Four-Bar Linkage

A four-bar linkage is a mechanical system composed of four interconnected rigid pieces, or bars, arranged in a loop. One bar acts as a fixed frame, while the others move relative to it. When one bar (the input link) is moved, it causes the connected bars to pivot and produce a specific motion at the output link. This setup is used to transfer, amplify, or transform motion in machines such as engines, robotic arms, and suspension systems. The four-bar linkage is valued for its simplicity, versatility, and ability to generate a variety of controlled movement patterns.