What is the main difference between open and closed systems in braking?

• A. Open systems allow air to enter; closed systems do not
• B. Open systems use more brake fluid than closed systems
• C. Open systems require more frequent maintenance
• D. Closed systems provide better braking feel

Answer: (A)

The primary distinction between open and closed systems in braking revolves around how air and fluid are managed within the system. In an open system, the design permits air to enter, which can adversely affect braking performance by introducing compressibility. This can lead to a spongy brake feel and reduced responsiveness, as well as potentially allowing moisture to enter, which can corrode components over time. In contrast, a closed system is sealed to prevent air from entering, ensuring that brake fluid remains free from contaminants and that the brake feel remains consistent and effective. This sealed environment allows for optimal pressure to be maintained within the braking circuit, enabling reliable and powerful braking performance.