Practice question

What happens if the red emergency air supply line disconnects or ruptures while driving an articulated semi-trailer?

The trailer accelerates instantly
Air pressure in the trailer supply line drops to zero, causing the trailer emergency relay valve to exhaust air from the spring brake chambers and automatically apply the trailer spring brakes with full emergency stopping force
The tractor engine shuts off immediately
The vehicle steering locks completely

Answer: B — Air pressure in the trailer supply line drops to zero, causing the trailer emergency relay valve to exhaust air from the spring brake chambers and automatically apply the trailer spring brakes with full emergency stopping force

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