Air valve help....

I say I need help with and air “valve” but I’m not sure that is exactly View attachment 224983 View attachment 224984 View attachment 224985 View attachment 224984 how I should refer to it. I have a valve that is leaking on my Volvo VHD 10 wheeler, it’s a Wabco and I have numbers but the parts house wants me to bring it in but I don’t have time to take it off, go in, find out they don’t have it, blah, blah, blah....I’ll post some pics, if anyone can point me in some kind of direction that...

Air valve help....