You're 16 years old.
Your father has decided it would be a great idea to take you to the steepest
hill in town and make you stop precariously at the stop sign that is halfway up
the hill. You're driving a stick shift. As you stop, he reaches over and puts on
the emergency brake. You notice three cars pulling up behind you. Your father
snickers. You break into a cold sweat. But for a second, you feel safe. Because
the emergency brake is on. But what exactly is holding you in place?
Emergency brakes are a secondary braking
system installed in motor vehicles. Also known as e-brakes, hand brakes and
parking brakes, emergency brakes are not powered by hydraulics and are
independent of the service brakes used to slow and stop vehicles. There are
state and federal laws requiring emergency brakes for motor vehicles
There are four types
of emergency brakes:
·
Stick lever, which is
generally found under the instrument panel (found in older-model vehicles)
·
Center lever, which is
found in between separated front seats
·
Pedal, which is found
to the left of the floor pedals
·
Electric or push
button, which are found among st the other console controls
Because most modern braking systems have
fail safe measures and warning systems, such as on-dash brake-warning lights and
low-fluid sensors, the emergency brake is most often used as a parking brake
device. But the e-brake is called an emergency brake for a reason -- using it
can save your life.
Read on to discover how emergency brakes keep
you from rolling down that hill.
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This one little lever can mean the difference between a car staying put or rolling into the house down the hill.
Using only levers and cables, each type of
emergency brake is completely mechanical and bypasses the normal brake system.
This ensures that a vehicle can be brought to a complete stop if there's a
failure of the brake system
When you set the emergency brake, the brake cable
passes through an intermediate lever, which increases the force of your pull,
and then passes through an equalizer. At the U-shaped equalizer, the cable is
split in two. The equalizer divides the force and sends it evenly across the
two cables connected to the rear wheels
Motor vehicles use either drum brakes or disc
brakes. Drum brakes are common in the rear wheels, while disc brakes are most
common on the front wheels (or all four wheels). In a rear drum situation, the
emergency brake cable runs directly to the brake shoes, bypassing the hydraulic
brake system. In this simple, mechanical bypass, the emergency brake system
requires no extra parts to control the brakes
Cars with rear disc brakes have a more
complicated emergency brake system, sometimes requiring an entire drum brake
system to be mounted inside of the rear rotor, called an exclusive parking
brake or auxiliary drum brake
When the vehicle has rear disc brakes without
an auxiliary drum brake, a caliper-actuated parking brake system is used. With this
system, an additional lever and corkscrew is added to the existing caliper
piston. When the emergency brake is pulled, the lever forces the corkscrew
against caliper piston, and applies the brakes, again bypassing the hydraulic
braking system.
Electric e-brakes are available on some cars
today. Instead of having a pedal, stick or center console lever, a small button
on the dash signals an electric motor to pull the brake cable. Advanced
electric brake systems utilize computer-controlled motors to engage the brake
caliper
When to Use the Emergency Brake
Using the emergency brake to stop a moving
vehicle outside of a total brake failure is not recommended and can damage your brake system. This is why
it's not a good idea to pretend you're a race car driver and slam on the e-brake
to spin in a circle. Driving with your emergency brake engaged can also cause
damage to the emergency brake cable and the service brakes. If this happens to
you, have your brake shoes and rotors checked as soon as possible, to ensure everything is OK.
The most common use of the emergency brake is
as a parking brake. Those who drive manual transmission vehicles, or stick
shifts, usually engage the emergency brake every time they exit the car. If not
engaged, the car might just roll away all on its own. Automatic transmission
drivers tend to use the emergency brake far less, if at all.
It's recommended that you engage the emergency
brake anytime the vehicle is parked on a hill, whether it's an automatic or
standard transmission. For an automatic, setting the emergency brake before you
release the service brake pedal will keep weight off the transmission, making
it easier to shift out of park .
The emergency brake can also be used as an aid
to manual transmission drivers to prevent rollback when starting on a hill.
Pulling the emergency brake while stopped, and then letting it out as you
release the clutch can be tricky, so you might want to practice this maneuver before
depending on it. Make sure there's no one behind you if you've never done it
before -- especially if your father is with you, and you only have a learner's
permit.
It's easy to forget that the emergency brake
is on if you don't use it often. To prevent driving off with the brake still
engaged, try to set the brake as hard as you possibly can. Then leave an item
on or around the lever, such as a cell-phone charger cord or a spare piece of
paper.
Emergency brakes can be dangerous if they're
not properly used. Read on to learn how to use emergency brakes the right way.
Dangers of the Emergency Brake
Even though the emergency brake cable is
housed in a protective sleeve, with infrequent use, the cable can become
corroded and rusted. This can result in cable failure just when you need it the
most. Normal use prevents buildup and keeps the cable in good condition, though
you should have the emergency brakes routinely inspected, as they sometimes
need to be tightened.
In cold temperatures, the emergency brake
cable can become frozen and fail to release when the lever is disengaged.
Parking in a garage or other protected area can help you to avoid this problem.
But if you have to park outside and it freezes up, you should
not attempt to drive your vehicle. Solutions include waiting it out or jacking up the car and
using a hairdryer. The best option in freezing weather is to simply not use the
emergency brake at all. If you're on level ground in a manual vehicle, put the
car in first or reverse and skip the e-brake.
Be aware that in some vehicles, the emergency
brake engages the front brakes, not the rear brakes. Knowing which brakes are
set and properly chocking your vehicle wheels will protect you in situations
where you must jack up the vehicle. Refer to your service manual before you
raise the car. Believing the rear brakes are engaged when they aren't can be
extremely dangerous.
Now onto the big question: Is using the
emergency brake safe when the other brakes fail? Yes and no. Pulling the brake
lever quickly will cause the vehicle to fishtail, lock up or skid, essentially
removing control of the vehicle from the driver. But if you're ever in the
highly unlikely but extremely serious situation of having your service brakes
fail to function, try to stay calm and pull the emergency brake lever up slow
and steady, bringing the vehicle to a longer but more controlled stop.
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