Power Brakes vs. ABS in Cars

Power brakes and antilock brakes are not a new form of braking technology -- both braking systems simply enhance drum- or disc-operated brakes. Because vehicle owners prefer better braking and safety features, car manufactures often pair ABS and power brakes as standard or optional equipment to supplement regular braking capabilities.

Power Brakes

Bendix patented a power-brake system in the 1950s. As the name implies, power brakes assist the vehicle's braking system by providing added braking power. Most power brake systems use a vacuum-boost design; however, Hydro-Boost and electrohydraulic systems are also available. Power brakes essentially use a vacuum and air pressure to provide added braking power. The size of the power-brake diaphragm and amount of intake vacuum decides the intensity of the power-brake assist, for instance, 20 inches of engine vacuum with an 8-inch booster provides about 240 lbs. of brake assist.

ABS

Compared to power brakes, antilock brakes are a more contemporary technology. In 1978, Mercedes-Benz became the first automotive company to make ABS available on its vehicles in the United States. Antilock brakes provide an extra layer of control to standard braking systems. ABS essentially uses sensors and an onboard computer to control and avoid problems with braking. It does this by pumping the brakes faster than humanly possible.

Benefits of Power Brakes

When Bendix introduced power brakes in the 1950s, it enhanced the efficiency of braking systems. Prior to power brakes, bringing a vehicle to a stop could require a large amount of human power. An illustration shows that power brakes can be operated by anyone -- even a 98-lb. little old lady, who, with a light caress of her foot on the brakes, brings two tons of Lincoln Town Car to a quick halt. However, if power-braking systems fail, braking can become difficult. At high speeds, power brakes can lockup, possibly causing a driver to lose control.

Benefits of ABS

When a driver travels at high speeds and slams on the brakes, he runs the risk of causing the brakes to lockup. Applying ABS decreases the likelihood of a vehicle's brakes locking up and skidding, causing the driver to lose control of the automobile. ABS does not engage in normal braking conditions below highway speeds. More advanced ABS applies braking pressure selectively -- decreasing braking pressure on a certain wheel to prevent lockup and promote proper rotation.