[Lynn Eades]

Darrin, Somewhere back home, I have info on this.
The early british carriers had a pipe that went over to the tool board (an open breather that was supposed to act as an air lock when fording. This was I believe continued in The early Aussie and Kiwi built Aussie pattern carriers. They were later modified to a plug which had a brass grease fitting screwed into it. This would have held pressure in the axle (but would have better kept the water out)