Types

Two-pointedit

A 2-point belt attaches at its two endpoints. A simple strap was first used March 12, 1910 by pilot Benjamin Foulois, a pioneering aviator with the Aeronautical Division, U.S. Signal Corps, so he might remain at the controls during turbulence.

The Irvin Air Chute Company made the seat belt for use by professional race car driver Barney Oldfield when his team decided the daredevil should have a "safety harness" for the 1923 Indianapolis 500.

Lapedit

A lap belt is a strap that goes over the waist. This was the most common 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 1966, President Lyndon Johnson signed two bills requiring safety belts in all passenger vehicles starting in 1968.

Until the 1980s, 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 the 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, 2007, all new cars sold in the US require a lap and shoulder belt in the center rear seat. Besides regulatory changes, "seat belt syndrome" has led to tremendous liability for vehicle manufacturers. One Los Angeles case resulted in a $45 million jury verdict against Ford; the resulting $30 million judgment (after deductions for another defendant who settled prior to trial) was affirmed on appeal in 2006.

Sashedit

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 US National Highway Traffic Safety Administration's (NHTSA) Federal Motor Vehicle Safety Standard 208 on 1 January 1968. 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 mid-1970s, 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.

Three-pointedit

A three-point belt is a Y-shaped arrangement, similar to the separate lap and sash belts, but unified. 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. Volvo introduced the first production three-point belt in 1959. The first car with a three-point belt was a Volvo PV 544 that was delivered to a dealer in Kristianstad on August 13, 1959. However, the first car model to have the three-point seat belt as a standard item was the 1959 Volvo 122, first outfitted with a two-point belt at initial delivery in 1958, replaced with the three-point seat belt the following year. The three-point belt was developed by Nils Bohlin who had earlier also worked on ejection seats at Saab. Volvo then made the new seat belt design patent open in the interest of safety and made it available to other car manufacturers for free.

Belt-in-Seatedit

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, which offered BIS as standard on the front seats from 1970. Some cars like the Renault Vel Satis use this system for the front seats. A General Motors assessment concluded seat-mounted three-point belts offer better protection especially to smaller vehicle occupants, 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.citation needed

4-, 5-, and 6-pointedit

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.

Seven-pointedit

Aerobatic aircraft frequently uses 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 maneuvers (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 airbagedit

Seatbelt airbags are available in some models of Ford and Mercedes.