
454 LIGHT AND HEAVY VEHICLE TECHNOLOGY
lines between tractive units and their semi-trailers. The
quick release end couplings for the hoses may be of the
earlier male and female bayonet type or the later
internationally used palm type, these also being known
aptly as gladhand couplings in America because of their
resemblance to clasped hands. Automatic shut-off valves
may be incorporated in both types of coupling, so that
air pressure is retained when the feed line to the trailer
reservoir is disconnected. The end couplings of the
hoses are designed so that they cannot be wrongly
connected and the hoses themselves are colour coded
for ready