What must you do after coupling up a single-axle trailer with overrun brakes?

After coupling a single-axle trailer with overrun brakes, it is essential to perform a series of safety checks to ensure the trailer is secure and safe to operate on the road.

1. Checking that the brakes are working is important because it confirms that the trailer's braking system functions correctly, which is crucial for safe deceleration and stopping.

2. Raising the jack wheel, if fitted, to the highest setting is necessary to remove any ground contact that could interfere with the trailer's operation. This helps in ensuring stability while the trailer is in motion.

3. Attaching the brakeaway cable to the coupling of the motor vehicle is vital as it provides an additional safety measure. If the trailer becomes detached from the vehicle while in motion, the brakeaway system engages, applying the trailer's brakes to prevent runaway situations.

All three steps are important under German traffic regulations to ensure the safe and legal operation of a trailer, reducing the risk of accidents and enhancing overall road safety.