What is the function of an ALR seat belt retractor?

The function of an Automatic Locking Retractor (ALR) seat belt retractor is to lock the belt when it is pulled out more than a specific length, typically between 12 to 18 inches. This feature is designed to secure a child safety seat in place once the seat belt is fully extended and then retracted slightly. By locking the belt, it prevents any further extension and ensures the seat is snug against the vehicle seat, minimizing the movement of the child safety seat during a crash. This locking mechanism is crucial as it enhances the safety of child passengers by ensuring that their restraints are effectively securing them within the seat, thereby reducing the risk of injury in the event of a collision.

The other choices do not reflect the functioning of an ALR retractor accurately; for example, a seat belt that always remains loose does not offer the necessary protection. Similarly, locking only in high-speed impacts does not address the restraining needs in lower-speed situations, and locking when less than 12 inches pulled would not provide adequate security for child restraints. Hence, understanding the correct operation of ALR retractors is key to ensuring the safety of children in vehicles.