Britax

Technology Update: Anti-Rebound Bar

Rebound is a force that doesn’t receive much attention as a subtopic of child passenger safety. As technicians, we know that every force has an equal and opposite reaction. Rebound, in the context of vehicle safety, is the equal and opposite reaction to an initial frontal impact experienced in a vehicle crash. The CPS curriculum defines it as the “reactive motion in the opposite direction after initial impact has occurred.”

To better understand the benefits of a rebound-limiting device, think about the events of a typical frontal and rear impact crash without a rebound-limiting device.
In a frontal collision, a CR continues to move forward, using the stretching of the belt webbing, and down through the compression of the vehicle seat cushion. After the initial impact, the CR “wants” to move back to its original state, but due to the elongation and compression previously mentioned, the CR dramatically overshoots its original position and comes into contact with the vehicle seat back. As a result, the child’s head often comes into contact with vehicle seat or other parts of the vehicle, such as the “C” pillar, mirrors or video screens.

With a rear-facing convertible CR, several manufacturers manage rebound energy via the use of a rear-facing tether. This tether limits the amount of travel the seat is allowed to make once past its original position. In the infant carrier category rebound is being (and has been) addressed with a feature appropriately named an Anti-rebound bar. This component is affixed to the in-car base of the infant carrier and limits the movement described above by forming a rigid “L” shape with the base bottom pressed against the bottom and back seat cushions of the vehicle. The reduction in child restraint movement then allows the harness in the restraint to perform its designed function and also keeps the child’s head from contacting the back of the vehicle seat and/or other items previously mentioned.

In a rear impact collision, the CR will attempt to rotate toward the rear of the vehicle, which is towards the point of impact. The same impact risks occur as described in a frontal rebound. The rebound of a rear crash event will cause the seat to move back to its original position similar to the initial impact of a frontal crash.

In the case of a rear impact the CR will attempt to rotate toward the rear of the vehicle towards the point of impact, but the rear facing tether (in a convertible CR) or the anti-rebound bar (in an infant carrier) will significantly reduce the distance it will be able to rotate toward the vehicle seat back during the crash event. Again, this reduction in motion allows the harness in the restraint to perform its designed function, while keeping the child’s head from contacting the back of the vehicle seat.

On infant carriers, an anti-rebound bar has been used on the Britax Companion® Infant Carrier and is currently used on the Britax Chaperone® Infant Carrier, Safe-n-Sound™ Unity Infant Carrier in Australia and the Britax Baby Safe in Europe (all companies are part of the Britax Childcare Group, Ltd).

The Chaperone infant carrier and stroller come in four fashions. The Chaperone infant carrier (SRP: $229.99) will be available in independent and mass retailers in June 2009; the stroller (SRP: $299.99) starting in August 2009. A single adapter strap will be available to allow the Chaperone stroller to be used with other major manufacturer’s infant carriers. The strap will also allow the Chaperone infant carrier to be used in other major manufacturer’s strollers.

Submitted by: Sarah Tilton, CPS Advocate, Britax Child Safety (Charlotte, N.C.)