A [b]four-bar mechanism[/b] is a mechanism having [b]four rigid links[/b].[br][list][*]The fixed link is called the [b]frame[/b].[br][/*][*]There is one rotating link called the [b]driver[/b] or [b]crank[/b].[br][/*][*]The other rotating link called the [b]follower[/b] or [b]rocker[/b].[br][/*][*]The fourth is a floating link that does not rotate about a fixed center and is called a [b]connecting rod[/b] or [b]coupler[/b].[br][/*][/list]Drag the point at the end of the crank to operate the mechanism.