Which of the following describes a sheave's function?

A sheave, often referred to as a pulley, primarily serves to change the direction of a rope or cable. When a rope passes over a sheave, it effectively allows the operator to pull or lift the load in a different direction than that of the applied force. This function is pivotal in rigging applications, where it enables more efficient movement of materials and helps in managing loads, particularly in applications where space or direct lifting isn't feasible.

In contrast, securing the load is a separate responsibility associated with load rigging equipment and practices, rather than the sheave itself. Providing stability to the crane typically involves design features and balancing methods, not a function of the sheave. Enhancing lifting capabilities can be influenced by the use of sheaves in a system, but this is a broader application of mechanical advantage and not the primary function of the sheave itself. Therefore, the primary role of a sheave is indeed to facilitate the changing of a rope's direction.