Seat belts were invented by George Cayley in the early 19th century, though Edward J. Claghorn of New York, New York was granted the first patent (U.S. Patent 312,085, on February 10, 1885 for a safety belt).Claghorn was granted United States Patent #312,085 for a Safety-Belt for tourists, painters, fireman, etc. who are being raised or lowered, described in the patent as "designed to be applied to the person, and provided with hooks and other attachments for securing the person to a fixed object."
The Purpose Of Seat Belts :-
Seat belts are designed to retain people in their seats, and so prevent or reduce injuries suffered in a crash. They ensure that as little contact is made between the occupant and vehicle interior as possible and significantly reduce the risk of being thrown from a vehicle. On modern vehicles, seat belts are now also designed to work as the key part of wider injury prevention measures and safety systems, such as airbags and head restraints, which will not be as effective in reducing the risk of injury if an occupant is not wearing a seat belt.
Seat Belt Design :-
This section describes the main elements of seat-belt design. Seat-belt designs should comply with national or international standards (covered in Module 3 of the manual). Designs that ensure easy of use will serve to increase wearing rates.
1. Lap ( 2 Point) :
An adjustable strap that goes over the waist. This type of belt is frequently found in older cars, and has been used, until recently, on some newer vehicles in rear or rear middle seats. These types of belt are also found on some coaches.
2. Sash :
An adjustable strap that goes over the shoulder. Used mainly in vehicles during the 1960(1959), however they had limited benefit because it was very easy to slip out of them in a collision.
3. Three Point Lap And Diagonal Seat Belt :
Rated highly for effectiveness and ease of use, the three-point lap and diagonal seat-belt is the most commonly used in cars, vans, minibuses and trucks and in the driver’s seat of buses and coaches. The seat-belt tongue clips into the buckle, which in the front seats of cars is usually placed on the end of a stiff stalk or directly attached to the seat. This system allows the occupant to connect the tongue and buckle using one hand, preventing ejection after maintaining.
4. Belt In Seat (BIS) :
The BIS is a three-point where the shoulder belt attachment is to the backrest, not to the b pillar. The first car using this system in the United States was the 1990 Mercedes-Benz SL. Some car like a Renault use this system for the front seat. This system allegedly is safer in case of rollover, especially with 4-8 years old, though other sources dispute this claim.
5. Five Point Harness :
These restraints are safer but more restrictive than most other seat belt types. Five-point harnesses are typically found in child safety seats and in racing cars. The lap portion is connected to a belt between the legs and there are two shoulder belts, making a total of five
points of attachment to the seat. (Strictly speaking, harnesses are never to be fastened to the seat—they should be fastened to the frame/sub-frame of the automobile.)
These harnesses are similar to a five-point harness but include an extra belt between the legs, which is seen by some to be a weaker point than the other parts. These belts are used mainly in racing. In NASCAR, the six-point harness became popular after the death of Dale Earnhardt. Earnhardt was wearing a five-point harness when he suffered his fatal crash. As it was first thought that his belt had broken, some teams ordered a six-point harness in response.
Types Of Seat Belts Pretensioners :-
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Seatbelt pretensioners are a component of the seatbelt system which locks the seatbelt in place during a crash. There are three types of seatbelt pretensioner: mechanical, electrical, and pyrotechnic.
1. Mechanical Pretensioner :
The mechanical pretensioner consists of an inertial wheel combined with a pendulum which moves to lock the belt into place during sudden deceleration. Most drivers have experienced the frustration of pulling a seatbelt from its reel only to have it lock unexpectedly or to be driving down the road and experience the seatbelt gradually getting tighter and tighter. This is the action of the mechanical pretensioner at work.
2. Electric Pretensioner :
The electric pretensioner replaces the pendulum with an electrical sensor. This prevents the false locking condition that is commonly observed with a mechanical pretensioner. The electrical sensor can also be interconnected with other systems on the vehicle, such as rollover sensors or airbag sensors. This connectivity ensures that the seatbelts will lock even if the sudden deceleration that is needed to lock a mechanical pretensioner does not occur.
3. Pyrotechnic Pretensioner :
The pyrotechnic pretensioner is the most sophisticated type of pretensioning device. The electronically triggered pyrotechnic device not only locks the seatbelt in place but tightens the belt to take up any slack that may be present, minimizing the movement of the occupant within the vehicle during a crash situation. Once a pyrotechnical pretensioner is activated it must be replaced.
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