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.
A greased roller bearing in an electric motor is offered to demonstrate the possible grease service life. In general, the suspension of rotors with grease-lubricated roller bearings is a widely used and well-known application, and is a good example for a bearing subjected to various influencing factors.n practice, only a few grams of grease are used for lubricating rolling element bearings and this quantity typically lasts a long time. An exact calculation of the grease service life is consequently of particular importance.