Texas CDL General Knowledge Practice Exam 2025 – 400 Free Practice Questions to Pass the Exam

The purpose of the air brake system is to slow down or stop the vehicle. Air brakes use compressed air to apply pressure to the brake pads or shoes, which then create friction against the brake drums or discs, ultimately decelerating the vehicle. This system is especially crucial in large commercial vehicles, such as trucks and buses, where the vehicle's weight and size make effective braking systems vital for safety. Unlike hydraulic brake systems, air brakes allow for greater force to be applied, making them more effective in stopping heavy vehicles.

The other options relate to functions that are not part of the air brake system's design or purpose. For example, enhancing traction on slippery roads involves different systems, such as traction control or advanced tire technology, while controlling engine temperature falls under cooling systems. Steering assistance is typically managed by power steering, not the braking system. Understanding the specific function of air brakes is essential for safe operation and compliance with regulations concerning commercial driving.