Final Answer:
The S-cam is what turns and forces the brake shoes away from one another, pressing them against the inside of the brake drum. Option 3 is the answer.
Step-by-step explanation:
In a drum brake system, the S-cam is a crucial component responsible for spreading the brake shoes apart. When the brake pedal is pressed, it activates the master cylinder, which then transfers hydraulic pressure to the wheel cylinders. The wheel cylinders push the brake shoes against the brake drum. The S-cam, connected to the brake camshaft, rotates as a result of this hydraulic pressure. As the S-cam turns, it pushes the brake shoes outward, creating friction against the inner surface of the brake drum and generating the braking force needed to slow down or stop the vehicle.
Understanding the role of the S-cam is essential in comprehending the mechanics of drum brake systems.
Option 3 is the answer.