This apparatus locks a tilt adjustable or reversible back rest (2) of a car seat (1). It has a back rest pivot point (4) and an absorbing plate piece (3). There is also a barrier section (14) that is a motion actuator (10). The actuator is at least associated with a peripheral actuator (15). The profile of the car seat has a rest position given when no-one is sat in the seat and the profile of the seat is adjustable. The peripheral actuator is made so that it delivers the greatest control power to the actuator.
