How To Operate Your Vehicle’s Cruise Control
In virtually every car that rolls off the factory line, cruise control is a standard, albeit mostly ignored accessory. This feature allows drivers to set a speed and then remove their foot from the gas pedal. A lot of motorists consider it a necessity for long road trips. But, it’s important to note that the feature is only effective on long stretches of open road.
This article will explain how cruise control works. I’ll describe how you can activate it, modify the settings, and disable it, if necessary.
Setting The System
In most vehicles, the cruise control is designated by a series of buttons: “On/Off,” “Set,” and “Resume.” The specific layout will vary slightly depending upon the make and model you’re driving, but it follows this pattern. When you press the “On” button, the system is activated and your car awaits further instruction from you.
Once the “On” button has been depressed, press the “Set” button. The “Set” button instructs your car to maintain the current speed at which you’re traveling. In some makes and models, pressing this button may increase the speed in predefined increments.
At any point when you’re driving with the cruise control activated, it is disabled the moment you press on your brake pedal. If you want to resume the previous speed, simply press the “Resume” button. To slow down without using the brake, some cars have a “Coast” button that reduces the speed by a preset increment. Along with pressing the brake pedal, cars have an off switch that simply disengages the system.
Looking Beneath The Surface
Cruise control manipulates your vehicle’s speed in the same manner as you would while driving “manually”: by changing the throttle position. However, it uses a mechanical actuator that moves the throttle valve, whereas you would engage the accelerator pedal. Because the speed of your car depends on the amount of air in the fuel mixture, an open throttle allows more air and produces more power; a partially open throttle allows less air for a reduced output.
Because the throttle is connected to two cables, one leading to the actuator and the other to the pedal, moving the throttle in any way will manipulate both lines. This is the reason why you’ll notice your gas pedal is moving up and down when the cruise control is engaged.
Depending on your vehicle’s make and model, the actuator could be powered by engine vacuum. Engine vacuum is the difference between intake manifold pressure and atmospheric pressure. In the case of the actuator, this pressure difference is enough to power the device and is controlled by a valve in the assembly which adjusts diaphragm pressure.
There is one limitation which this feature. Up until a few years ago, motorists had to be aware of other automobiles in front of them that were moving more slowly. Otherwise, a collision was imminent. Today, vehicles are being equipped with sensors that can identify slower cars and compensate in order to avoid contact.
