When an accident occurs, it is critical that passenger is securely retrained by the seatbelt so as to protect the passenger from its forward motion to hit the windscreen. In some severe instances, reaction delay and slacks in the webbing would still cause passenger to move underneath the seatbelt causing physical damage to the lower limbs. Modern seatbelt systems are now fitted with a pretensioning function to allow the removal of belt slack in splits seconds after the crash event.The mechanism to reduce webbing slack is through the seatbelt pretensioner when actuated will pull tight the seatbelt webbing. There are two ways to achieve this depending on the type of seatbelt system used：
- Retractor Pretensioning system
- Buckle/Lap Pretensioning system
In the retractor pretension system, slack removal is controlled by movement of a cogwheel. During an onset of a crash, sensors transmit signal to the pretensioner causing ignition of the pyrotechnical squib within a tubular construct containing a number of metal balls (ball in tube). An outward pressure within the tube expels the metal balls into cogwheel and forces it into rotating motion. This motion in turn moves the spindle in a rotation to retract and thus retract the seatbelt webbing.
In the Buckle/Lap pretension system the mechanism is the same except that the pyrotechnical device expels a piston device within a tube which in turn pulls a cable connected to the seatbelt buckle/anchor which would move farther away from the passenger, thereby removing any webbing slack that exists.
Iron Force has over 20years of experience working with first class safety system manufacturers to develop the latest seatbelt technologies that propel the vehicle seatbelt. To date, we have been shipping over tens of millions components that are now used in the everyday vehicle we see today.
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