Facts about Seat Belts
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Seat belts were
first invented by George Cayley in the 1800s. Seat belts were
introduced in aircraft in the 1930s. The automotive seat belt was
introduced into the United States by Kenneth Ligon and his
brother, Bob Ligon, whose patented quick release seat belt, the
AutoCrat Safety Belt, was the first seat belt installed as
original equipment in the US by Ford in its 1956 model year. The
first seatbelt to be included as standard was on the 1959 Volvo.
However, they were not required by law in the US on passenger
vehicles until the 1968 model year.
Three point harnesses were first made readily available in
mass-produced vehicles by Volvo. It was Swedish engineer Nils
Bohlin who patented the modern three-point belt design and gave it
harnesses are similar to the lap and sash seat belts, but with one
single continuous length of webbing. Three-point seat belts help
spread out the energy of the moving body in a collision over the
chest, pelvis, and shoulders. Until the 1970's three-point belts
were commonly available only in the front seats of cars, the back
seats having only lap belts. Evidence of the potential for lap
belts to cause separation of the lumbar vertebrae and the
sometimes associated paralysis, or "seat belt syndrome", has led
to a revision of safety regulations in nearly all of the developed
world requiring that all seats in a vehicle be equipped with
three-point seat belts.
Most seat belts are
equipped with locking mechanisms that tighten the belt when pulled
hard (e.g. by the force of a passenger's body during a crash) but
do not tighten when pulled slowly. Many are also equipped with 'pretensioners',
which preemptively tighten the belt to prevent the passenger from
jerking forward in a crash.