correct? You took the trouble to make that diagram. You told me your purpose in making the diagram was to try to teach me why having air in my red line caused me difficulty in sliding the tandems. Well, you could make your drawing that diagram not be in vain if you would just address post 32

 

skallagrime does not seem to want to work with me any further on this. If anyone else who is reading this is knowledgeable about this stuff, I invite them to comment on what I wrote in post #32.