What are the principal parts of Category 1 and Category 4 cranes?

The principal parts of Category 1 and Category 4 cranes include components essential for their operation and structural integrity. The correct answer identifies key elements such as the boom, which is the extending arm that supports the load, and the machinery house, which houses the crane's operational mechanisms. The rotate bearing allows for the rotation of the crane's upper structure over the supporting base, ensuring smooth movement during operation. The supporting structure provides the necessary base and stability for the crane, while the travel system facilitates the crane's movement across various job sites or locations.

These components are crucial for the crane to function safely and effectively in lifting and moving materials, making them foundational to understanding crane design and safety protocols. Each component plays a distinct role in the crane's operation, contributing to the overall safety and efficiency of its use in construction and other applications.