- Cruise control (sometimes known as speed control or
autocruise, or tempomat in some countries) is a automatically
controls the speed of a motor vehicle. The system is a
servomechanism that takes over the throttle of the car to maintain a
steady speed as set by the driver.
The purpose of a cruise control
system is to accurately maintain a speed set by the driver without any outside
intervention by controlling the throttle-accelerator pedal linkage.
- Adaptive Cruise Control
Not only maintains your set speed, but your following
distance as well; provides some limited braking.
- WHAT IT DOES: Automatically speeds up and slows down your
car to keep a set following distance relative to the car ahead. Provides some
braking.
- WHAT IT DOES NOT DO: You need to understand how much braking the
system can do—some will brake to a stop, most will only brake so much.
The earliest variants of cruise control
were actually in use even before the creation of automobiles. The inventor and
mechanical engineer James Watt developed a version as early as the 17th
century, which allowed steam engines to maintain a constant speed up and down
inclines. Cruise control as we know it today was invented in the late 1940s,
when the idea of using an electrically-controlled device that could
manipulate road speeds and adjust the throttle accordingly was conceived.
Working:
The cruise control system
controls the speed of your car the same way you do – by adjusting the throttle
(accelerator) position. However, cruise control engages the throttle valve by a
cable connected to an actuator, rather than by pressing a pedal. The
throttle valve controls the power and speed of the engine by limiting how
much air it takes in (since it’s an internal combustion engine). These are commonly located on the steering
wheel or on the windshield wiper or turn signal stalk. The SET/ACCEL knob sets
the speed of the car. One tap will accelerate it by 1 mph, two by 2 mph and so
on. Tapping the knob in the opposite direction will decelerate the
vehicle. As a safety feature, the cruise control system will disengage as
soon as you hit the brake pedal.
The cruise
control system actually has a lot of functions other than controlling the speed
of your car. For instance, the cruise control pictured below can accelerate or
decelerate the car by 1 mph with the tap of a button. Hit the button five times
to go 5 mph faster. There are also several important safety features -- the
cruise control will disengage as soon as you hit the brake pedal, and it
won't engage at speeds less than 25 mph (40 kph).
The system
pictured below has five buttons: On, Off, Set/Accel, Resume and Coast. It
also has a sixth control -- the brake pedal, and if your car has a Manual Transmission the clutch pedal is also
hooked up to the cruise control.
·
The on and off buttons don't actually do
much. Hitting the on button does not do anything except tell the car that you
might be hitting another button soon. The off button turns the cruise control
off even if it is engaged. Some cruise controls don't have these buttons;
instead, they turn off when the driver hits the brakes, and turn on when the
driver hits the set button.
·
The set/accel button tells the car to maintain the
speed you are currently driving. If you hit the set button at 45 mph, the car
will maintain your speed at 45 mph. Holding down the set/accel button will make
the car accelerate; and on this car, tapping it once will make the car go 1 mph
faster.
·
If you recently disengaged the cruise control by hitting the
brake pedal, hitting the resumebutton will command the car to accelerate
back to the most recent speed setting.
·
Holding down the coast button will cause the car
to decelerate, just as if you took your foot completely off the gas. On this
car, tapping the coast button once will cause the car to slow down by 1 mph.
·
The brake pedal and clutch pedal each
have a switch that disengages the cruise control as soon as the pedal is
pressed, so you can shut off the cruise control with a light tap on the brake
or clutch.
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