Pulleys make it easier to raise and lower heavy loads. We can find them all around us--on boats, bikes, flagpoles, and more! Pulleys are made up of an axle and a wheel with a groove around its edge. The grove keeps a rope, chain, or cable from slipping off the wheel. Pulleys come in a variety of sizes and materials and can either be fixed or moveable. When two or more pulleys work together, they're called compound pulleys. In this book, readers will learn about where pulleys can be found, see examples of how they are used, and learn about the pulley's inventor. Provided by publisher.

Includes index.

Learning about pulleys --Pulley parts -- Pulleys at work -- What's a fixed pulley? -- What's a movable pulley? -- What's a compound pulley? -- Archimedes's pulley -- Modern pulleys -- Pulleys in your home -- Bikes and gears.