Car brakes do work when the engine is off. The brakes in a car are part of a separate system called the braking system, which is independent of the engine and operates on hydraulic pressure. This means that even when the engine is off, the brakes can still be applied and will function as intended.
When you press the brake pedal, a series of actions are set in motion to stop the car. The force you apply to the brake pedal is transferred to the master cylinder, which is connected to the brake fluid reservoir. When the brake pedal is pressed, the master cylinder pressurizes the brake fluid, which then flows through the brake lines to the brake calipers or wheel cylinders.
In a disc brake system, the brake fluid applies pressure to the brake calipers, which squeeze the brake pads against the brake rotor, creating friction and stopping the rotation of the wheels. In a drum brake system, the brake fluid applies pressure to the wheel cylinders, which push the brake shoes against the brake drum, creating friction and stopping the rotation of the wheels.
The hydraulic pressure created by the brake fluid remains constant, regardless of whether the engine is on or off. This means that the brakes will remain functional even when the engine is off. However, it is important to note that some newer cars have an electric brake booster, which relies on the power from the engine to provide additional braking assistance. In these cars, the braking system may still function with the engine off, but the braking force may be reduced.
In addition to the hydraulic braking system, cars also have a mechanical parking brake, also known as the handbrake or emergency brake. This brake is completely separate from the hydraulic system and is manually operated. It is designed to keep the car stationary when parked or in an emergency situation.
The parking brake is typically engaged by pulling a lever or pressing a button, and it locks the rear wheels in place to prevent the car from moving. Unlike the hydraulic brakes, the parking brake does not rely on any power from the engine and can be operated with the engine off. However, it is important to note that the parking brake is not designed to provide the same stopping power as the hydraulic brakes and should not be relied upon as the primary means of stopping the car.
In conclusion, car brakes do work when the engine is off. The brakes in a car operate on hydraulic pressure, which is generated by the brake fluid and remains constant regardless of whether the engine is on or off. This allows the brakes to function as intended and provide stopping power even when the engine is off. However, it is important to note that some newer cars may have an electric brake booster, which may reduce the braking force when the engine is off. Additionally, cars also have a separate mechanical parking brake, which can be operated with the engine off and is designed to keep the car stationary when parked or in an emergency situation.