Ralph Teetor (1890-1982), a prolific—and blind- inventor, was inspired to invent cruise control one day while taking a ride in a car driven by his lawyer. The lawyer had the habit of slowing down while talking and speeding up while listening. The car's jerky, rocking motion so annoyed Teetor that he became determined to invent a speed-control device.
Teetor received his first patent on a cruise-control device in 1945 after a decade of tinkering, and it was first offered commercially on Chrysler's Imperial, New Yorker, and Windsor models in 1958. Early names for his invention included Controlmatic, Touchomatic, Pressomatic, and Speedostat, before people settled on the familiar Cruise Control.
With cruise control, the driver sets the speed and the system then takes over the vehicle's throttle to maintain that speed. The cruise control gets its speed signal from a rotating driveshaft, the speedometer cable, a speed sensor on the wheels, or from the engine's revolutions per minute (rpm). The car maintains its speed by pulling the throttle cable with a solenoid or a vacuum-driven servomechanism.
Buttons, usually located on the steering wheel, allow the driver to set the speed, accelerate, and decelerate, and return to the set speed after braking. A tap from the driver on the clutch or brake will turn off the cruise control, while pressing the accelerator will allow the car to speed up; releasing the accelerator returns the car to the set speed. Most cruise control systems will not engage at speeds lower than 15 miles per hour (25 kph).
More advanced adaptive cruise-control systems are currently being developed that will automatically adjust a car's speed at a safe following distance, using radar installed behind the front grill.
