Final answer:
The s-cam in s-cam brakes is a component that converts linear force into rotational force to engage the brake shoes against the drum in drum brakes.
Step-by-step explanation:
The s-cam in s-cam brakes, also known as slack adjuster cam, is an essential component in drum brakes used in heavy vehicles like trucks and buses. It serves the purpose of converting the linear force applied by the brake chamber into a rotational force to engage the brake shoes against the drum. This action creates friction and stops the vehicle.