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Car Safety Technology: The History and Evolution of Car Brakes, Seatbelts, and Airbags

Photo by Lee Haywood on Flickr / CC BY-SA 2.0.

Ever since the first gasoline-powered automobiles charted their courses in 1886, safety has been a major concern of the automotive world, for both manufacturers and consumers. From the first brakes to the newest technological marvels of autonomous driving, we will present you the evolution of car safety technology.

The Brakes: From Simple Beginnings to Brake Assist Systems

Image courtesy of Pixabay.com, hosted under CC0.
Image courtesy of Pixabay.com, hosted under CC0.

Originally, the braking system was comprised of a simple wooden block and lever, where the driver engaged the lever, thereby bearing the wooden block down upon the wheel, which, in turn, stopped the vehicle. This system, however, was widely used on carriages, and wasn’t the best solution for the first cars.

Brake Drums and Shoes: Why the Shoe Brake was Moved to the Inside

A render of a drum brake. Image courtesy of wikipedia.org.
A render of a drum brake. Photo by Wapcaplet on Wikimedia Commons / CC BY-SA 3.0

It was the Michelin brothers who first replaced the steel rimmed wheels with a new rubber tire. This rendered the lever and drum system ineffective, and another solution was needed.

This is when the drum, still in use today, was invented. The original idea of wrapping a cable around a drum and securing it to the vehicle’s chassis was the work of Gottlieb Daimler in 1899. The creation of the ‘forefather of the modern brake’, as the drum is often called, is credited to the French manufacturer Louis Renault, who patented the principle in 1902.

However, the system was far from perfect. At the beginning, the drum was an external feature, which caused some problems. As the drum wasn’t shielded from the elements, dust, heat and water caused grip issues, thereby decreasing the efficiency of braking. This is why the shoe brake was moved to the inside of the drum – the internal expanding shoe brake eliminated the issues caused by dust and water.

Hydraulic Power for Efficient Braking

The above mentioned drum braking system was still manual – the levers, rods and cables operated the shoes mechanically. In 1918, hydraulic power hit the scene when Malcolm Loughead introduced his four-wheel hydraulic braking system. This system incorporated fluids that transferred the force of the pressed pedal onto the pistons and ultimately down to the brake shoes. It wasn’t long before this concept gained momentum and was a standard component of the high-end vehicles during the 1920s.

Disc Brakes Prove to be Superior

Image courtesy of wikipedia.org.
Photo by David Monniaux on Wikimedia Commons / CC BY-SA 3.0

The disc brakes were the next major development in the braking system. First patented by William Lanchester in 1902, the disc didn’t become a big deal until the 1950s, when Jaguar equipped three cars with disc brakes for the Le Mans race. All three cars performed extraordinary well, thanks to the superior braking capabilities provided by the disc.The disc became more popular after the race. Today, most cars have disc brakes on the front wheels, and although a large number of cars still have drum brakes on the back, new models often come with disc brakes on all four wheels.

Modern Braking Systems

The development of the braking system didn’t stop with the disc. Today, driver safety and convenience is at the forefront and complementary systems such as ABS, EBD and Brake Assist tune up the safety of modern cars.

  • The Anti-Lock Braking System (ABS) makes sure the driver is able to maintain vehicle control during heavy braking. The system monitors wheel speeds and prevents wheel lockup during heavy braking by rapidly pulsing individual brakes and thereby releasing pressure on individual wheel brake lines.
  • Electronic Brake Force Distribution (EBD) is always coupled with ABS. The system automatically varies the force applied to each brake, depending on a number of conditions, such as current road conditions, loading, speed and more, thereby maximizing braking power without losing vehicle control.
  • Brake Assist Systems are the latest technological marvel – the system identifies emergency braking attempts by measuring the force applied to the brake pedal and how fast the pedal is stepped on. Once an emergency braking attempt is detected, the system applies the extra needed pressure to stop the car in time, as several studies have proved that drivers are often “too soft” when it comes to braking.

