Arizona Air Brakes CDL Practice Test

Which brake type is most commonly used in commercial vehicles?

1. Wedge brakes

2. Disc brakes

3. S-Cam brakes

4. Drum brakes

The correct answer is: S-Cam brakes

The most commonly used brake type in commercial vehicles is the S-Cam brake system. This design is specifically tailored for heavy-duty vehicles and is favored for its effective performance under the demanding conditions faced by trucks and buses. The S-Cam brake functions by using a cam that, when rotated, pushes out the brake shoes against the drum, allowing for strong and reliable braking power. S-Cam brakes are popular because they provide a good balance of cost-effectiveness, durability, and maintenance requirements, making them particularly suitable for the high-stress environments that commercial vehicles operate in. Their ability to deliver consistent braking force and ease of servicing contribute to their prevalence in the trucking industry. Other brake types, such as wedge brakes, disc brakes, and drum brakes, while they have their own applications and advantages, do not match the widespread use and advantages of S-Cam brakes in the context of commercial vehicles. Wedge brakes tend to be less common in heavy applications because they require more precise adjustments. Disc brakes, though increasingly popular in some newer models for their performance, have not yet surpassed S-Cam brakes in overall usage. Drum brakes, while traditional and still used, have limitations in heat dissipation compared to S-Cam systems, especially under heavy load