Why does the brake pedal suddenly become very hard?
2 Answers
The brake pedal suddenly becoming very hard is due to a failure in the hydraulic power assist system. At this time, the brakes are still effective, but require more force to press. Braking, also known as deceleration, refers to the action of stopping or reducing the speed of moving locomotives, vehicles, other transportation tools, or machinery. The general principle of braking involves fixing a wheel or disc on the machine's high-speed shaft and installing corresponding brake shoes or discs on the machine base, which generate braking torque under external force. The car's brake pedal is located below the steering wheel. Pressing the brake pedal causes the brake linkage to be compressed and transmitted to the brake shoes on the brake drum, clamping the brake disc to slow down or stop the car.
I know exactly how it feels when the brake pedal suddenly becomes heavy. As a veteran driver with over 20 years of experience, the most common issue is a faulty vacuum booster. That device is supposed to help reduce braking effort, but once the vacuum hose leaks or the booster diaphragm ruptures, the brakes become extremely stiff, requiring you to stomp on the pedal with all your might. This could be caused by insufficient vacuum at engine idle or aging/cracked tubing. I remember when my car's booster failed—stepping on the pedal felt like pushing against an iron plate—it was truly dangerous. Never continue driving under these circumstances. Pull over immediately, turn on hazard lights, and first check if the engine is running normally while listening for any hissing air leaks. However, it's best not to attempt repairs yourself—call a tow truck and take it straight to the repair shop. Brakes are a safety-critical system. Regular inspections of the vacuum system and brake lines can prevent major issues—don't take this lightly.
