In a two-line braking system, what is the effect of a rupture in the emergency line to the trailer?

In German traffic regulations, a two-line braking system on a trailer consists of a service line and an emergency line. The emergency line serves as a safety feature: if it ruptures or is damaged, it triggers the trailer's brakes automatically to prevent a runaway situation. This is why option 1 is correct—the trailer brakes when the emergency line fails.

Additionally, the emergency line is sealed off upon rupture to prevent air loss and maintain braking function, which corresponds to option 2. The truck's own brakes are not automatically activated by the emergency line rupture, so option 3 does not apply.

Understanding this system is important for safe trailer operation, as it ensures the trailer will stop safely if the emergency air supply fails.