Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

From the top of the pipe to the top of the shaft (knob off) about 1.25~1.26 inches.  I am not sure what "catches" it from coming out but I don't think it is anything from the bottom of the shaft.  Has to be some other kind of a "catch" but what it is a mystery to me!  Perhaps at some point someone else will figure out how to unscrew the pipes from the center, without fudging up the finish!  Getting them a part is a mystery to me.