Seat belts tighten using a piston mechanism that is activated during sudden deceleration or impact.
The referenced video provides a glimpse of this process, describing that a piston is pushed in response to a sudden event, resulting in the seat belt tightening. More specifically:
- Sudden deceleration: During a collision or sudden braking, the car experiences rapid deceleration.
- Piston activation: This deceleration triggers a mechanism that pushes a piston. This mechanism is related to the inertia reel within the seatbelt assembly.
- Seat belt tightening: The movement of the piston causes the seat belt to tighten, restraining the occupant and preventing them from moving forward excessively.
- Preparation for impact: The tightening action occurs almost instantaneously, preparing the occupant for the impact and reducing the risk of injury.
The critical point is that this tightening mechanism is designed to react before the occupant hits any part of the vehicle's interior. This increased time allows other safety features, such as airbags, to deploy and function effectively, further minimizing potential injuries. Modern seatbelts often incorporate pretensioners, which use various methods, including small pyrotechnic charges or electric motors, to quickly retract any slack in the belt during a crash.
