What must be secured first when connecting boom sections?

When connecting boom sections, securing the bottom pins first is crucial for ensuring stability and alignment during the assembly process. The bottom pins provide a foundational connection that holds the weight of the sections and maintains the correct positioning. This initial stabilization is vital before any additional components, such as side plates or top pins, are attached.

Securing the span wire prior to connecting the boom sections, for instance, would not provide the necessary structural support that the bottom pins offer, as the boom sections might shift or become misaligned, making the assembly process more challenging. Moreover, the side plates are typically used to reinforce and support the connection but are not responsible for the foundational stability needed at the outset. The top pins, while important for completing the connection, should be secured last after the bottom pins and other elements have been correctly positioned and secured. By starting with the bottom pins, workers ensure that the entire assembly is safe and properly aligned from the beginning.