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Newell Gurus
Air brake system - Printable Version

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+--- Thread: Air brake system (/showthread.php?tid=2718)

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RE: Air brake system - Richard - 10-11-2016

Thanks for the clarity. Follow the line from the drive axle brake can up into the belly and it will end
at the brake relay valve. There should be a plugged port on that valve that you can use.

RE: Air brake system - rooster - 10-11-2016

Thank You Richard.  I removed the plug from the valve, it appears to be a 1/2 inch NPT plug.  Air poured out so I figured I had the wrong relay.  Pulled the plug from the other, which I am quite sure is the spring brake relay, and again air came out in great volume.  It would seem that I need a source that would not be under pressure until service brake is applied, so I am stumped.  I will try to get a picture posted.  pk

RE: Air brake system - Richard - 10-11-2016

Ok, if you pull the plug from the SUPPLY side you will get air.

Look on that valve for more ports. They should only be under pressure when the service brake is supplied.

Now, if all that is futile. Can you detach the brake supply line at the can? If so you should be able to use brass NPT fittings to install a tee. Of course, use DOT fittings for the tubing.

You really only have three choices. Tap in at the relay. Cut the tubing and insert a tee. Insert a tee between the tubing and the brake can.

RE: Air brake system - rooster - 10-12-2016

Thanks Richard. I will go over today and have another look at things. I am working on tow light wiring. It had the old commercial truck tow plug, and there was no stop light power. I tapped into one of the taillight wires and ran it down to the right rear electrical compartment. I will install the brake converter box in there and run a new cable to the Tow Socket installed in the bumper. I have blue ox add on lights on the Jeep. I had the air fitting on the Bluebird installed at the factory at delivery, so I never had to install the air supply before. Appreciate your advise. Pete

RE: Air brake system - Richard - 10-12-2016

Hmmm, after looking at the diagram of the relay valve http://www.anythingtruck.com/product/061-103009X.html and looking under my coach, I have a better appreciation for your situation.

There are only two delivery ports on the relay valve. The unused port that was plugged is just the opposite side of the supply port.

And Newell used heavy duty hose to connect the relay valve to the brake cannister.

I would try to disconnect the hose fitting from the cannister and put the tee at that point.

RE: Air brake system - Richard - 10-12-2016

I am still trying to help, and I hope I am not hurting.

I went under the coach to refresh my memory on EXACTLY what I did. In my defense, I'm forgetful, I've done this on two Newells, and no two Newells are alike.

First this is what I did. You can see the pic of the tee. The part that I didn't remember is that I tapped into the 3/8 line that comes out of the relay valve and goes to the antilock valve. A ha! That was the missing piece in my memory. So if you have antilock, you are in business.     

But if you don't, here is a picture of where the brake line goes into the cannister. If yours is anything like mine, you could unscrew the male fitting from the cannister, use a short nipple, and a brass tee. You would need a DOT fitting for the M&G connection to the Tee.     

I hope this is clearer than mud.

RE: Air brake system - 77newell - 10-12-2016

Richard: a question, why put the tee at the cannister rather than at the relay valve. I am wondering if the placement at the cannister could cause a slight delay in brake actuation on that side as air fills the cannisters. Given the small air volume of the braking system in the car I doubt it would be a problem but if there is a problem then having the tee closer to the midpoint of the system should virtually eliminate it. If you are installing a tee for the first time, unless there are other reasons such as available space, why noT put it near the relay. Also the relay is stationary and the cannister gets shaken, not stirred, .....

Given your well thought out suggestions, I'm wondering what I'm missing in my own thinking.

RE: Air brake system - Richard - 10-12-2016

Jon, only reason for putting the tee at the can was accessibility.

RE: Air brake system - rooster - 10-12-2016

Thanks Guys.  My 88 coach does not have anti lock.  I like the idea of teeing at the relay valve because it eliminates the movement of the axle and makes routing the 1/4 inch M&G line much easier.  I am doing some doctoring this week but hope to get over to the coach tomorrow and look things over again.   Appreciate all the advise.  Just rebuilt the slide valve solenoid for the step cover and got that working.  It was leaking air badly.  Now detect air leak at front six pack.  Gotta get some bubble stuff to pinpoint it.  Always little chores to keep things tip-top.  Next will be mounting my Train Horn beneath the left front.  Pete

RE: Air brake system - 77newell - 10-12-2016

Let us know if that horn rattles the headlights loose Smile