BC Transit – Air Brake Course

Emergency Functions
The following slides will walk you through the functions of the tractortrailer
braking system when things go wrong. For example:
•The trailer could break away from the tractor if, for example, the king
pin or fifth wheel failed.
•A sudden air loss due to a rupture of the supply line will cause the
trailer to “dynamite.”
•A rupture to the service line would render the trailer brakes
inoperative.
•The supply and service lines could be inadvertently connected
incorrectly (crossed)
•Some of these scenarios could be corrected by the operator (glad
hands simply came apart). Others, would require the services of a
mechanic.
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