What type of brake system includes a component called an s-cam?

Answer: D — Air brake system

The component known as an s-cam is typically found in air brake systems. It is a crucial part of the drum brake mechanism used in many commercial vehicles. The s-cam works by rotating, which pushes the brake shoes outward against the inner surface of the drum. This action creates the friction needed to slow down or stop the vehicle. Conversely, hydraulic brake systems do not use s-cams; they rely on hydraulic fluid to transfer force. Disc brake systems, while similar in function to drum brakes, utilize calipers and rotors rather than an s-cam design. Understanding these distinctions is essential, as the s-cam's role is specific to air brake systems in commercial vehicle applications.