How Does a Compound Bow Work?

What is a Compound Bow?

A compound bow is similar to a traditional longbow or recurve bow, except its design and material give it significant advantages, among them increased power and accuracy. Like all bows, compound bows store energy in their limbs, which are compressed as the string is drawn back. When the string is released, the limbs snap to their original shape, transferring the potential energy into acceleration of an arrow.

Features

The primary feature of a compound bow is the use of one or two pulleys to compress the limbs. Not only do the pulleys magnify the force applied to the string by the archer, they also provide an advantage known as "let off." A standard longbow requires nearly as much force to hold it fully drawn as it does to draw it back. In a compound bow, once the string is about 50-80% drawn, the pulleys reduce the amount of force required to continue drawing the string.

Design

The cables and pulleys make the compound easier for the archer to use, but the real secret to its power is in the composite materials from which it's constructed. The central part of the bow where the arrow is nocked is called the riser. It's usually made of a sturdy aluminum alloy.

Accessories

Archers using compound bows often use a variety of accessories. Unlike traditional bows, which are often fired bare-fingered, archers using a compound bow often use a release, a small mechanical pincer with a Velcro strap, which transfers the force of the draw to the wrist instead of the fingers.
source : eHow