You're driving an articulated lorry that has 3 air lines connected to the trailer. What's the purpose of the red line?

You're driving an articulated lorry that has 3 air lines connected to the trailer. What's the purpose of the red line?

It's the emergency line

Correct answer

DVSA explanation

The red emergency line is common to both two-line and three-line brake systems. The other colours are blue (for the auxiliary line) and yellow (for the service line).

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