What are these hoses?

They dont go through the manifold in the firewall I think. I followed at least one of them (the silver one) to the dash valve. Ordered a service kit (o-rings etc) and will try to install that... I suspect the dash valve because whenever I release the tractor brake the hissing doesnt stop abruptly as it should (?), instead it keeps hissing for at least a second.

Thanks! So grab a plumbing wrench or something and block the air hoses to each brake chamber until I have determined whether blocking one of them eliminates the problem? Sorry for all the beginner questions and thanks for all the useful help!