Chest clip or also known as ‘retainer clip’ is a two-part clip that is used to buckle the two harness straps together so it stays on the shoulder and chest of a child during a journey. It can be found on an FMVSS approved safety seat (child restraint system, CRS).
Most children at a certain level of development will want to ‘escape’ from being retained in a harness by taking out their arms. This poses a serious risk of injury to the child during a crash as all the forces will be focusing on the crotch buckle and the child abdomen instead of being spread throughout the shoulder and chest area where the harness should be.
A chest clip will prevent this from happening if used CORRECTLY.
However, you may not find a retainer clip on your car seat if they’re UNECE approved as there is a specification stated clearly under R44.04 that a single operation is required to release the child from the restraint. By having a retainer clip, it is already considered as ‘two operations’ to release the child. This lengthen process will slow down the rescue operation.
Apart from making sure that the position of the shoulder harnesses are always at the correct location before a crash, the retainer clip also functions as an energy management device. During a frontal crash, the retainer clip will move from its original location at the chest, downwards. This process slows down the frontal jerking of the child’s abdomen effectively reducing neck loads and injuries.
On the other hand, the energy management function of a retainer clip in a UNECE CRS is taken over by the harness pads. Because of this, you will see the harness pads for UNECE CRS is much bigger and thicker than the pads found on FMVSS CRS. The bigger size and thicker design will absorb some of the impact energy during a crash. Some harness pads have anti-skid layer underneath to ensure the harnesses stay on the child’s shoulder at its correct position at all times.
So, can you add a retainer clip to a CRS that is not designed with it?
The answer is no, because it is not crash tested along with it and any modification done to a CRS will void its warranty.