How does a car opperate with the emergency break on?

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The e break stops the wheels from turning so it doesn’t roll downhill. So how are you able to drive with it on.

In: Engineering

The e-brake or parking brake is just a cable connected to the (usually) rear brakes on your car. Most cars have a powerful enough motor to overcome the friction from one set of brakes being on.

The torque of the drive train are able to overcome the braking force of the brakes. Not ever car can do it, most can.

The wheels are stopped by the friction provided by the emergency (parking) brake. It’s strong enough to keep the wheels from turning on their own, but not always enough to keep the power from the motor from turning the wheels.

Think of putting a piece of paper against a wall. Without pushing on the paper, The paper will fall on its own just like a car will roll down a hill if the parking brake isn’t set (assuming a manual transmission in neutral). When you press the paper against the wall, it will stay there because of the friction between the wall, the paper, and your hand. That the car on the hill with the brake set. Now imagine holding the paper against the wall with one finger, but pulling it down hard with your other hand. That’s driving with the brake on. It will be a bit more difficult to pull the paper out, but entirely possible.

The parking brake is designed to hold the weight of the car on an incline. The engine is powerful enough to propel that same weight up the same hill and even gain speed while doing it. So the engine has enough power to overpower the holding force of the brakes and move the car. I should also point out that the parking brake is only engaging the rear brakes through mechanical force in most vehicles. When you step on the brake pedal you are applying all 4 brakes with hydraulic force that is also amplified by a booster.

You should not be able to drive with it on, but often the amount of braking force it provides is not enough to overcome the torque from the engine. If you drive with the e-brake on, you will either lock up your rear wheels and shred the tires or you will overheat the brakes and severely damage them.