Confused about stop arm/safety gate air plumbing
Hi all, my 2006 Thomas bus was retrofitted with one of those yellow front "safety gates" which pops out at the same time as the stop sign to prevent kids from crossing to close in front of the bus.
Looking at the plumbing for the stop sign and gate (see attached photo), I can't quite figure out what does what. I see the two regulators (one for the stop sign and one for the safety arm), and one solenoid. I know that the red air line goes directly to the stop sign, but the other tees have me really confused. I can't quite figure out where the air comes in; in either location, it wouldn't make sense as it would seem like one of the regulators would always have an air supply.
Ultimately I'd like to reuse one regulator and the solenoid for some other air operated accessory in the future so I'm hoping to clean this up a bit in the meantime. I am going to try harder to trace the air lines into the chassis but there's a LOT going on in that particular area and all I can really find are multiple black air lines that all look the same.
I'm hoping someone else has a similar setup and can provide some tips.
PS. I just had a thought. Could it be that the air supply comes into one regulator, out to the solenoid, then tees off directly to the front arm and the second regulator, which feeds the stop sign? This would make a little sense if the front arm required more pressure than the stop sign and/or they needed to drop the pressure before the solenoid...