Which brake system employs hydraulics to retract pads?

The caliper brake system is the correct answer because it uses hydraulic force to retract the brake pads when the brakes are released. In this type of braking system, hydraulic fluid plays a crucial role; it is pressurized within the brake lines and acts upon pistons in the brake caliper. When the brake pedal is pressed, the hydraulic pressure forces the pistons to push the brake pads against the rotor to create friction and slow down or stop the vehicle. Upon releasing the brake pedal, the hydraulics retract the pistons, which in turn pulls the pads away from the rotor, ensuring that there is minimal drag and allowing for a smooth continuation of motion.

This mechanism is central to the operation of caliper brakes, making them very effective in various applications, including in escalators where precise control over speed and stopping is essential. Other brake systems, while also effective for their specific functions, do not utilize hydraulics in the same way to retract the pads, making them distinct in their operational methodologies.