Modern vehicles are perhaps one of the most complicated machines that we deal with in our daily lives. They are an assembly of thousands of parts that work together to ensure that we commute safely and comfortably from one point to another.
There were 182,560 casualties reported in the UK due to road accidents, between September 2015 and September 2016. The number of car occupant KSI (killed or seriously injured) casualties were a staggering 9,480 and it rose by almost 10 per cent compared to previous years.
According to a report, technical faults with the vehicle accounted for nearly 22 percent of these casualties; this is a significant number. It has surged tremendously from the 2005 figures where only 1.5% of accidents happened due to technical faults.
Most of these technical faults include problems related to braking system, lights and tyres. Brake failure was cited as the most common technical fault that caused the maximum number of such accidents.
Function of brakes
Most believe that it is the brakes that stop a car. But in reality, brakes provide the friction that brings the wheels to a halt.
Vehicles that are being manufactured nowadays mostly make use of disc brakes. Disc brakes consist of following components:
- Brake discs
- Brake pads
- Brake master cylinder
- Brake lines
The disc brake consists of a plate like disc which is attached to the wheel. Brake pads are placed within callipers and they are used to squeeze the plate to bring them to a stop. It is exactly similar to how you would stop a spinning plate by squeezing it between your thumb and fingers.
Brake pads usually consist of two layers. The first layer is a high friction material while the second layer is the metal plate that holds the friction material. The friction material comes in contact with the brake disc when the brakes are applied and it stops the brake disc from rotating. The backing plate not only serves as a platform for the friction material but also prevents excessive heat from building up and protects the brake calliper from this heat build-up.
The brake callipers consists of small pistons that push the brake pads against the disc. It is due to this action that the moving wheels are brought to a halt. This motion of pistons is a result of hydraulic action of brake fluid which comes from brake master cylinder.
In order to distribute pressure evenly against the brake disc the calliper is fitted with two or more pistons. Higher number of pistons ensure that brake disc is not damaged due to uneven pressure being applied on its surface. For this reason, in high performance cars there are multiple pistons fitted to the brake callipers.
When we press our foot on the brake pedal there is a hydraulic brake pressure which is built up in the master cylinder. This pressure is transferred from the master cylinder to callipers through the brake lines. In a bid to reduce the efforts taken to apply brakes, modern brake systems have been developed with power assistance that increases the action of our foot on the brake pedal.
Effect of Heat
Heat is the biggest enemy of good braking. An enormous amount of heat is produced when the brake pads press against the brake disc. There is a sophisticated system that has been put in place to remove heat from braking systems, especially the front brakes that are heavily loaded. This system contains internal vanes that carry cool air to the outer edges from the centre of the disc. Due to this ventilation, the brakes become less prone to ‘fading’ and remain cooler.
Fading usually occurs when brakes are overheated and overused. Braking ability decreases significantly when the brake fluid boils in the callipers. You should understand that brakes have faded when you experience any of the following:
- It takes a while before the brakes kick in.
- The pedal depresses completely.
- A burning odour is emitted from the brakes.
- In extreme cases where the brakes have faded completely they can emit smoke or worse, catch fire.
When brakes begin to fade you should drive at lower speeds and try to use them only when required until you get the braking system repaired or replaced.
Previously, brake pads were made from Asbestos type material that were quite efficient at resisting heat. But there was a major drawback of this material and this was the excess production of dust. Also there were many gases that were produced by asbestos pads during braking and this was another reason why car manufacturers were on the lookout for a better material for brake pads. These gases could interfere with contact of brake pads with brake disc and to prevent this holes were cross-drilled into the discs.
However, there is a big issue that drilled rotors face and this is known as stress cracking. In order to prevent stress cracking, slots were created that promoted cooling and prevented gas from building up. Improved ventilation system along with replacement of asbestos pads led to the production of a highly efficient braking system.
The brake pads that are in use today are made up of materials that are safe for the environment thus making the latest braking technology more eco-friendly than their earlier generations. However, these brakes have their own disadvantage that they cause premature warping of brake discs that causes a pulsing feel in the brake pedal. It is a good idea to get your brakes checked when you take your car for a service.
