Which Wheels Does the Foot Brake of a Sedan Control?
2 Answers
The foot brake of a sedan controls all four wheels, while the handbrake only controls the rear two wheels. Working principle of the foot brake: When the brake pedal is pressed, the force applied by the foot causes the piston in the master cylinder to push the brake fluid forward, creating pressure in the hydraulic lines. This pressure is transmitted through the brake fluid to the piston of the brake caliper at each wheel. The caliper piston then pushes the brake pads outward, causing them to rub against the inner surface of the brake drum. This friction generates sufficient force to reduce the rotational speed of the wheels, achieving the braking effect. Braking techniques: When braking, release the brake before the vehicle comes to a complete stop. Continuously pressing the brake can cause a significant impact force at the moment of stopping. The technique is to release the brake once before the vehicle fully stops and then gently press the brake again until the vehicle comes to a halt.
Last time during heavy rain, I specifically observed the braking situation. When the foot brake was pressed, all four wheels braked simultaneously. During regular car washes, I noticed that the brake caliper structures on the inner side of the rims look almost identical, with the front two wheels having larger brake discs. I remember the mechanic mentioning that this is because the front of the vehicle is heavier, requiring about 70% of the braking force to be allocated to the front wheels during braking. Once, a tire shop worker demonstrated the ABS in action, and the brake sensor lines on all four wheels were flashing. However, the foot brake force isn't separately controllable like the handbrake; the entire hydraulic system is interconnected, with four brake lines running from the master cylinder to the wheel cylinders at each wheel. If you slam the brakes in the rain, you can distinctly feel the jerk of all four wheels locking up simultaneously.
