An interesting topic of this chapter is that of fourbars. These mechanisms can be seen in such real-world examples as locking pliers, bicycles, pistons, and oil well pumps. Fourbar mechanisms have three different inversions, meaning that there are three possible links that could be converted into the ground. This produces three other fourbars with unique motion. These are the crank and lever mechanism, double crank mechanism, and the double lever mechanism. Crank and Lever This inversion uses a crank attached to a coupler to drive a lever - as seen in oil well pumps. The lever is able to oscillate about a fixed point in its center where it is attached to ground. Due to the rotation of the crank, a piston or other attachment is able to produce a repeating motion. Double Crank This mechanism has two cranks that are connected by a coupler. This mechanism powers locomotive wheels. The cranks rotate, which rotates the wheels of the locomotive. Double Lever The double-lever mecha...