What term describes a grooved pulley-wheel used to change the direction of a rope's pull?

The term that describes a grooved pulley-wheel used to change the direction of a rope's pull is "sheave." A sheave is specifically designed with a groove around its circumference to help guide and support the rope or cable, allowing for smoother movement and reduced friction. This design is essential in rigging systems, as it enhances the efficiency of lifting and pulling operations. The use of sheaves is fundamental in applications where the direction of the load needs to be redirected, such as in cranes or other lifting devices.

Other terms listed may refer to similar components but do not have the precise definition associated with a sheave. For instance, a reel typically refers to a cylindrical device that winds or unwinds a cable or rope rather than changing its direction. A pulley block consists of one or more sheaves and may refer to a complete assembly that includes the sheaves and other components. A guide wheel may not specifically pertain to rigging terminology in the same way that sheave does, as it can refer to various applications outside of this context. Understanding these distinctions reinforces the importance of terminology in rigging operations.