Seat belt research paper

INTRODUCTION
Contents:
  1. Accessibility links
  2. Effectiveness of Ford’s belt reminder system in increasing seat belt use | Injury Prevention
  3. Seat Belts Argumentative Essay
  4. Seat Belts
  5. Working Papers & Publications

The world's first seat belt law was put in place in , in the state of Victoria, Australia , making the wearing of a seat belt compulsory for drivers and front-seat passengers.

Accessibility links

This legislation was enacted after trialing Hemco seatbelts, designed by Desmond Hemphill — , in the front seats of police vehicles, lowering the incidence of officer injury and death. A 2-point belt attaches at its two endpoints. A simple strap was first used March 12, by pilot Benjamin Foulois , [14] [15] [16] a pioneering aviator with the Aeronautical Division, U.

Signal Corps , so he might remain at the controls during turbulence. A lap belt is a strap that goes over the waist. This was the most commonly type of belt prior to legislation requiring three-point belts, and is found in older cars. Coaches are equipped with lap belts although many newer coaches have three-point belts , as are passenger aircraft seats.

University of Minnesota Professor James J. Crash Ryan was the inventor of and held the patent on the automatic retractable lap safety belt. Ralph Nader cited Ryan's work in Unsafe at Any Speed and in President Lyndon Johnson signed two bills requiring safety belts in all passenger vehicles starting in Until the s, three-point belts were commonly available only in the front outboard seats of cars; the back seats were only often fitted with lap belts.

Evidence of the potential of lap belts to cause separation of the lumbar vertebrae and the sometimes associated paralysis , or " seat belt syndrome, " led to progressive revision of passenger safety regulations in nearly all developed countries to require three-point belts first in all outboard seating positions and eventually in all seating positions in passenger vehicles. Since September 1, , all new cars sold in the U.


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A "sash" or shoulder harness is a strap that goes diagonally over the vehicle occupant's outboard shoulder and is buckled inboard of his or her lap. The shoulder harness may attach to the lap belt tongue, or it may have a tongue and buckle completely separate from those of the lap belt.

Shoulder harnesses of this separate or semi-separate type were installed in conjunction with lap belts in the outboard front seating positions of many vehicles in the North American market starting at the inception of the shoulder belt requirement of the U. However, if the shoulder strap is used without the lap belt, the vehicle occupant is likely to "submarine", or slide forward in the seat and out from under the belt, in a frontal collision.

In the mids, three-point belt systems such as Chrysler's "Uni-Belt" began to supplant the separate lap and shoulder belts in American-made cars, though such three-point belts had already been supplied in European vehicles such as Volvo , Mercedes-Benz , and Saab for some years. A three-point belt is a Y-shaped arrangement, similar to the separate lap and sash belts, but unitized. Like the separate lap-and-sash belt, in a collision the three-point belt spreads out the energy of the moving body over the chest, pelvis, and shoulders.

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Effectiveness of Ford’s belt reminder system in increasing seat belt use | Injury Prevention

Volvo introduced the first production three-point belt in However, the first car model to have the three-point seat belt as a standard item was the Volvo , first outfitted with a two-point belt at initial delivery in , replaced with the three-point seat belt the following year. The Belt-in-Seat BIS is a three-point harness with the shoulder belt attached to the seat itself, rather than to the vehicle structure. The first car using this system was the Range Rover Classic. Fitment was standard on the front seats from A General Motors assessment concluded seat-mounted three-point belts offer better protection especially to smaller vehicle occupants, [26] though GM did not find a safety performance improvement in vehicles with seat-mounted belts versus belts mounted to the vehicle body.

BIS type belts have been used by automakers in convertibles and pillarless hardtops, where there is no "B" pillar to affix the upper mount of the belt. Chrysler and Cadillac are well known for using this design. Antique auto enthusiasts sometimes replace original seats in their cars with BIS-equipped front seats, providing a measure of safety not available when these cars were new.

However, modern BIS systems typically use electronics that must be installed and connected with the seats and the vehicle's electrical system in order to function properly. 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. A 4-point harness is similar, but without the strap between the legs, while a 6-point harness has two belts between the legs. In NASCAR , the 6-point harness became popular after the death of Dale Earnhardt , who was wearing a five-point harness when he suffered his fatal crash; as it was first thought that his belt had broken, and broke his neck at impact, some teams ordered a six-point harness in response.


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Aerobatic aircraft frequently use a combination harness consisting of a five-point harness with a redundant lap-belt attached to a different part of the aircraft. While providing redundancy for negative-g manoeuvres which lift the pilot out of the seat ; they also require the pilot to un-latch two harnesses if it is necessary to parachute from a failed aircraft. Seatbelt airbags are available in some models of Ford and Mercedes. The purpose of locking retractors is to provide the seated occupant the convenience of some free movement of the upper torso within the compartment, while providing a method of limiting this movement in the event of a crash.

Most modern seat belts are stowed on spring-loaded reels called "retractors" equipped with inertial locking mechanisms that stop the belt from extending off the reel during severe deceleration.