High Performance Brake Pads
There is a variety of requirements that must be met by brake pads so that they can handle the everyday wear and tear that they are subjected to:
- Steady performance even in wet conditions
- Low squeal and noise
- Low production of dust
High performance brake pads that are specially designed nowadays are capable of resisting high temperatures and do not fade easily despite high heat build-up. The only disadvantage of this braking system is that they are not equally efficient at braking in low temperatures. It is not a good idea to use racing pads on the street as they can never achieve the operating temperature that they are capable of withstanding.
Change your fluid
Brake fluid is susceptible to moisture and this can have a negative impact on the braking ability of the system.
- The addition of moisture in the brake fluid lowers its boiling point. This increases the possibility of brake fluid boiling when heavy braking is used.
- Brake fading becomes easier due to boiling of brake fluid and the fading accelerates when the vehicle is being driven downhill where frequent braking is required.
- Moisture also leads to corrosion of metal components that are used in the braking system and this can lead to breakdown of braking system.
This problem can sound severe but the solution is simple. You only need to change the brake fluid from time to time to prevent the above problems from occurring. The frequency of servicing and changing fluid is usually specified by the vehicle manufacturer in the owner’s manual. If the vehicle is being used very frequently then you may have to change it more often.
Keeping the brakes happy
The best indication of a well maintained car is its ability to apply brakes. Larger brake discs and higher quality brake pads are available for those who wish to take their car to the track. However, it is important to remember that not every braking system is suitable for a given type of environment. A braking system that is good at braking in a high temperature environment may not be equally effective in a wet environment. By regularly changing your brake fluid and making the right choices your brakes should perform without a flaw.
Dealing with Brake Failure
People with bad driving habits often do not maintain their brakes well. An inevitable and unavoidable situation awaits them and it goes by the name of brake failure. With the advancements that have taken place in the braking technology in recent times a person is more likely to be hit by a lightning than experience a sudden failure of brakes.
This makes it necessary for you to check the brakes each time you get behind the steering wheel. This is a test that you can perform on your way to office or college without having to include it in your clustered to-do list. There are two types of checks that you can perform to get yourself acquainted with the condition of brakes and these are the static and rolling brake tests.
Static brake test
Most of us panic at the mention of the word test as we think there is a lot of analysis and learning involved. However, tests of these kinds are such that anybody with a driving experience of few months can perform. The static brake test involves pressing the brake pedal as soon as you get into your car. If you feel some resistance from the pedal then your brakes are in the right condition.
However, if the pedal gets depressed completely to the floor without offering any resistance then your brakes may be in deteriorating condition or may have already deteriorated. In such cases it is possible that the fluid may have leaked or brake pads need replacement. Whatever the reason may be, it is not safe to drive such a vehicle.
Rolling Brake Test
This is not a test that can be performed on a stationary car. To properly perform this test, the car should be at low speeds of five to ten miles an hour. At such a speed you should apply the brakes to see if they are effective at braking. If the car comes to a halt instantly then your brakes are in good condition. However if the brakes take long to get applied then you may need to get the brakes checked.
Symptoms of impending brake failure
It is the inherent nature of every machine to give warning signs before a system breakdown. Brakes are not any different and give many signals when there is an impending brake failure. Most of the brakes that are used nowadays are hydraulic brakes that make use of a fluid to work effectively. It is necessary that the hydraulic pipes have the optimum level of fluids and any sudden change in fluid levels due to fluid leaks should be easily noticeable. The most common sign of a fluid leak is the brake pedal becoming softer and having a spongy feel to it.
Total brake Failure
Even though total brake failure is extremely rare there are instances when it has happened. In 2010 automobile industry giants Chrysler, Volvo, Honda and Toyota had recalled many vehicles that they believed were at a risk of brake failure.
As you must be aware every car comes with two types of braking systems. The main braking system is usually a hydraulic brake system while the other braking system is the handbrake. In case the main braking system suffers a breakdown you should bring the vehicle to a halt using the handbrake.
Most people already know how to apply the handbrake but for those who are not aware of it, you need to keep the release button on the brake handle pressed as you apply the brake. However, an important point to be remembered is that a handbrake is ineffective if the vehicle is over the speed of 40 mph or engaged in higher gears.
Engines dominate most of our conversations about a car. Performance is like the lead actor of a film who takes away most of the attention but safety is like the crew behind the silver screen, something that we often take for granted and rarely acknowledge. This blog has been written with the intention to highlight the importance of brakes and the steps that need to be taken to ensure that you are safe on the roads.