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How Does it Work /
Cruise Control
How Cruise Control Works
Basic Operation and Description
The cruise control system is used to control and maintain a consistent speed of
the vehicle with the help of an electrical or vacuum actuator connected to the engine
throttle. The cruise control system is also known by alternative names such as auto-cruise
and speed control.
A mechanical engineer by the name of Ralph Teetor in 1945, invented the Speedostat,
the modern cruise control system. The idea was the ground speed was calculated by
counting the driveshaft rotations. The throttle position was changed by the actuator
using a controller sensing the rotations. The cruise control system is by default
turned off, but can be activated by the user. Other than the on switch, there are
switches for set, accelerate, resume, cancel and coast features.
Cruise Control Lever (appearance will vary)
While in cruise mode you can use the cancel button or simply tap the brake or
clutch peddle to disable cruise. The memory feature helps to resume the set speed
after disabling the system. The set speed can be decreased with the help of the
coast feature without using the brakes. The throttle can be used to increase the
speed while the car is set is cruise mode. But after it is released, the speed decreases
until it returns to the previously set speed.
Most cruise control systems consist of a control unit, shaft or wheel speed sensor,
control switches, brake switch, throttle body, wiring harness and vacuum lines.
Some systems unitize an electronic throttle body control which responds like a mechanical
link between the throttle and the accelerator pedal which is easily controlled within
the engine management system.
Some latest automobiles have a laser or radar control system which is known as the
autonomous cruise control or active cruise control. With the help of this program
the set distance between the car in front of you is maintained. When the distance
setting is compromised the speed is automatically decreased and then holds an alternative
set speed when the distance increases. Some systems also include the forward
collision warning. In this system, the speed of both the cars is calculated and when the distance
between them is compromised a warning signal is illuminated.
Check Manufacturer Specific Cruise
Control Questions and Answers
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