Seatbelts Essay

330 Words2 Pages
A Seat Belt, or sometimes known as a ‘Safety Belt’, is a harness that is designed to secure the occupant of a car in the event of a crash. The belt will stop the occupant suffering injuries from the extreme forces that would be caused by sudden braking or a collision. Seat Belts are designed to reduce injuries by stopping passengers from being thrown into hard objects contained within the car, such as the dash or steering wheel, or at higher speeds, to save the passenger from being thrown from the car completely. There are many different types of seatbelts, some more safe and reliable than others. The first type of seatbelt that was found in cars on a large scale was the Lap Belt. As diagram A shows, a lap belt is an adjustable strap that goes over a person’s waist. They are found in older cars, the middle back seat in some cars and in passenger aircraft. The Lap Belt was found to be ineffective because at high speeds passengers would suffer from spinal injuries, such as separation of the lumbar vertebrae, because of the belt. The most common seat belt that is found today is the Three-point Belt. Diagram B, shows that the belt is a single belt that goes over the passenger’s chest and waist, and has three points of contact with the car. The three-point belt is very effective because it spreads the force of the crash over the shoulder, chest, waist and pelvis evenly. Most seat belts are equipped with locking mechanisms that tighten the belt when pulled hard, by the force of a passenger's body during a crash for example, but do not tighten when pulled slowly. This is implemented with a centrifugal clutch, which engages as the reel spins quickly. Alternatively, they may also be secured by a weighted pendulum or ball bearing which when deflected by deceleration or a rollover lock on to the
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