Drivers Fact Sheets
Understanding Braking Systems
Braking is a useful skill to master for safety’s sake. Increasingly, over the last thirty years, new technologies have been introduced to assist the driver when he needs to brake quickly. These braking systems have saved many lives.
Antilock Brake Systems
Antilock Braking Systems (ABS) is a form of electronic braking which was invented to help a driver control a vehicle under heavy braking by preventing the wheels from locking up. ABS is a marvelous invention, it allows you to both slow down and steer at the same time. All you have to do is hit the brakes hard and watch as you gracefully come to a halt.
ABS was first introduced in cars in 1978, and the technology now is far more advanced than when initially launched. For many years it was possible to slow down faster using manual braking techniques. Today, however, in many real world conditions ABS both prevents wheels from locking and also slows you down quicker than any manual braking technique, especially on wet or slippery roads.
How They Work
Braking systems take the force applied to the foot pedal by the driver and transfer it via a mechanical system to the brakes on the wheel. The mechanism works by increasing the input force via a servo to the master cylinder, which converts the force into the pressure applied by brakes. The master cylinder has two pressure chambers both of which are responsible for the braking pressure on two of the wheels and this is to provide an extra level of safety should there be a failure.
During this process there is a chance that the wheels stop rotating before the car comes to a halt. This process is known as ‘locking up’ and means that the braking force on the wheel is not being transferred efficiently to stop the vehicle due to the fact that the tyre is sliding upon the road.
This leads to a longer stopping distance than if the wheel had not locked because there is reduced grip between the car and the road, which in turn leads to an increased chance of losing control of the vehicle and skidding.
On vehicles without ABS the best method to regain control of the vehicle is to ‘pump’ the brakes by taking your foot off the pedal and reapplying it. This allows the tyres to regain traction upon the road, rather than skid over the surface of it.
Antilock Braking System
ABS works in a similar but much more effective manner. Electric sensors monitor the speed of the wheel as it rotates and detect if it is about to lock up under braking. When this happens the brakes are automatically released and then rapidly reapplied. This process occurs several times to prevent a skid and to ensure that a vehicle can be steered by the driver to avoid a collision.
The Advantages Of ABS
Although the ABS will not decrease a vehicle’s stopping distance compared to an identical vehicle without ABS, it ensures that the shortest distance in which a vehicle can be brought to rest is achieved. It is particularly effective in doing this on surfaces which are wet or icy upon which a vehicle is much more likely to skid.
The main benefit of ABS is the control that a driver has over the vehicle’s steering. In an emergency the driver of a vehicle equipped with ABS will have a better chance of steering around the obstacle due to the reduced risk of skidding.
Brake Assist (BA) is a new technology that ensures that the maximum pressure is applied by the brakes to stop a vehicle in an emergency situation. Some manufacturers also refer to the same system as Emergency Brake Assist (EBA).
How It Works And Its Advantages
When a driver makes an emergency stop the brake pedal has to be pressed, the more pressure applied to the brake pedal, the greater the pressure through the braking system, which is amplified and provided to the brake. In some cases a driver might fail to respond to a hazard up ahead as well as possible and fail to depress the brake pedal fully, meaning that the full pressure of the braking system is not being applied to the wheels.
Brake Assist detects how quickly the pedal is depressed to judge whether the driver wanted to perform an emergency-braking manoeuvre. If it concludes that the situation is an emergency and the pedal isn’t depressed fully then it will increase the hydraulic pressure in the braking system to make up the gap.
If the driver successfully avoids the danger and removes or reduces the force on the pedal then the system will also reduce its involvement.
Brake Assist And Your Vehicle
The system will not reduce the stopping distance of the car, but it will make sure that the car is stopped in the shortest distance that it potentially could by compensating for any hesitancy in applying the brakes hard in an emergency situation.
Brake Assist is based on the ABS technology of a vehicle and will not be found on a vehicle without ABS. It should not change how drivers respond to an emergency – you should still brake as hard as possible.
Like all braking systems on a vehicle, it is safest to never get into an emergency situation where you need to use them. The best way of doing this is to ensure there is at least a two second gap between yourself and the vehicle in-front, and to drive at a speed suitable for the conditions.
Electronic Stability Control
The Electronic Stability Control (ESC) is a further evolution of electronic braking technology such as ABS and also uses other systems such as traction control. It is intended as a way of correcting situations in which a driver has made an error by stabilising the vehicle quickly so as not to make any dangerous situations worse.
It will work in circumstances where steering is needed in order to turn the vehicle more effectively so as to provide a decreased risk of skid or loss of control.
Other Names For ESC
Different manufacturers use systems designed to achieve the same results in the same way but have used different names. The following systems used by different manufacturers are equivalent to ESC:
- Electronic Stability Program (ESP)
- Dynamic Stability Control (DSC)
- Vehicle Stability Control Systems (VSCS)
How It Works And Its Advantages
There are many situations where a vehicle could lose grip with the road, for example; entering a corner too fast, losing control of the vehicle due to an inappropriate driving speed for the conditions, and after steering sharply to avoid an unexpected obstacle.
In order to detect a problem of this nature, the Electronic Stability Control works by monitoring the position of the steering wheel and comparing it with the direction that the car is heading. The ESC then works out the extent of the problem, it can calculate the speed of the tyres using the sensors which are already present as part of the ABS. The forces which are changing the vehicles heading can then be computed, for example the rotation of the car around its centre of gravity or the forces acting to push it out of line on a bend.
The system then restores the stability and control of the vehicle, by reducing the engine power to slow the car down, and braking individual wheels to rotate the car to face the direction wanted by the driver.
Electronic Stability Control And Your vehicle
You should find out from your driver’s handbook if your car has a form of EPS and how it communicates with you that it is working when you start the car. If you are hiring a car you should enquire if it has stability control.
Electronic Stability Controls and other equivalent systems are designed to compensate for driver misjudgements and aid in keeping control of the vehicle during emergency manoeuvres. It cannot prevent all accidents involving skids and relies on the driver knowing the correct speed and behaving appropriately to the road conditions.
Forward Collision Warning Systems
Not strictly braking systems, but they can incorporate automatic braking in the system, taking away the delay a driver may experience in adjusting to a potential accident.
Forward Collision Warning is a system for visual and audible warning on the objects or vehicles in front of a vehicle. Using radar and laser sensors it can detect an imminent crash and reduce the severity of an accident. Depending on the system they may warn the driver, precharge the brakes, inflate seats for extra support, move the passenger seat, position head rests to avoid whip lash, tension seat belts and automatically apply partial or full braking to minimize impact.
Even though drivers can see what is in front of their vehicle, they can easily overestimate the distance between vehicles. These systems can assist the driver in finding the safe distance. The status will change from ‘safe’ to ‘critical’ as the distance decreases.
What Difference Will They Make?
Time to Contact (TTC) is the key technique used in the Forward Collision Warning, which detects whether a collision is imminent or not. The system examines the speed of host vehicle, relative speed and relative acceleration by learning the variation in size of the image of the vehicle in front. Consequently, the driver will be warned of the dangers. It can work in conjunction with Collision Mitigation by Braking (CMB) technology which detects moving and stationary objects, offering brake assist support across a full range of speeds. In case of an imminent collision, automatic braking is triggered.
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