Four-Ball Machine Friction Unit Geometrical Parameters

Standard studies of the lubricants tribological properties are carried out on a four-ball friction machine. The friction unit of such machine is the same diameter contacting steel ball pyramid. To provide normal operation of this unit, it is necessary to ensure the upper pyramid ball stable sliding over the three lower fixed ball bearings. Other friction unit balls movements and displacements are unacceptable. Creating a calculation model friction unit makes it possible to determine such conditions. These model static equilibrium equations are the basis of the friction unit balls. Recording equilibrium equations with subsequent solution allows to perform analysis of the friction unit parts geometrical parameters effect onto stable operating conditions and to determine the optimum values of these parameters. The results can be used to create new laboratory facilities for the of the lubricants tribological properties study and to improve this four-ball machine.