The seat belt’s automatic locking mechanism is designed to secure a child safety seat. This feature typically engages when the belt is fully extended and then retracted. Once engaged, the belt can only tighten further until the mechanism is disengaged. For instance, pulling the shoulder belt all the way out will often activate this lock, preventing further loosening as it retracts.
This automatic locking function enhances safety, especially when securing car seats. By ensuring a snug fit for the child seat, it minimizes movement during a collision, thereby reducing the risk of injury. Historically, this feature has evolved from simple lap belts to more sophisticated systems that provide greater occupant protection in vehicles.