Why can a vehicle still accelerate when the emergency brake is engaged?
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The emergency or parking brake usually just applies enough force to some of the wheels (usually the rear wheels) just to hold the car in place on a moderate slope – so nowhere near as much as when the car is on and your regular brake pressure (via the hydraulic brake cylinder) is acting on it. Since your average car engine is powerful enough to accelerate your car up said slope, it is more powerful than the mediocre braking force that the e/parking brake applies.
Now, whether your engine can outmatch your regular brakes, comes down to how much hps and torques your engine has vs. how good your brakes are.
If your parking brake isn’t cutting it – say you live in San Francisco – you can get that cable tensioned a bit tighter I’m sure.
Cars don’t have “Emergency brakes”, that would be the foot pedal. The hand lever is called a parking brake and that is all it is intended for. It clamps down on the rear brakes when you’re parked so all the weight isn’t on the gears of the transmission.
Source: Two years of Automotive Technology classes.
car haven’t had emergy brakes for many decades, they have two independent brake circuits and a parking brake
Many cars don’t have emergency brakes. Most very modern cars do, and the government is expected to make emergency brakes law soon.
The emergency brakes, are not actually a separate system – it’s the same brake system as the regular brake – however, when a radar, camera or laser sensor on the front of the car detects that you are about to hit something, the ABS computer will activate full braking.
There is a related system which is not completely automatic. The car monitors how quickly and hard you press the brake pedal. Because most people don’t press the brake hard enough in an emergency, a computer monitors this, and if you press the brake unusually hard and fast, but not full, the computer will override you and give full emergency braking.
In both of these cases, the emergency braking computer will also send an emergency signal to the engine computer telling it to deactivate the accelerator pedal so that the car can’t accelerate.
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