Athenian cultural dominance continued throughout the Roman period, and the buildings added to the Agora reflect the educational role of the city, a role that ended only with the closing of the pagan philosophical schools by the Christian emperor Justinian in A.D. 529.
Bearing, in machine construction, a connector (usually a support) that permits the connected members to rotate or to move in a straight line relative to one another. Often one of the members is fixed, and the bearing acts as a support for the moving member. Most bearings support rotating shafts against either transverse (radial) or thrust (axial) loads.
In the roller bearing, the roller is a cylinder, so the contact between the inner. and outer race is not a point but a line. Th is spreads. the load out over a larger area, allowing the bearing to. handle much greater radial loads than a ball bearing. However, this type of bearing is not designed to handle.