How does a compound bow work?

A compound bow is based on a pulley and lever system; as the string is drawn back, the pulleys rotate until the pulley radius is doubled at full draw. Today's compound bows are more efficient and return a higher level of energy than they take to draw.

The compound bow was first introduced in 1966, and its increasing popularity in the United States has made it the predominant bow choice for archers. The pulley/cam system makes for stiffer limbs than a recurve or long bow, providing more energy and better accuracy while being less temperamental to changes in temperature and humidity.