What should you lock when performing work on counterweights or during boom assembly?

When performing work on counterweights or during boom assembly, it is crucial to lock the swing. Locking the swing serves as a safety precaution to prevent unintended movement of the boom. This action ensures that the boom remains stable and will not swing unintentionally, which could lead to accidents or injuries during the assembly or maintenance process.

Safety precautions are vital in rigging and crane operations, as they help protect workers and equipment. By locking the swing, you create a secure work environment, reducing the risk of the boom swinging and potentially striking workers or causing equipment to be mishandled.

Other components, such as control levers or output systems, may also require attention during crane operations, but they do not specifically address safety concerns related to the stability of the boom while working on counterweights or assembly, making locking the swing the most relevant and necessary action in this context.