Windshields: How Glass became Indestructible

Image courtesy of Bill Abbott on Flickr, licensed under CC BY-SA 2.0.

Back at the beginning of the 20th century, when horseless carriages were the main transportation method, there was a need to defend against the elements and pesky debris like sharp rocks. This is how the idea that a piece of glass would provide adequate protection was born. The main problem with this approach was that the glass would shatter rather easily during an accident and present yet another danger to the driver and the passengers.

Even the Ford Model T, one of the most sold vehicles in the world, offered optional windshields, headlights and speedometer, which raised its price from $850 to $950. As the number of vehicles kept rising, so did the number of incidents, and many drivers quickly realized that the windshield was a great danger in such instances. Some sources state that even Henry Ford was hurt because of shattered glass. Soon after it was determined that regular glass wasn’t the best solution, engineers started working on finding a safer alternative.

The Introduction of Laminated Glass made Windshields Safer

Things changed in 1919, when laminated glass was chosen for new windshields because of its superior properties and lower chance of shattering.

As many great inventions, laminated glass was also discovered by accident.

Edouard Benedictus discovered the shatter resistant properties when he accidentally dropped a flask he believed was empty – but it was actually filled with a small amount of cellulose nitrate that had dried up – and this held the flask together. After some time, he developed a technique where he added a thin cellulose layer between two glass plates, which made the glass shatter resistant.

There was one issue with laminated glass, however – the cellulose layer would darken over time, become brittle and could be punctured easily. The issue was solved in 1938, when Carleton Ellis patented a synthetic resin known as Polyvinyl Butyral (PVB), which made the laminated glass clearer, stronger and UV resistant.

Tempered Glass Proved to be more Resistant than Laminated Glass

That same year, another type of glass was introduced – presented under the name of Herculite, the Pittsburgh Plate Glass Company introduced tempered glass, which proved to be considerably more shatter resistant. Tempered glass is made in an atmospheric oven, where the glass is heated and thereby hardened, then rapidly cooled. Through the process of rapid cooling, the glass forms an even harder outer shell. When it breaks, it shatters into small pieces, as opposed to regular glass, which lowers the chance of serious injury considerably.

The Modern Windshield offers Safety on Several Levels

Image courtesy of David Fulmer on Flickr, licensed under CC BY 2.0.
Image courtesy of David Fulmer on Flickr, licensed under CC BY 2.0.

Today’s laminated glass is several times more robust than the laminated glass from the past century. Modern windshields are larger, provide increased visibility, some even extend to the rooftop. They absorb UV rays and also deflect a significant portion of infrared rays, which means less internal heat.

Today’s cars use laminated windshields and tempered glass for side and back windows.

The future of windshields looks interesting, with several automakers working hard on providing us with a sensor equipped interactive windshield that will provide information about the vehicles surroundings.

Seatbelts: From a Simple Strap to Life-Saving Guards

Image courtesy of Steven Depolo on Flickr, licensed under CC BY 2.0.
Image courtesy of Steven Depolo on Flickr, licensed under CC BY 2.0.

The seatbelt, which is the most common form of car safety known today, wasn’t always a standard feature. From aircrafts to automobiles, the seatbelt has ranged from a lap belt, sash, belt-in-seat, and 3, 4, 5, or 6-point harness. Originally, the lap belt was a two-point system composed of a single strap across the hips/thighs.

Although there were several attempts to introduce seatbelts as a safety feature into cars, the public wasn’t thrilled.

The public felt “uneasy”, “pinned down” and “unsafe” wearing them, and the seatbelt was thought of as a nuisance. It even went so far that they were torn or cut out of cars that tried to offer them as a standard feature.

The Dawn of the 3-Point Seatbelt

However, with traffic incidents on the rise, engineers worked hard to bring innovations that would make cars safer. During the late fifties, the next iteration of the seatbelt was presented: the lap/shoulder belt (3-point), also known as a combination belt. This system used two straps that met at the hip’s side and locked into place. Swedish inventor Nils Bohlin developed this 3-point system in 1959 while working at Volvo. That same year, Volvo introduced the 3-point seatbelt as a standard feature in Sweden and in 1962 in the U.S. The 3-point system is still in use today.

