Sean, I have not had time to look for the "excess flow" valve, but I will do that in the next few days.
I have not yet implemented a breakaway system yet. Jack Conrad and another person have been giving me guidance on how to do that.
Basically, Jack uses a system the mimics the M&G system. That is to use a typical trailer breakaway switch that operates a solenoid valve. I have been looking for a suitable pressure reservoir. One person suggested using PVC. Not sure I feel comfortable with that material. I do have a copper tubing accumulator that I built for another application that I will probably use.
The system seems pretty simple. Air in to a pressure chamber via a one way valve, air out the the brake cylinder via a solenoid activated by the breakaway switch. I have to think my way through how to deal with stopping the flow back out the broken application line. I think that can be done with another check valve. Jack has given me that information, but I have not studied it in detail.
Jack charges his pressure cylinder via the air from the brake supply line. He hits the brakes with full application and that charges the cylinder. I am a bit concerned about that process on my application, as you need to bleed the vacuum out of the toad brakes before you make the full pressure application. Otherwise, you could overload the the master cylinder. That is not an issue with the M&G system since it is between the vacuum chamber and the master cylinder.
When we get ready to depart, I have my wife apply the brakes a few times while I check the toad. When I get the breakaway plumbed in, I will have her do several light applications while I do my checking (to bleed the vacuum) and then I will do a couple of full applications before I depart.
At least that is the plan
Jack, my apologies to you. I probably butchered you "system", but I know you will straighten me out
. I think there is a thread on this specific subject, but I did not do a search.
zubzub, what you are describing is what is typically called a surge brake system. It is used on tag type trailers (and I think one dolly manufacturer uses it). The tongue is free to float and activate a master cylinder if the towing vehicle slows down. The only ones I have seen are a "closed" hydraulic system contained withing the trailer. I am not sure how you could make that concept work with a air system or withing the hydraulic system of the toad. You would definitely not want to try to plumb it into the toad hydraulic system!!!
Many folks do not like trailers with surge brakes because they activate when you are trying to back the trailer. That would probably not be an issue with a bus/toad, since you really should not try to back them up (exception very slow short distances).