1/2” air actuated valve for train horn???

Guessing a brake relay valve would do the trick
I think 1/4 line would be plenty for actuation

 

Ball valve

 

thats what i was thinkin.

 

Your correct the brake relay will keep going until the signal is withdrawn. A typical air horn valve may or may not relieve the pressure when released. It wouldn’t have to to function but might because of the way it’s built. A small leak in the line will probably work ok to let it shut off if the horn valve doesn’t release pressure. I don’t think a foot valve will work because it’s meant to send a signal so probably not going to flow enough it will be considerably more expensive and it’s not air piloted.
Are you going to give it a dedicated tank?

 

Shouldn’t need an exhaust for the horns. The air exhausts through them. With a ball valve you can slowly crack it open to control the sound.
A trolly valve will do the same because it graduates the psi instead of just open and closed like a regular horn pull.

 

I use a 1/2” electric / air
I have a toggle on the dash instead of the grab handle on the floor or the existing rope pull
I did 1/2” line direct to the horns and got rid of all that 1/4 line

I’ll find the part and update the post

edit
Not the exact one I have but same concept
Black Widow 1/2" Electric Air Valve

 

JMO.. but this ^^^^^^^ is the cleanest and simplest way
I myself literally hate that high dollar chrome air line with a ball value mounted right beside the seat ... its something more to be in the way and make your cab look clutter.. besides that's the way all the Super truckers wanta roll and I haven't earned my Super Trucker card and flip flops yet

 

Which horns do you run, assuming you got them from there? I need something in addition to my factory horn that will make people crap their souls.