What type of fluid is used in hydraulic braking systems?

Hydraulic braking systems rely on a specific type of fluid known as brake fluid to operate effectively. Brake fluid is specially formulated to withstand high temperatures and maintain consistent viscosity and compressibility under various conditions, ensuring that the force applied to the brake pedal is transmitted efficiently to the brake calipers. This fluid is also designed to be non-compressible so that it can transfer the force applied by the driver directly to the braking mechanism without any loss of pressure, which is critical for effective braking performance.

Furthermore, brake fluid has a high boiling point to prevent vaporization under intense heat generated during braking, which could lead to brake failure. It is also hygroscopic, meaning it absorbs moisture over time, which can affect its boiling point and braking performance; therefore, regular maintenance and replacement of brake fluid are essential to ensure safety and reliability in braking systems.

In contrast, engine oil is designed for lubrication, transmission fluid is optimized for gear shifting and cooling in automatic transmissions, and coolant is used primarily for engine temperature regulation. Each of these fluids has different chemical compositions and properties that do not align with the critical requirements of hydraulic braking systems, underscoring the importance of using dedicated brake fluid for this application.