Couplings Clutches Spur gears Bar drives Cam drives Belt drives Two parallel shafts Two coaxial shafts Rotation limitation Car differentials Variators Gear shifting Bevel gears Epicyclic drives Worm gears Pin gears Face gears Archimedean spiral gears Friction drives Chain drives Processing metal and wood Object position control Folding and stretching Direction during motion Toggle linkages Snap motions Creating vibration Safety clutches Manipulation and orientation Indexing and positioning Measurement and control Mechanisms for copying Opening closing entrances Mixing machines Pumps and engines Hydraulic and pneumatic