What is a Seatbelt made of?
What is a Seatbelt made of?
Woven polyester webbing designed to stretch a controlled amount, plus a locking retractor and a pyrotechnic pretensioner.
The three-point belt was designed by Nils Bohlin at Volvo in 1959, and Volvo made the patent freely available on the grounds that it was worth more as a safety standard than as a commercial advantage. Everything since has been about managing the force curve rather than making the belt stronger: the pretensioner removes slack, the load limiter caps the peak, and the airbag catches the head that the belt cannot restrain. A belt that has been in a serious crash is replaced rather than reused, because the pretensioner has fired and the webbing has already used its stretch. Bleach, solvents and dye also destroy webbing strength invisibly, which is why the advice is to clean belts with mild soap and water only.
Component by component
| Part | Material | Why that material |
|---|---|---|
| webbing | woven polyester yarn, about 46-48 mm wide | Polyester holds its strength when wet and resists ultraviolet far better than the nylon that was originally used. |
| designed stretch | weave geometry that allows a few per cent elongation under load | A completely inextensible belt would transfer the whole deceleration to the ribcage; controlled stretch spreads the load over more milliseconds. |
| retractor | spring-loaded spool with an inertial pawl locking mechanism | It locks on sudden webbing pull or vehicle deceleration, which is why the belt lets you lean forward slowly but not quickly. |
| pretensioner | a small pyrotechnic gas generator or a wound spring device | It fires with the airbags and pulls several centimetres of slack out before the occupant starts moving forward. |
| load limiter | a torsion bar in the retractor spool | Above a set force the bar twists and pays out webbing, capping chest load — the belt deliberately gives way rather than breaking ribs. |
Other cars and driving objects
- Car tire Several different rubber compounds reinforced with steel and textile cord — closer to a composite than to rubber.
- Car battery Lead and lead dioxide plates in dilute sulfuric acid, in a polypropylene case — mostly lead, by weight.
- Airbag A coated nylon bag inflated by a small solid-propellant gas generator in about thirty milliseconds.
- Brake pad A friction compound of fibres, fillers and resin, moulded and bonded onto a steel backing plate.
- Windshield (windscreen) Two sheets of ordinary glass laminated to a tough plastic interlayer, which is what stops it falling out.
- Spark plug A ceramic insulator carrying a centre electrode of nickel, platinum or iridium inside a steel shell.
Common questions
- What is a Seatbelt made of?
- Woven polyester webbing designed to stretch a controlled amount, plus a locking retractor and a pyrotechnic pretensioner.
- What is the webbing of a Seatbelt made of?
- Woven polyester yarn, about 46-48 mm wide. Polyester holds its strength when wet and resists ultraviolet far better than the nylon that was originally used.
- What is the designed stretch of a Seatbelt made of?
- Weave geometry that allows a few per cent elongation under load. A completely inextensible belt would transfer the whole deceleration to the ribcage; controlled stretch spreads the load over more milliseconds.
Related pages
- Car tire Several different rubber compounds reinforced with steel and textile cord — closer to a composite than to rubber.
- Car battery Lead and lead dioxide plates in dilute sulfuric acid, in a polypropylene case — mostly lead, by weight.
- Airbag A coated nylon bag inflated by a small solid-propellant gas generator in about thirty milliseconds.
- Brake pad A friction compound of fibres, fillers and resin, moulded and bonded onto a steel backing plate.
- Windshield (windscreen) Two sheets of ordinary glass laminated to a tough plastic interlayer, which is what stops it falling out.
- Spark plug A ceramic insulator carrying a centre electrode of nickel, platinum or iridium inside a steel shell.
- Pencil Stationery and paper
- Tennis ball Sport and games
- Banknote Around the house
- Golf ball Sport and games
- Paper Stationery and paper
- Glass Building materials
Sources
- Typical range compiled from manufacturer specifications — At One Place