What is the main structural member of a ladder that supports the rungs?

The main structural member of a ladder that supports the rungs is the side rails. These are the vertical components that run along the length of the ladder, providing stability and strength. They are designed to bear the weight of the user and the load they are carrying while ensuring that the ladder maintains its shape and integrity during use. The rungs are secured between the side rails, allowing for safe climbing and descent.

While decking and rung blocks serve specific functions within the ladder's design, they do not constitute the primary support structure. The beam often refers to a horizontal structural component, but in the context of ladders, side rails are the pivotal elements that maintain the ladder's overall support and dimensional integrity. Understanding this structure is crucial for safe operations and maintenance in firefighting and rescue scenarios.