What is one correct function of retarders in a commercial vehicle?

The function of retarders in a commercial vehicle is primarily to help slow the vehicle. Retarders provide additional braking power, especially when descending grades, by using different methods—such as engine compression or hydraulic systems—to create a force that slows down the vehicle without relying solely on the traditional brake system. This function is particularly important in maintaining control and reducing the risk of brake fade, which can occur when the brakes are overused and become less effective due to heat buildup.

By engaging a retarder, the driver can lessen the wear on the service brakes, improving overall safety and longevity of the brake components. This assists in maintaining a safe speed while going downhill or in situations that require reduced speed without overusing the braking system. Retarders are effective at managing vehicle speed, which is why they are considered a vital component in the braking system of heavy commercial vehicles.