A Long Way to Go: Gaining Public Acceptance

Image courtesy of SmartSign on Flickr, licensed under CC BY 2.0.
Image courtesy of SmartSign on Flickr, licensed under CC BY 2.0.

Even with the development of a 3-point seatbelt going far back, the seatbelts were viewed as an optional feature for quite some time and the public continued to ignore them. Eventually, research proved how many lives had been saved with the implementation of the seatbelt as a safety feature, so the public’s opinion on the seatbelt gradually changed.

The NHTSA mandated the installation of seatbelts in new automobiles along with energy absorbing steering wheels, headrests and shatter-resistant windshields.

How the Seatbelt Became the Law

Image courtesy of West Midlands Police on Flickr, licensed under CC BY-SA 2.0
Image courtesy of West Midlands Police on Flickr, licensed under CC BY-SA 2.0

With help of promotion and efforts of safety organizations, seatbelts also became compulsory, with New York being the first state to pass a law that required that vehicle occupants wear seatbelts in 1984. The legislation differs depending on state, so wearing seatbelts in the back seats is not mandatory in some states. In the EU, however, a 2006 law dictates that all occupants have to wear seatbelts.

Air Bags: From First Concepts to Improved New Types

A cushion housed inside the steering wheel to protect the driver upon impact is precisely how the concept of the air bag started. Composed of three essential parts, the air bag itself is made of a thick nylon material that is folded and placed in the dashboard or steering wheel, and a sensor identifies when to inflate the bag.

The Humble Beginnings

Image courtesy of Andrew Comings on Flickr, licensed under CC BY 2.0.
Image courtesy of Andrew Comings on Flickr, licensed under CC BY 2.0.

Early attempts can be traced back to the early 1940s. John W. Hetrick, who is credited as the inventor of the air bag in the U.S., utilized his knowledge of compressed air from torpedo launches, which he obtained in the United States Navy. He requested his first air bag patent in 1951.

That same year, German engineer Walter Linderer also requested a patent for his version of the air bag. They both got their patents approved just three months from each other in 1953. In 1964, Yasuzaburou Kobori from Japan worked on a safety net idea, but his work was not widely used for years to come. At the beginning, the air bags were not as effective due to a lengthy process of air bag deployment; they just couldn’t be inflated quickly enough.

A Major Breakthrough led to Faster Deployment

Image courtesy of Simon Yeo on Flickr, licensed under CC BY 2.0
Image courtesy of Simon Yeo on Flickr, licensed under CC BY 2.0

A major breakthrough in 1967 finally solved the issue of slow deployment. The new electromechanical crash sensor was able to inflate the air bag in less than 30 milliseconds. Instead of compressed air, sodium azide was used because of its superb expanding abilities.

Ford and General Motors toyed with the inclusion of air bags in their line up, but discontinued them entirely by 1977 because of lack of interest from their buyers. Another issue with air bags was that they were often considered a substitute for seatbelts, and as the seatbelt popularity grew, the public showed no interest in having both in their cars. It wasn’t until 1981 when Mercedes-Benz demonstrated that air bags actually were a standalone safety feature and not a supplement to seatbelts, and offered their high-end S-class with both seatbelts and several air bags in its restraint system.

In 1988, Chrysler was the first to offer air bags as standard equipment and the rest of auto manufacturers jumped on board with the new safety feature.

As more manufacturers offered air bags, more was invested in research and development, resulting in a number of important improvements, some of which include higher deployment thresholds (meaning the air bag won’t detonate at speeds under 12 MPH), use of lighter materials and less propellant, adjustable inflators, improved sensors, and more.

How Does the Car know when to Deploy an Air bag?

Image courtesy of Michael Sheehan on Flickr, licensed under CC BY 2.0.
Knee airbag. Image courtesy of Michael Sheehan on Flickr, licensed under CC BY 2.0.

