Mechanisms

Gears- A toothed machine part, such as a wheel or cylinder that meshes with another toothed part to transmit motion or to change speed or direction.

Pulley- a wheel with a grooved rim in which a rope, chain, or belt can run in order to change the direction or point of application of a force applied to the rope, etc.

Hinge- A jointed or flexible device that allows the turning or pivoting of a part, such as a door or lid, on a stationary frame.