System PartsQuestion 6 of 60
What is the function of the S-cam in a drum air brake?
a.To store compressed air for emergencies
b.To warn the driver when pressure is low
c.To force the brake shoes against the drum
d.To drain water from the air tanks
Explanation
When you apply the brakes, air pressure moves the slack adjuster and brake chamber pushrod, which turns the S-cam. The S-cam forces the brake shoes apart and presses them against the inside of the brake drum to create stopping friction. This design is called an S-cam brake because of the cam's shape.
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Related questions on this topic
- At about what pressure does the governor typically cut out the compressor from pumping air?
- Why do air storage tanks have a drain valve at the bottom?
- What is the danger of water collecting in the air storage tanks?
- Spring brakes on a truck are held in the released position by what?
- What happens to the spring brakes when air pressure drops to a very low level (for example, 20 to 45 psi)?
- Why do heavy vehicles use a dual air brake system?
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