All passenger vehicles sold today in the US have anti-lock braking systems. The technology is mandated by the federal government and has been for several decades. In this article, we will look at the history of anti-lock braking systems and see how this life-saving safety technology has evolved over the years.
How they work
Anti-lock braking systems (ABS) work with a car’s braking system to prevent tires from skidding. This allows drivers to maintain steering control when skids occur. The way they work is that each wheel is monitored by a speed sensor and a computer looks for a wheel that stops turning when the car is in motion. This indicates a wheel that has lost traction and is skidding. When the computer senses a skid, it activates a series of hydraulic valves to limit or reduce the braking on that wheel, or on multiple wheels.
The first anti-lock brakes
The Maxaret System was the first anti-lock braking system to be widely used. It was developed by Dunlop Corporation in the late 1940s for use by the aviation industry. The results were spectacular, studies showed that aircraft with the Maxaret System stopped in 70% of the distance of standard braking systems. This was a critical advantage for the aviation industry because it allowed more airstrips to be used and generally improved the safety of all aircraft using it.
Adapted for cars
It wasn’t long before the automotive industry started to get interested in anti-lock technology. The first car company to adapt anti-lock braking to their cars was Jensen Motors. This British firm installed a modified version of the Maxaret System on their top-of-the-line grand touring coupe in 1966. Called the Intercepter, Jensen built just 320 of the luxury coupes. None were exported to the United States
Adoption in the US
The Maxaret System was 100% mechanical, bulky and limited in control. It would take over a decade before the control systems for an anti-lock brake system could be implemented electronically. Kelsey-Hayes was the first company to offer systems to Detroit and in 1969 Ford offered them in its Thunderbird and Continental Mark III models. This system, called the Sure-Track anti-skid system, was for the rear wheels only.
The “holy grail”
The holy grail of automotive anti-skid technology was to also prevent the front wheels from locking up in addition to the rear. This was to maintain steering control during a full-brake panic stop. The first car to offer that ability came from Chrysler Corporation. In 1971, a full, four-wheel anti-lock brake system designed by Bendix Corporation was installed on their Imperial luxury car. The Sure-Brake option cost $351.50 (the 1971 Imperial was around $6,000).
The Sure-Brake system
The Sure-Brake system had a speed sensor on each wheel, and, in the trunk, an electronic control box. The system controlled the two front wheels independently and the two rear wheels together. The Modulators were vacuum canisters that operated cutoff and relief valves to stop hydraulic pressure from going to the wheels.
According to Thompson Hyundai of Baltimore, MD, a certified Hyundai dealer, in 1977, the federal government mandated that all vehicles sold in the US had to have anti-lock brake technology installed. As a result of this brilliant safety technology, untold numbers of lives have been saved and accidents avoided.