This review highlights the major efforts devoted to development of molecular gears over past 40 years, from pioneering covalent bis-triptycyl systems undergoing intramolecular correlated rotation in solution, most recent examples gearing anchored on a surface, which allow intermolecular transmission mechanical power. Emphasis is laid different strategies devised progressively control architectu...

| Gear theory is reexamined and we nd optimal shapes for gears. As optimality criteria, we allow: (1) minimal frictional losses (highest eeciency) assuming linear law of friction or (2) uniform maximum stress (it will wear out slowly and last the longest) assuming Hertzian contacts or (3) uniform maximal temperature, assuming we are in a high power limit in which all heat is removed by the lubr...

In this study, an optimization methodology is presented to systematically define optimal tooth modifications introduced by head-cutter geometry and machine tool settings to simultaneously maximize the EHD load carrying capacity of the oil film and to minimize power losses in the oil film of facehobbed spiral bevel gears. The presented optimization procedure relies heavily on the EHD lubrication...