Gravity locking articulation for a briefcase

A gravity locking articulation for a briefcase comprises a first and second cam plates disposed between hingedly connected ends of support links of the briefcase, and a sphere rollingly disposed within a generally annular race defined between the cam plates. The cam plates are fixed to respective links so as to rotate in opposite directions during opening of the briefcase. When the briefcase is in a vertical position the sphere is intromitted into a receiving pocket defined by spaces in the respective cam plates when the spaces are brought into registry. Stop surfaces in the respective cam plates to either side of the receiving pocket come into abutment with the sphere to stop further outward rotation of the links, with the frame members of the briefcase being spread only partially. Inward closure of the frame members is unimpeded.