Friday, 1 July 2011

Safety Features In Cars


Safety Features In Cars


Antilock Brake System
An antilock brake system (ABS) prevents a vehicle’s wheels from locking during “panic” braking, which allows the driver to maintain greater steering control — a key factor in avoiding a collision. However, an ABS does not guarantee your ability to avoid a crash. Furthermore, you still may lose control when driving at excessive speeds or when using extreme steering maneuvers. Learning to use the ABS correctly will provide you with the greatest benefit from the system.
All passenger cars equipped with ABS have four-wheel ABS. Sport utility vehicles, trucks, and vans equipped with ABS can have either four-wheel or two-wheel ABS. Four-wheel ABS monitor and control all the wheels of the vehicle, while two-wheel ABS only monitor and control the rear wheels of a vehicle.
Some ABS’s also include brake assist, which senses emergency braking by detecting the speed or force at which the driver presses the brake pedal and boosts the power as needed. Under certain conditions, brake assist may reach the braking force needed to activate the ABS more quickly and easily compared with vehicles without brake assist, and can potentially reduce overall stopping distance by eliminating the delay caused by not braking hard enough or soon enough.
Crumple Zones
Crumple zones work by managing crash energy, absorbing it within the outer parts of the vehicle, rather than being directly transmitted to the occupants, while also preventing intrusion into or deformation of the passenger cabin. This better protects car occupants against injury. This is achieved by controlled weakening of sacrificial outer parts of the car, while strengthening and increasing the rigidity of the inner part of the body of the car, making the passenger cabin into a 'safety cell', by using more reinforcing beams and higher strength steels. Impact energy that does reach the 'safety cell', is spread over as wide an area as possible to reduce its deformation. Volvo introduced the side crumple zone, with the introduction of the SIPS (Side Impact Protection System) in the early 1990s.
When a vehicle and all its contents, including passengers and luggage are travelling at speed, they have inertia which means that they will want to continue forward with that direction and speed (Newton's first law of motion).[10] In the event of a sudden deceleration of a rigid framed vehicle due to impact, unrestrained vehicle contents will continue forwards at their previous speed due to inertia, and impact the vehicle interior, with a force equivalent to many times their normal weight due to gravity. The purpose of crumple zones is to slow down the collision and to absorb energy, to reduce the difference in speeds between the vehicle and its occupants.
Seatbelts
Seatbelts restrain the passengers so they don't fly through the windshield, and are in the correct position for the airbag and also spread the loading of impact on the body. Seat belts also absorb passenger inertial energy by being designed to stretch during an impact, again to reduce the speed differential between the passenger's body and their vehicle interior. In short: A passenger whose body is decelerated more slowly due to the crumple zone (and other devices) over a longer time, survives much more often than a passenger whose body indirectly impacts a hard, undamaged metal car body which has come to a halt nearly instantaneously. It is like the difference between slamming someone into a wall headfirst (fracturing their skull) and shoulder-first (bruising their flesh slightly) is that the arm, being softer, has tens of times longer to slow its speed, yielding a little at a time, than the hard skull, which isn't in contact with the wall until it has to deal with extremely high pressures.

In the event of a crash, seat belts are designed to keep you inside the vehicle. They also reduce the risk that you will collide with the steering wheel, dashboard, or windshield. New seat belt designs have the following additional features that improve seat belt performance:
Adjustable upper belts. An adjustable upper belt lets you change the position of the shoulder strap to accommodate a person’s size. This feature may encourage passengers to wear their belts, since it increases shoulder belt comfort.
Seat belt pretensioner. Pretensioners retract the seat belt to remove excess slack, almost instantly, in a crash. However, you still need to adjust your seat belt so that it fits as snugly as possible, since pretensioners are not powerful enough to pull you back into your seat in the event of an impact.
Energy management features. Energy management features allow seat belts to “give” or yield during a severe crash to prevent forces on the shoulder belt from concentrating too much energy on your chest. These features include “load limiters” built into the shoulder belt retractor and/or “tear stitching” in the webbing that causes the seat belt to extend gradually.
Rear center seat lap/shoulder belts. Some manufacturers provide a rear center lap/shoulder belt. This added feature is especially beneficial to older children and children in booster seats who are often seated in the rear center position.

Head Injury Protection
Head injury protection consists of foam or other energy absorbing material under the trim of the vehicle interior and is likely to be invisible to vehicle occupants. Some vehicles have head air bags. While all head air bags are designed to deploy in side impacts, some are also designed to deploy during rollovers. Both types of air bags are designed to help protect occupants from injuries caused when their head strikes the upper interior of a vehicle.


Head Restraints
Head restraints are extensions of the vehicle’s seats that limit head movement during a rear-impact crash, thus, reducing the probability of neck injury. Head restraints meeting specific size and strength requirements are required in front seats, but not in rear seats. While you must adjust most head restraints manually, some adjust automatically with changes in seat position or dynamically in a crash. In general, dynamic head restraints provide the best protection.

Traction Control
Traction control systems improve vehicle stability by controlling the amount the drive wheels can slip when you apply excess power. The system automatically adjusts the engine power output and, in some systems, applies braking force to selected wheels during acceleration. Traction control is mainly found in vehicles with four-wheel antilock brake systems.

All-Wheel Drive
All-wheel drive distributes power to both front and rear wheels to maximize traction. Unless combined with traction control, all-wheel drive systems do not prevent the drive wheels from slipping when you apply excess power during acceleration.

Electronic Stability Control
Electronic stability control (which is offered under various trade names) is designed to assist drivers in maintaining control of their vehicles during extreme steering maneuvers. Electronic stability control senses when a vehicle is starting to spin out (oversteer) or plow out (understeer), and it automatically applies the brake to a single wheel. It is intended to reduce the occurrence of crashes in which vehicles veer off the road and strike curbs, soft shoulders, guard rails and other objects that initiate rollovers. However, it can’t keep a vehicle on the road if its speed is simply too great for the curve and the available traction.

Weight
Crash data show that heavy vehicles offer more protection than light vehicles with the same safety equipment, particularly in two-vehicle crashes.
Overview
A car safety features is crucial for ones safety.