You are driving a motor vehicle with a manual gearbox. How do you conserve the service brake when driving down a long downward slope?

To conserve the service brake while driving down a long downhill slope, it is important to use a combination of techniques that allow for effective braking without overheating the brakes.

By dropping down the gears in plenty of time, you are allowing the engine to help slow the vehicle down through engine braking. This reduces the reliance on the service brake, which can lead to brake wear and overheating.

Using the permanent brake in conjunction with engine braking provides a controlled descent. The permanent brake (typically the foot brake) should be applied lightly as needed to maintain a safe speed. This technique is in accordance with German traffic regulations that emphasize vehicle control and safety, particularly in hilly areas.

On the other hand, using the parking brake is not appropriate while driving down slopes as it is intended for securing a stationary vehicle. Engaging the parking brake during motion can lead to loss of control and is against traffic rules.

Thus, the combination of dropping down gears and utilizing the permanent brake is the correct approach to safely manage speed on a long downward slope.