When descending hills, what should be primarily used to help slow down the apparatus?

Using both the engine and auxiliary brakes while descending hills is essential for controlling the speed of the apparatus effectively. The engine braking helps reduce speed without overheating the brakes, which can occur if they are used alone for extended periods. By engaging the engine brake, you utilize the vehicle's own powertrain to slow the vehicle down, providing a more gradual decrease in speed.

Auxiliary brakes, such as exhaust brakes or compression brakes, assist by providing additional braking force. These systems can significantly enhance braking efficiency on long descents, helping to maintain a safe and controlled speed without relying solely on the conventional brake system.

The combination of both engine and auxiliary brakes allows for a safer descent, minimizes wear on the main brake system, and enhances overall vehicle control. This approach is particularly important in fire service operations, where quick response and safety are paramount while navigating various terrains.