Hinge for a vehicle seat

The adjustment unit (205) fitted to a vehicle seat, to adjust the pitch of the backrest, gives a relative movement between the upper (211) and lower (209) sections of the seat to give a free central swing movement to the backrest through a swing section (214). A locking pawl (232) is at the swing section, to engage a locking unit (235) at the lower seat section, to lock the backrest in the required angular setting. A barrier (260) with a retaining cam (264) prevents the pawl from opening away from the locking unit.