A seat assembly for an occupant of a vehicle possibly subjected to upsetting forces generally consisting of a base member mountable on a body portion of the vehicle, an occupant seat means for restraining an occupant positioned on the seat, means operatively interconnecting the base member and the seat for guiding the seat along a line of travel when the seat is displaced relative to the base member, means operatively interconnecting the base member and the seat for dampening a force imposed on the seat in first direction along the line of travel and means operatively interconnecting the base member and the seat for dampening a force imposed on the seat in a second direction along the line of travel.