Seat Belts Argumentative Essay

There are two main types of inertial seat belt lock. A webbing-sensitive lock is based on a centrifugal clutch activated by rapid acceleration of the strap webbing from the reel. The belt can be pulled from the reel only slowly and gradually, as when the occupant extends the belt to fasten it. A sudden rapid pull of the belt—as in a sudden braking or collision event—causes the reel to lock, restraining the occupant in position. A vehicle-sensitive lock is based on a pendulum swung away from its plumb position by rapid deceleration or rollover of the vehicle.

In the absence of rapid deceleration or rollover, the reel is unlocked and the belt strap may be pulled from the reel against the spring tension of the reel.

Seat Belts

The vehicle occupant can move around with relative freedom while the spring tension of the reel keeps the belt taut against the occupant. When the pendulum swings away from its normal plumb position due to sudden deceleration or rollover, a pawl is engaged, the reel locks and the strap restrains the belted occupant in position. Dual-sensing locking retractors use both vehicle G-loading and webbing payout rate to initiate the locking mechanism.

Seatbelts in many newer vehicles are also equipped with "pretensioners" or "web clamps", or both.

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Pretensioners preemptively tighten the belt to prevent the occupant from jerking forward in a crash. Mercedes-Benz first introduced pretensioners on the S-Class. In the event of a crash, a pretensioner will tighten the belt almost instantaneously. This reduces the motion of the occupant in a violent crash. Like airbags, pretensioners are triggered by sensors in the car's body, and many pretensioners have used explosively expanding gas to drive a piston that retracts the belt.

Pretensioners also lower the risk of "submarining", which occurs when a passenger slides forward under a loosely fitted seat belt. Some systems also pre-emptively tighten the belt during fast accelerations and strong decelerations, even if no crash has happened. This has the advantage that it may help prevent the driver from sliding out of position during violent evasive maneuvers, which could cause loss of control of the vehicle. These pre-emptive safety systems may prevent some collisions from happening, as well as reducing injury in the event an actual collision occurs.

Webclamps clamp the webbing in the event of an accident, and limit the distance the webbing can spool out caused by the unused webbing tightening on the central drum of the mechanism. These belts also often incorporate an energy management loop "rip stitching" in which a section of the webbing is looped and stitched with a special stitching. The function of this is to "rip" at a predetermined load, which reduces the maximum force transmitted through the belt to the occupant during a violent collision, reducing injuries to the occupant.

A study demonstrated that standard automotive three-point restraints fitted with pyrotechnic or electric pretensioners were not able to eliminate all interior passenger compartment head strikes in rollover test conditions. When a crash occurs the bladder inflates with a gas to increase the area of the restraint contacting the occupant and also shortening the length of the restraint to tighten the belt around the occupant, improving the protection.

The system supports the head during the crash better than a web only belt. It also provides side impact protection. In , Ford began offering rear seat inflatable seat belts on a limited set of models, such as the Explorer and Flex. In , Volkswagen announced they had a functional passive seat belt. Automatic seat belts received a boost in the United States in when Brock Adams , United States Secretary of Transportation in the Carter Administration , mandated that by every new car should have either airbags or automatic seat belts.

General Motors introduced a three-point non-motorized passive belt system in to comply with the passive restraint requirement. A study released in by the United States Department of Transportation said that cars with automatic seat belts had a fatality rate of. In , Drew Lewis , the first Transportation Secretary of the Reagan Administration , influenced by studies done by the auto industry, [48] dropped the mandate; [49] the decision was overruled in a federal appeals court the following year, [50] and then by the Supreme Court. When driver side airbags became mandatory on all passenger vehicles in model year , most manufacturers stopped equipping cars with automatic seat belts.

Automatic belt systems generally offer inferior occupant crash protection. In such a scenario, the occupant may be thrown from the vehicle and suffer greater injury or death. Because many automatic belt system designs compliant with the US passive-restraint mandate did not meet the safety performance requirements of Canada —which were not weakened to accommodate automatic belts—vehicle models which had been eligible for easy importation in either direction across the US-Canada border when equipped with manual belts became ineligible for importation in either direction once the U.

The Physics of Seat Belts

Two particular models included the Dodge Spirit and Plymouth Acclaim. Automatic belt systems also present several operational disadvantages. Motorists who would normally wear seat belts must still fasten the manual lap belt, thus rendering redundant the automation of the shoulder belt. Those who do not fasten the lap belt wind up inadequately protected only by the shoulder belt; in a crash without a lap belt such a vehicle occupant is likely to "submarine" be thrown forward under the shoulder belt and be seriously injured.

Vehicle owners tend to disconnect the motorized or door-affixed shoulder belt to relieve the nuisance of entering and exiting the vehicle, leaving only a lap belt for crash protection.

Working Papers & Publications

Starting in and ending in , the United States conducted a research project on seat belt effectiveness on a total of 40, vehicle occupants using car accident reports collected during that time. A study as part of this program used data taken from 15, tow-away accidents that involved only car models made between and The study also concluded that the effectiveness of the safety belt did not differ with size of car.

The NCAP is a government program that evaluates vehicle safety designs and sets standards for foreign and domestic automobile companies. The agency developed a rating system and requires access to safety test results. Research and development efforts are ongoing to improve the safety performance of vehicle seatbelts. Some experimental designs include:. In as a package , Ford offered lap only seat belts in the rear seats as an option within the Lifeguard safety package.

In , Volvo started to install lap belts in the rear seats.