The adjustment unit (105) fitted to a vehicle seat, to adjust the pitch of the backrest, gives a relative movement between the upper (111) and lower (109) sections of the seat to give a free central swing movement to the backrest through a swing section (1...

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 (2...