Cab air valve for tire inflation.

[rustystud]

Today I cleaned up one of my in cab air valves and found something interesting. There is a small hole in the handle that goes down to the valve itself. I looked up this type of valve on the internet and found out it is called a "Plug Valve" or sometimes a "Tapered Cone" valve. The reason there is a hole there is to drain out the air from the line when it is not in use. Also it can be used to "lubricate" the valve. I remember reading awhile back someone had problems with their air valve leaking after they cleaned it up. If this hole is not lined up correctly then it will leak on the pressure side. So the valve core must be aligned up correctly and also the "limiting washer" on the bottom.
Thought I would post this incase someone else is cleaning up their valves.