Most modern automobiles are equipped with disc brakes on the front wheels and drum brakes on the rear wheels. This frictional contact slows and then stops the rotation. This vise-like action slows and then stops the rotation.
Worn pads can groove rotors, causing brake noise and damage.
Excessively worn pads should be replaced. Calipers hold pads in place against the revolving rotor to stop the vehicle. Leaking calipers can damage pads and weaken the system, causing unreliable stopping. Damaged calipers should be serviced or replaced. The disc pads make frictional contact with the rotor to stop the vehicle.