Motor vehicle seat part comprising an anti-submarining crosspiece

A seat pan of an automobile vehicle seat and comprising:

• an anti-sub-marining cross member to limit the movement of a pelvis of a user towards the front of the seat, the cross member extending crosswise to a seat pan framework and being able to move towards the front while exerting pelvis retention forces during the movement of said pelvis and cross member towards the front of the seat;
• a seat pan including energy dissipation means to control, from a predetermined threshold, said forces transmitted by the cross member to the occupant of the seat,
• the ends of the cross member being connected to upper ends of links, the links pivoting on the seat pan framework about an axis stationarily fixed to the framework and passing through lower ends of said links,
• wherein the movement of said cross member towards the front is in the form of an arc of a circle centered on the fixed axis, defined by the pivoting of the links towards the front, opposing the retention force exerted by the energy dissipation means which are connected to upper ends of the links and near the cross member.