Lock-off is a built-in mechanism in a child restraint system (CRS) that functions the same way as a locking clip – to lock the seat belt in a fixed length so that it is always at a proper installed position during a crash. If a CRS is not installed properly and locked, it can loosen over time and this will pose a threat to how the mechanism works during a crash.
As easy as it may seem, we always find parents used them incorrectly in each check events we conducted. The most common error is not using them at all. Their CRS is simply belted in and not even in a firm installation.
Second most common error is having the seat belt going through the lock-off but only half-way in as per in the picture below.
What is dangerous about this, is the seat belt will be pinched at where the lock-off ends, damaging and weakening the webbing of the seat belt. Vehicle owners may need to replace their seat belt system once the seat belt is damaged. It is a very expensive error for such a simple thing.
On one occasion, we witnessed how the caregivers doesn’t know what to do with the excess belt that has an emergency locking retractor (ELR). The seat belt were pulled out to the maximum and the excess seat belt are routed in a loop through the lock-off (refer picture). This is wrong!
The correct way is to make sure you follow the instructions by the manufacturer. Sometimes lock-offs are made for one orientation of installation. In a CRS, there can be two sets of lock-offs, each for rear-facing and forward-facing. Whatever the system of the lock-off is used, the whole seat belt width should go through completely along the teeth of the lock-off like in the picture below.
Check your CRS installation today to ensure that the lock-off is used correctly!