Practice question

What happens if the red emergency supply line between tractor and trailer ruptures or disconnects during highway driving?

The trailer accelerates away from the tractor
The trailer's emergency relay valve senses rapid pressure loss and instantly applies full pneumatic braking to the trailer wheels
The tractor engine shuts down immediately
Nothing happens until the driver presses the footbrake

Answer: B — The trailer's emergency relay valve senses rapid pressure loss and instantly applies full pneumatic braking to the trailer wheels

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