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You are correct Jon, air from the foot valve goes to the service port of the relay valve which causes application of tank pressure via the delivery port to the spring brake assembly. There is no air to the service side of the brake chamber if the pedal is not depressed - then it is applied in a corresponding amount with the distance pedal of travel.Quote:
Originally Posted by Jon Wehrenberg
Here is a picture of how the AFO integrates with the coach.
The air going back to the towed vehicle is NOT the air from the Prevost brakes. The air from the Prevost brakes controls how much air is past from the "New Air Reserve Tank" to the "Towed Vehicle" in the above diagram. If the area between the "New Air Reserve Tank" and the "New Relay Valve" is compromised, air will be able to escape from the coach's reserve tank. That is where the "New Pressure Protection Valve" comes in. When the pressure drops in the "Existing Primary Air Reserve" to ~80-90 psi., the "New Pressure Protection Valve" closes, allowing the breach to be contained, and the coach's brakes to operate safely. Since the air pressure in the "Existing Primary Air Reserve" is lower than where the coach wants it, the compressor builds more air. Any air above the pressure protection valve's minimum limit is allowed through (to atmosphere in this case). This is where the sound of "air" would be coming from, and why the coach was still able to operate safely.
As long as a system leakage or failure is downstream from the new pressure protection valve life is good. If it is between the valve and the supply from the primary air reservoir life sucks. A critical portion of the installation would be to provide maximum protection for the Tee and the protection valve.
Thanks for the response. It makes sense now and what you have created is a miniature air brake system that functions exactly like the bus system.
Hi Jon and Pete,Quote:
Originally Posted by Jon Wehrenberg
I forgot to ask one question about my Toad Brake failure. When the (AFO) valve broke away from the (AFO) tank, what if anything should of happened to the brake system on the Toad? I did not notice anything, felt no braking action saw no lights go on, and assumed now that the failure simply disables the Toad brake?
You got it. I might also add the bus has pressure protection valves littered throughout to isolate components in the event of a coach-related failure.Quote:
Originally Posted by Jon Wehrenberg
I'm a little slow sometimes. But now that I get it I appreciate it more.
Good job.
What happened in your case was the "Signal Air For New Relay Valve" was still "telling" the the valve to allow x psi to the towed vehicle; however, there was no air available to go back to the towed because the supply was severed. The end result was no braking effort.Quote:
Originally Posted by 0533
Pete,
I was following this discussion with interest. Being from the far coast I wasn't able to make it to the rally in TN. I hope that you will be at a future POG rally, as I'd like to get a system on my coach as well.
I appreciate how much time you have spent here, answering questions, and supporting our group.
I hope we'll get the chance to do business here in the future!
Ray
Pete made arrangements for our brake system to be examined by John Bleakely in Atlanta and they said everything was fine. They also replaced the LEDs on the Toad and they work fine now.
Thanks Pete, great job and great service. We can recommend SMI highly. They have all be quite responsive.