Which air brake system is most commonly used in trailers?

The air brake system most commonly used in trailers is the service brake system that uses air pressure. This system is preferred for heavy-duty commercial vehicles, including trailers, because it effectively handles the substantial weight and braking demands of larger vehicles. The operation relies on compressed air to actuate the brakes, providing a powerful and reliable braking force.

Trailers equipped with air brakes allow for better modulation and control, especially under heavy loads, as the system can quickly and evenly apply braking force across multiple wheels. This is essential for maintaining stability and safety during operation. Moreover, air brake systems are designed to operate efficiently in conjunction with the tractor's braking system, ensuring effective stopping power in various driving conditions.

Other braking systems like hydraulic, disc, or vacuum brake systems are generally used in lighter vehicles or specific contexts, but they do not match the robustness and reliability required for the larger trailers typically found in commercial transportation. Thus, the choice of using a service brake system that utilizes air pressure in trailers is primarily due to its effectiveness, safety, and suitability for heavy loads.