Thank you

Your still getting air to the chamber to release the parking brakes (red lines), but when you put your foot on the brake pedal that chamber doesnt do anything, because you blocked the (blue) line to stop the leak.

I'm like yourself. I need to know how something works if I'm going to remember anything lol

 

It looks like it was the service line coming out of the triple valve to just one brake chamber, that means the other 3 brakes would work normally and your plug would simply keep air from escaping from the disabled line at too fast a rate.

I carry 4 male and 4 female pipe plugs that can be bought at any hardware store, 1 each of 1/8, 1/4, 3/8 and 1/2 just for this reason; that costs about 5 dollars for all eight but if this happens you can just plug the supply right at the triple valve and remove the bad line.

If this had occurred on the red line to the same brake chamber you would have had to cage the maxi chamber to move the trailer after plugging the line, the red line releases the brake so if it is plugged off that brake won't release when you push the trailer release valve. The blue line applies the brake when you step on the brake pedal so if it is plugged you just lose the service of that one brake when you step on the pedal.

That is why the brake has two chambers, 1 houses a powerful spring that applies the brake when there is no pressure to pull the spring back and the other is just an air chamber that fills when you step on the brake and pushes the rod to apply the brake.