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What are sheaves in a pulley system?

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A diagram displays six types of simple machines with labeled illustrations: inclined plane, wedge, screw, lever, wheel and axle, and pulley, each shown with real-world examples like ramps, axes, screws, seesaws, door handles, and pulleys lifting objects. — simple machine Six simple machines for transforming energy into work.

In the context of a pulley system, a sheave is defined as a wheel that features a grooved rim. These grooved wheels are designed to carry a flexible material—such as a rope, cord, cable, chain, or belt—within that groove.12

When used in a block and tackle arrangement, these sheaves are typically housed within a frame or block, allowing them to rotate independently to transmit energy and motion. By utilizing one or more of these rotating wheels, a system can achieve mechanical advantage, which is particularly useful for lifting heavy weights.12