Air bags are equipped with sensors that signal when it’s time to deploy. The air bag will be deployed when the sensor detects a collision force equal to running into a brick wall at 10-15 MPH. When such a force is detected, a mechanical switch flips and closes an electrical contact, which signals that a crash has occurred.

Today’s air bags have advanced sensory features that take into account the size of the occupant, seat position, seatbelt use and crash severity.

After these factors are considered, a mixture of sodium azide and potassium nitrate are combined to quickly react producing a large pulse sensation of hot nitrogen gas. This process rapidly inflates the air bag – the bag bursts from storage at 200 mph – and within seconds, the air bag begins to deflate through tiny holes in the bag, so the occupant can move.

What Types of Air Bags are There?

Today, there are several types of air bags that protect not only the driver, but other passengers as well.

  • Frontal air bags are located in the steering wheel and the dashboard and protect during frontal collisions. Dual frontal air-bags are mandatory for all cars sold in the U.S.
  • Side-impact air bags (SABs) protect the head and chest upon impact. The main types include torso and curtain air bags, and they deploy when the vehicle is hit in the side.
  • New types of air bags include knee air bags, which deploy under the dashboard and protect the knees of the occupant, thereby preventing kneecap injuries that are very common in frontal collisions. Another innovation comes from Chevrolet, who added a “front center air bag” to several of their models. This air bag deploys between the front seats of the car and protects from the collision coming from the opposite side. Inflatable seatbelts are another new approach: such a seatbelt helps spread the force of the impact over a wider area of the body, thereby lessening seatbelt related injuries.

The Rise of Car Tech: Driver Assistance Technologies that Contribute to Safety

Image courtesy of pixabay.com.
Image courtesy of Pixabay.com, hosted under CC0.

With a myriad of technological advancements, cars were slowly equipped with more and more safety features that assist the driver in a number of ways. Here’s a short list of the more recent driver assistance technologies that contribute to safety:

  • The GPS, introduced during the 1990s, was one of the earliest driver assistance technologies.
  • Cruise control was another feature that assisted the driver by making the ride more comfortable, and today’s adaptive cruise control is responsive to the car’s surroundings and can regulate speed to current traffic flow.
  • Blind Spot Monitoring Systems removes the issue of the blind spots by using a plethora of sensors to alert the driver to potential hazards through an alarm or image transmitted onto the screen/mirror. This first ever system appeared on the 2007 Volvo S80.
  • Electronic Stability Control dates back to the 1995’s Mercedes-Benz S 600 Coupe. This anti-skid concept only intervenes when the driver’s intended steering location and the actual vehicle location are not the same.
  • Lane Departure Warning Systems help the vehicle stay in the lane. The first system was introduced in 1992, but the first commercially available system came to the U.S. in 2004.
  • Automatic Emergency Brake has the power to potentially eliminate or reduce the impact of an expected collision. AEB systems alarm the driver about an upcoming crash and engage maximum braking force.

What Does the Future Hold?

Looking ahead, vehicle-to-vehicle (V2V) communication abilities will be an option where cars can warn each other about road conditions and traffic patterns. Self-driving cars have already been tested over 200,000 miles in California and Nevada. They can identify delays in traffic and re-route faster than humans and can also recognize a pedestrian crossing the road thanks to sensors.

Pedestrian safety is advancing with radars and cameras being developed to decrease the speed of impact in case of an incident. Already in place with some luxury makers, Honda and Ford are diligently working toward this concept.

Alerting the driver to speed variations could improve safety for everyone on the road and that is exactly what Intelligent Speed Assist does. ISA incorporates what the driver’s speed should be, what it is, roadway conditions, geographical areas, hazardous areas and advises or adjusts the speed of the vehicle automatically.


With driver-focused technology taking center stage, safety is ever-changing in today’s cars. From cars that assist the driver to ones that do the driving for them, cars of the future are closer than they appear. One thing is certain; manufacturers across the globe are focused on the combination of what matters most: safety and convenience.

What safety features do you find most useful?

Which safety features does your car have?

Are you looking forward to new safety tech that is being developed?

Let us know what you think in the comments below!