What occurs after the driver applies the brake pedal?

When the driver applies the brake pedal, the primary and secondary pistons move forward. This action is integral to the brake system's functionality, particularly in hydraulic brake systems. When the brake pedal is pressed, it activates the master cylinder, which generates hydraulic pressure. This pressure causes the primary piston to push fluid into the brake lines, effectively moving the pistons within the brake calipers or wheel cylinders forward. As a result, this movement engages the brake pads against the brake rotors or drums, slowing or stopping the vehicle.

In hydraulic systems, the forward motion of the pistons ensures that the necessary force is applied to create friction between the brake components, leading to effective braking. This mechanism is crucial for controlling the vehicle's speed and ensuring safety while driving.