When should a driver in a commercial vehicle use the engine brake?

Using the engine brake is particularly important when descending a steep grade because it helps control the vehicle's speed without relying solely on the service brakes. In a commercial vehicle, which is often heavier than standard vehicles, maintaining a safe speed while going downhill is critical to prevent brake overheating, which can lead to brake failure.

The engine brake works by redirecting the engine's compression to slow down the vehicle, allowing drivers to manage speed effectively. This technique is essential for preventing runaway conditions often experienced when a heavy truck descends a hill. It helps maintain safer control, reduces wear on the conventional braking system, and ultimately promotes safer driving practices in braking scenarios.

In contrast, using the engine brake on flat surfaces is generally unnecessary as the vehicle is typically under control and does not require additional deceleration from the engine. Accelerating typically requires the application of power rather than deceleration, and stopping at traffic lights usually involves using the service brakes to bring the vehicle to a complete stop rather than relying on the engine braking alone. Thus, understanding the proper use of the engine brake is crucial for safety in specific driving conditions, particularly when dealing with gradients.