By Steph

Lauren & Jenny

Seat Belts

Seat belts improve the safety of the passenger.The seat belt was introduced in 1949 by Nash Motors, but it was not until the mid-1950s that most carmakers began offering seat belts as optional safety features. They crossed over a passenger's lap, securing him or her to the seat in order to prevent a collision with the dashboard, steering wheel, or windshield in an accident. Unfortunately the seatbelt was far from perfect, and nasty head, spinal, and other injuries continued to occur.

Crumple Zones

Bela Berenyi, an engineer at Mercedes, came up with a safety concept that would completely change how cars were designed and built. Before 1959, people believed the stronger the structure, the safer the car. But in actuality, such construction proved deadly to passengers, because the force from impact went straight inside the vehicle and onto the passenger. Berenyi found a way to dissipate the force of a crash before it reached the passenger. In the end, he designed two "crumple zones" -- one in the front of a car and one in the back. Crumple zones relied on a skeletal frame of special materials that would crumple in predictable ways, absorbing the energy of a collision.

Air BagsThe Air Bag was Invented in 1952 and began to be fitted in cars in 1970 when it was found out that fewer than 15% of all Americans wore seatbelts. Eight years later, all U.S. car manufacturers were required to follow suit.

By the late 1990s, a rising number of airbag-induced deaths had created a new concern: the airbag itself could be dangerous. The explosive force of a filling airbag was powerful enough to injure and possibly kill both adults and children. In almost every case, airbag injuries involved women under 5'4" or adults and children who were either unbelted or improperly restrained.

As a solution a computer now decides how airbags should deploy. It uses an electronic scale that directs the bag to deploy only if the rider is above a certain weight, and it can deploy at two different speeds using one of two initiators. In a minor accident, only one initiator fires, and the bag inflates more softly and to a smaller size; in a high speed accident, both initiators fire.

Wind Shields

The use of plate glass in early windshields created the danger of the "glass necklace," a situation in which passengers could fly headlong into and through the windshield during a head-on collision.

Early this century, two European scientists independently invented a solution to deadly windshields. While working in his lab, French scientist Edouard Benedictus accidentally knocked a flask to the floor. To his amazement, the glass did not break. Looking closer, he discovered that the chemical that had been inside the flask, nitrocellulose, had dried up, leaving an adhesive film that kept the numerous bits of fragmented glass from separating. Benedictus went on to develop a window consisting of two layers of plate glass held together by layer of cellulose.

In the 1950s, cars came off the line with side and rear windows of tempered glass. Tempered glass is made by placing one piece of glass into an atmospheric oven, which heats and hardens the glass. This treated glass can withstand forces of hundreds of pounds per square inch. When broken, it breaks into smooth beads that do not cut the skin, and unlike safety glass, rescuers can cut into it to reach victims trapped in a car

Brakes

The first cars had brakes only on the back wheels, which led to much skidding and swerving. Brakes on all four wheels did not appear in the United States until 1920, when they were introduced in high-priced cars.It wasn't until the advent of the new Ford Model A in 1927 that four-wheel brakes became standard fare in most cars.

To combat this, automakers devised anti-lock brakes. Relying on a computer to monitor the speed of each wheel, the car can tell when a wheel is beginning to slide and can apply an automatic series of braking pulses, which are faster than those created by a human driver. Anti-lock brakes can stop a car faster in such a situation than a human driver can and also allow the driver to maintain steering control.