What is a small grooved wheel that changes the direction of the halyard pull called?

The term that accurately describes a small grooved wheel that changes the direction of the halyard pull is known as a sheave. A sheave is integral to pulley systems, where it allows for the efficient transmission of force, enabling the operator to lift or adjust loads with greater ease. The grooved design of the sheave helps to guide the rope or line, ensuring that it remains in place and functions effectively without slipping off.

While a pulley can refer to the entire assembly, including the frame and other components, a sheave specifically denotes the wheel itself. Understanding this distinction is crucial in various applications, particularly in firefighting, where equipment relies on these mechanisms for tasks such as raising ladders or hoisting materials to elevated positions. Knowing the correct terminology helps ensure effective communication in the field and, ultimately, enhances operational safety.