National Commission for the Certification of Crane Operators (NCCCO) Mobile Crane Practice Exam

The heel pins are not considered a part of the boom itself, as they are primarily structural elements used to connect and secure the boom to the crane's superstructure or base. The boom is the long extendable arm of the crane, and it typically includes components that directly contribute to its function in lifting and extending, such as sheaves, which guide the wire rope; the wire rope itself, which is integral for lifting loads; and the chain, used in some configurations for various lifting and movement tasks.

In contrast, the other components like sheaves, chain, and wire rope are directly involved in the operational function of the boom, assisting in load management and movement. Understanding the distinction between structural components and operational components is crucial for effective crane operation and safety.