What is the primary purpose of a rooster sheave or auxiliary boom point sheave?

The primary purpose of a rooster sheave or auxiliary boom point sheave is to separate the hoist lines. This component plays a crucial role in the rigging and lifting operations of a crane by providing a dedicated point for the hoist lines to run. By doing so, it helps to distribute the load more evenly and prevents line entanglement, allowing for safer and more efficient lifting operations.

Separating the hoist lines can also aid in reducing wear on the lines themselves, as they can operate more freely without the risk of crossing over one another. This separation is essential in complex lifting scenarios where multiple lines may be in use, such as in tandem lifts or when using various attachments.

The other provided options focus on aspects like load capacity, crane speed, and maintenance needs, which are not directly influenced by the function of the rooster sheave. Instead, the main function that enhances operational safety and efficiency lies in the separation of the hoist lines, making option B the key feature that defines the purpose of a rooster sheave.