Friction in an S-cam brake is caused when the brake shoes and linings:
Answers
Press against the outside of the brake drum.
Press against the inside of the brake drum.
Push against each other.
The Correct Answer and Explanation is :
The correct answer is: Press against the inside of the brake drum.
Explanation:
In an S-cam brake system, friction is generated when the brake shoes and linings press against the inside of the brake drum. This type of braking mechanism is commonly used in heavy vehicles like trucks and buses. The system operates using a camshaft (the “S” cam) to actuate the brake shoes.
Here’s how the system works:
- Brake Drum and Shoes: The brake drum is a cylindrical component attached to the wheel. The brake shoes, equipped with friction linings, are positioned just inside the drum.
- Action of the S-Cam: The S-cam is a rotating camshaft that pushes the brake shoes outward when it turns. The cam is shaped like an “S”, with a tapering design. When the brake is engaged, the air brake chamber applies pressure to a pushrod, which turns the S-cam. This rotation forces the brake shoes to expand.
- Friction and Braking: As the brake shoes are pushed outward by the cam, they come into contact with the inside surface of the brake drum. The friction between the brake shoe linings and the drum generates the braking force needed to slow or stop the vehicle. The harder the brake shoes push against the drum, the more friction is generated, which leads to a greater stopping power.
- Frictional Heat: As the brake shoes rub against the drum, heat is generated. In high-performance braking situations, this heat can accumulate, leading to potential brake fade if the system is not properly maintained or if excessive heat is generated.
In summary, friction in the S-cam brake system occurs when the brake shoes with their linings press against the inside of the brake drum. This contact creates the friction necessary to stop the vehicle.